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68ragtop
07-25-2016, 11:38 AM
I figured rather than continuing to derail the "favorite compound" thread I would start a new one.;)

As a few of you guys know I have been trying to fishing up the paint work on my decade long project "nemesis" 68 GTO. I have put a lot of effort in this car to make sure I miss nothing. Things have been going business as usual until now. first problem started benign enough where I wasn't able to cut out 2500 grit scratches as the clear is hard as a rock. So I got 3000 grit paper & I have had great success since then getting them out. However, now as I am polishing I have been noticing directional sanding lines in the clear. The don't stand out, but are detectible when I look at the right angle. These lines follow the direction I last sanded be it with 2500, or 3000. They are not lower level (courser grit) scratches. That was my first thought too, but If I re-sand in an opposite direction the marks will change directions. If I do ///\\\ I can see that too. Seems crazy, The only way I can make them less noticeable is to final sand in circles & I do Not want to do that. Goes against everything I know about keeping things straight. However, when I did try circles it removes the lines for the most part, but what it solves in lines, it creates in all kinds of micro anomalies in the refection. Not sure what is worse to look at. I also did try 3000G trizact & the disks are too soft, they will mimic the underlying sratch marks.

So, I went this morning & looked very close at the last car I painted. That car was color sanded 1 week after being sprayed with 1500 orbital & polished. The car looks great & it's straight, but when I got down on the the surface at the same angle I saw the exact same unevenness I am dealing with now. No directional lines because of my orbital sanding method, but rather just general "micro ripples" randomly in the reflection. I worked on that car for nearly 2 years & never noticed before.

I am starting to believe that what I am looking at could & most likely is in all paint work at some level. Have just raised my expectation on this car to a level not even possible?

Heres the angle I am looking at

68ragtop
07-25-2016, 12:08 PM
Here's a couple picts to give you a better idea of what I am looking at.

In the overall picture the door looks very straight & I have no complaints with this.
And yes, the big wave in the lower front part of the door is a GTO body line :D

68ragtop
07-25-2016, 12:12 PM
here is a close up of the same door at a sharp angle. Pretty obvious in the light tubes.

EDIT: for some reason the images are not loading in very high resolution. Sorry, not sure why they are pretty small files. Anyway, you can still see what I am talking about if you look at the center light tube.

I'll see if I can figure out how to post them in a bigger format.

68ragtop
07-25-2016, 12:43 PM
Here are better images. I loaded them on the server at work.

Looks straight & it is, but look really close at the fluorescent tubes on the close up with a tighter angle. then you can see the deviations.

What seems to work best so far is final sanding like this. \\\\\\ ////// l l l l l l this process still leaves ripples I can see but directional lines that really catch the eye are replaced with random unevenness. Neither way really looks good IMO. But might be the best it can get?


http://automationsystems.us/images/GTO/right-door.JPG


http://automationsystems.us/images/GTO/zoom-door.PNG

68ragtop
07-25-2016, 03:09 PM
Here a fender, sanded put not polished. same thing.

http://automationsystems.us/images/GTO/left-fender.JPG

Bob K
07-25-2016, 03:39 PM
Consider that it is not the grit that is causing the problems. Look elsewhere and rule out other defects. For instance are you using adhesive backed paper on a hard rubber block. Maybe there are lumps of old adhesive on the block that cause parts of the paper to dig in. Now I'm not suggesting that this particular problem exists but trying to show that things that you don't think of can be a problem and you may not look for them if you decide the problem is "A" but in realty it's "B". One other thing that comes to mind. Are you using to small of a block? Or the other end of the spectrum are you using to long of a block and digging in where you apply pressure with your hands and letting the center of the block float over the surface without cutting? Just things outside of grit size to think about. Since I'm not there to see it I can't come up with a definitive answer and to be sure maybe I wouldn't be able to even see the problem if I were there.

Bob K

68ragtop
07-25-2016, 07:10 PM
Hi Bob, My primary block is a narrowed (half width) 6" & 4" long durablock. Also I use a semi flexible 4" soft block from time to time for uneven surfaces. I even tried a .060" piece of aluminum. Same result regardless, might be a little worse with the soft block. I do appreciate you giving some thought to this. It's why I made the topic, hoping to see if anyone else has ideas, of maybe can confirm that this is just. for sure a good idea to rule out the simple stuff so we are on the same page.

One thing that is different from all the other cars I have done, is I recently added a bunch of wall lights. Its almost a ridiculous amount. I am realizing that this is why these marks are more visible. I have a 4' light fixture every few feet all the way around the shop. I took another picture with just the ceiling lights on & turned off the wall lights & I can't see the marks.

But, I know they are still there........ :D So am I looking to close?

Here's a picture with the lights off all the edges of the lights look clean & sharp. must be something to the way light grabs the sand marks & magnifies it? I am at a loss otherwise.

http://automationsystems.us/images/GTO/lights-off.JPG

Bob K
07-25-2016, 09:27 PM
Hope you aren't seeing sand marks below the surfacer that become visible when the surfacer shrinks. You seem to rule that out by seeing different directions in the scratches but if that was me looking at it I would doubt my memory when remembering which way they were oriented the time before.

I just had a memory laps a few minutes ago. I put 30 ounces of clear in the gun hanging on a wall rack. I had the empty cup in one hand and the strainer in the other. I set the strainer down and placed the lid on the paint gun. I left it loose because I didn't want to put a lot of strain on the rack when pushing the gun lid on with one hand. After all I was only going to walk 10 feet to my mixing table and put the stuff down and come back and use both hands putting the lid in place. Sure enough when I got to the mixing table I saw something that needed to be dealt with and one thing leads to another. So in two minutes when I went to spray the clear I had forgotten to finish putting the lid on the gun. At least it spilled on the floor and not on the car. Memory, a terrible thing to loose.

By the way' nice looking job. I might be tempted to let it be and see what it looks like in daylight in a week or so.

Bob K

68ragtop
07-25-2016, 10:05 PM
Hope you aren't seeing sand marks below the surfacer that become visible when the surfacer shrinks. You seem to rule that out by seeing different directions in the scratches but if that was me looking at it I would doubt my memory when remembering which way they were oriented the time before.

I just had a memory laps a few minutes ago. I put 30 ounces of clear in the gun hanging on a wall rack. I had the empty cup in one hand and the strainer in the other. I set the strainer down and placed the lid on the paint gun. I left it loose because I didn't want to put a lot of strain on the rack when pushing the gun lid on with one hand. After all I was only going to walk 10 feet to my mixing table and put the stuff down and come back and use both hands putting the lid in place. Sure enough when I got to the mixing table I saw something that needed to be dealt with and one thing leads to another. So in two minutes when I went to spray the clear I had forgotten to finish putting the lid on the gun. At least it spilled on the floor and not on the car. Memory, a terrible thing to loose.

By the way' nice looking job. I might be tempted to let it be and see what it looks like in daylight in a week or so.

Bob K

Thats a bummer on your paint incident, I started reading & I though you were going to tell me the gun was left over night with hardened clear in it. If it makes you feel any better I did the same thing a while back. Metal cup with the press in plastic lid. no idea why I didn't snap it in but a fresh pint of clear splashed all over when I swung the gun. Didn't loose all of it, but I had to stop & clean the gun enough so I could still use it. what a super sticky mess. At least it was clear. stickier, but cheaper. So I completely know the feeling.

This paint was sprayed back in May so its almost done shrinking. I did take some panels outside & they look unremarkable outside. no issues can be seen at all. its only in my shop that I can see them & Its not easy to spot them. Just surprised I can't get them out. I have always thought clear could be made perfectly flat, truly like glass, but either it can't be that crazy perfect, or I lack the talent. Funny comment on the sanding direction. I have a piece of masking tape on the top with notes, or I would forget too.... :)

Bob K
07-26-2016, 02:38 AM
I now you don't want to do it but I think if you go with a Trizact Clear Coat Sanding Disc on a short throw sander it may help. It's 1500 grit then go to 3000 Trizact before you polish. That may leave scratches too but they are random and not lined up parallel to each other. They may be harder to see. That's my process but I don't do show car work. You could try it out on a panel that you flattened by block sanding with 1000 wetordry. I know the sander doesn't level the paint as good as blocking but I don't think it will mess up a panel that was already blocked flat. Just do it to hide the scratches. Try it out on a test panel instead of your car. The Clear Coat Sanding Discs are on a hard backing, not soft like finish film or the other Trizact grits that are on a foam type disc. Use them wet. They have an amazingly long life span.

Bob K

68ragtop
07-26-2016, 06:19 AM
boy, we are for sure on the same page..... ;)

That's actually what I started with a few weeks ago & your exactly right. I would cut/polish & realized I wasn't getting the 1500 scratches out with the 3000 pads . I could see the orbital marks looking directly down on the panel. I don't recall how it looked on an angle as I could see bigger issues with the orbital scratch lines. Then I went to 2500 on paper & then I could just see those hand sanded lines. At 3000 paper they were gone looking directly at the panel & I was happy, for a bit until I saw those directional 3000 grit waves making just enough of a surface deviation to catch the light. thats what your seeing in the pictures above. I am calling them scratches, but no scratch is visible, just the way the light reflects at those tough angles.

I also tried 3000 trizact over the 3000 hand scratches & amazingly the disks are too soft to take the line/waves off, it just mimics them.

I'll bet if I had fresh/soft clear this step might work perfectly. It seems like I have to pick my poison at this point. Should never have let the clear get this hard, but I know a lot of guys do it. I was hoping for less defects with everything tight.

just for the record, I have been doing most of my testing on a test panels that I painted a couple weeks before I painted the car. I was trying to get the color right before painting. so happy to have those sacrificial panels. If I have to re-clear to work it when its soft, I can do that, But I just went through a ton of effort to paint everything in pieces to eliminate all tape lines. I really don't want to re-spray the body for sure, that would be a lot of extra work with all the jambs. haven't touched a piece of sand paper to that yet & won't until I have the best method underway.

If there was a 3000G stickit disk, maybe a quick pass with that would be just enough to knock those marks flat without making the deviations that come with orbital sanding? I don't think there is such a paper though?

I'm so close... :D

68ragtop
07-29-2016, 12:02 PM
Just an update. I got some 3000 grit meguiers paper. For sure a better quality paper than what I have been using. I did some sanding also trying a semi flexible plexyglass block I made. Really no difference & that thing is about as flat, as flat can be. One thing I am realizing is that where its noticeable is on the surface areas where the panels are shaped inwards. This no doubt this magnifies anything seen in light. Kinda the same way an outward curved panel "can hide an elephant" :)

I think I am coming to terms with this just being a urethane thing. my surface is as flat as I can figure out how to make it.

I also found the old "water bug" in a cabinet & cleaned it up. Seems to help get rid of the final directional marks & has a pretty stiff pad. It still works well, but I am not hooking to the hose. that was its Achilles heel I think.

Anybody else ever have one of these old school sanders? they were a pretty cool idea. I quit using it because somehow I would always end up with a piece of crap debris getting on the paper & making pigtails. I think it was because of the design of the water passing though all those crevasses under the pad. It actually works pretty well if I don't perforate the paper & just use a spray bottle. :) Is there a date code on this thing? I think it was purchased in the late 80's, possibly 90's

SamG
07-30-2016, 08:17 PM
Anybody else ever have one of these old school sanders?

I do! Drug it out a few months ago to do some sanding on a 57 Chevy. Finished it by hand but started with the waterbug. Mine has a thicker pad with a plate that punches holes in the paper. OR you could buy prepunched paper. I dug around a found a sleeve of prepunched 280 which was great for 'breaking' some pretty thick primer before finishing with 400/600.

I always thought I should have just bought 10 Harbor Freight jitterbugs and just used one until it quit then pulled another one out. Hard to beat a Hutchins orbital for longevity though.

SamG

Mike S
08-13-2016, 03:10 PM
From what I can see in some of the pictures, it looks like the infamous "urethane wave" or ripple.
I've studied this issue a lot and at car shows most of the cars have them and were mostly visible (if you know what to look for) on flat surfaces.
Some cars I have seen had extremely little to no wave and when speaking to those owners (who actually did the work themselves) they said how they block sanded the clear initially. Some started with 400 and others with 600 grit. I know, 400 sounds scary but I have tried that technique on my car using a hard block and it came out so good that I'll always use the 400 grit block sanding method as the initial cut before working my way up to P5000 then polish. You need a few extra coats of clear though being some will wind up on the floor. The last set of panels I did that way, I sprayed 5 wet coats of SPI clear on with a flash time of approximately 30-45 minutes between coats and got absolutely no solvent pop with that amount of clear. This was done with 10% (RTS) urethane retarder mixed with the clear to make it flow flat with v-e-r-y little peal so when sanding with P400 dry to level initially it went very fast before having a dull surface to work up the grit scale from with the remainder done wet. I start with P400 dry because it is so easy to see your work without having to dry a wet surface, then switch to P600, P800, P1500, P2000 wet on a Durablock pad. I only use the DA for the P3000 and P5000 pads that are slightly misted with a spray bottle the polish. I plan on showing my car so I don't mind going through the extra work to get a flat surface. Man, do I wish for the old lacquer days when we didn't have to worry about "wave" from these high solids clears.

Mike

Henry
08-13-2016, 09:41 PM
Man, do I wish for the old lacquer days when we didn't have to worry about "wave" from these high solids clears.

Mike

I do agree but lacquer did have its own problems and hard to paint when humid or raining. How do you spell "blush"?

Paint it, wet sand with 600, compound with the equivalent of Turtle Wax white polishing compound and be done. At least till it dulled if sanded and buffed too soon.

Henry

MARTINSR
08-14-2016, 10:14 AM
I do agree but lacquer did have its own problems and hard to paint when humid or raining. How do you spell "blush"?

Paint it, wet sand with 600, compound with the equivalent of Turtle Wax white polishing compound and be done. At least till it dulled if sanded and buffed too soon.

Henry

I can remember like it was yesterday the first time I used "Ultra fine" (rated at about 800) doing a lacquer job on a T bucket around 1979. It was like I had discovered a gold mine in 1849! HOLY CRAP that was like friggin magic paper!

Brian

68ragtop
08-14-2016, 06:02 PM
I have pretty much come to the conclusion that there are at some level "limitations" to how perfectly flat urethane can look. I sprayed a few test panels over the past couple weeks. I blocked with 400, 800, 1000, 2500, 3000, 5000 & polish. While the panel is no doubt flat, there are still these little tiny anomalies in the surface that can be seen at the right angle. Not wave, or flaws, or bad body work. Nothing that severe looking. Its almost similar to orange peel, but smaller, harder to see, but consistent once you know how to look for it. But it's still there with otherwise laser straight panels.

Today I went to to large car shows & every car I looked at I could find this "micro ripple" (I will call it). On some very high end cars it was a little hard to see, & on the other end of the scale many of them had the obvious urethane wave. most cars were somewhere in-between. It makes me feel better to know that its obviously just the way it is, but it kind of ruined how I look at cars now. I'm looking waaaay to close & not just looking at the car. A buddy of mine jacked me up today for showing him how to look for it. Now he said he sees it too & he said he doesn't want to look at cars like that. :D I did find a 3000 grit & 5000 grit wet paper I really like, but the 5000 does not last long at all. Many half sheets to do just one panel.

Also, am in love with mystic cut. Thanks for all the referrals on that product (in another thread). Easy to work with, cleans up easy & smells like bubble gum. 3M stuff will be working its way to the back of the cabinet. Also ordered a flex 3401 polisher, going to start with my rotary, then finishing with the 3401, then maybe mystic polish with the 3401 as well.

68ragtop
08-14-2016, 07:21 PM
I can remember like it was yesterday the first time I used "Ultra fine" (rated at about 800) doing a lacquer job on a T bucket around 1979. It was like I had discovered a gold mine in 1849! HOLY CRAP that was like friggin magic paper!

Brian

A friend of mine went to auto body school in the early 80's Shortly after he painted a 72 or 73 firebird formula in black lacquer. Was the shiniest thing I ever saw at the time. I have a picture of it somewhere is a scrap book..... I have never painted lacquer. Lots of single stage early on, no lacquer.

Henry
08-15-2016, 09:18 AM
A friend of mine went to auto body school in the early 80's Shortly after he painted a 72 or 73 firebird formula in black lacquer. Was the shiniest thing I ever saw at the time. I have a picture of it somewhere is a scrap book..... I have never painted lacquer. Lots of single stage early on, no lacquer.

Since being brought up a few days ago, I've been thinking a little on all the lacquer jobs I did way back when.

Gotta say, you sprayed over a wet sanded 400 scratch, wet sanded with 600 and compounded with white polishing compound on a wool pad.

If paint systems are so advanced today, how come we got away with wet sanding only to 600 and compound only with a wool pad and never see all the problems you are seeing today? We never saw the 600 scratch in the finish product.

We even did blends with it. You would fix your area then compound the surrounding area and spray lacquer over the repair and extend into your compounded area. Then sand and buff and done. Problem with that was after months of exposure you saw what looked like ringworm; a difference in color where you blended but not on all blends.

Most shops made the mistake with lacquer of painting in the morning and buffing in the afternoon. It was a "hurry up" the customer will be here at 5 to pick up the car. This resulted in the paint getting dull within a month as the thinner continued to evaporate through the top surface. On cars that mattered, we would not buff for at least 3 months and called that time to 'season' and we didn't get die back nearly as much.

We also would use lacquer as a guide coat. Spray some black lacquer on a fender you worked and block sand to get it perfectly level. SO, guide coat of today is nothing new.

Biggest problem with lacquer was its longevity and if not applied correctly it would crack and although you could clear it, your clear would lead to cracking. Oh, and the clear was not clear. DuPont clear was golden in color while RM clear was clear like water.

Listen, this art is full of variables. Lacquer is gone but the variable continue. Bottom line is it's a lot of work when you work this trade.

Henry

68ragtop
08-23-2016, 01:00 PM
I finally got to try out my new 3401 Flex polisher. Nice machine! pricey, but nice. Compact, lightweight & smooth, no vibrations. I like the fact that I can limit the speed on a dial, but yet the trigger is still variable. Similar to my Tig welder controls :D

Also still impressed with the Wizards Mystic Cut. Thanks again for that recommendation. Love the stuff. I have been cutting with yellow on my rotary, then switching to white on the Flex & finish with black. Honesty, I can't see any swirls in direct sunlight with only one compound. I will probably try another final polish as I am guessing that would still be "one better" than mystic cut, but I have to say its an awesome product.

68RT

68ragtop
08-26-2016, 07:33 PM
I just had a memory laps a few minutes ago. I put 30 ounces of clear in the gun hanging on a wall rack. I had the empty cup in one hand and the strainer in the other. I set the strainer down and placed the lid on the paint gun. I left it loose because I didn't want to put a lot of strain on the rack when pushing the gun lid on with one hand. After all I was only going to walk 10 feet to my mixing table and put the stuff down and come back and use both hands putting the lid in place. Sure enough when I got to the mixing table I saw something that needed to be dealt with and one thing leads to another. So in two minutes when I went to spray the clear I had forgotten to finish putting the lid on the gun. At least it spilled on the floor and not on the car. Memory, a terrible thing to loose.


Bob K

Was thinking of you & this post this afternoon Bob :(

Clearing a bumper cover & after the first coat I often will flip the gun upside-down, put my finger slightly over the fluid tip & fit the liner back to its origin size. I do this to see how much product I used. Simple trick & takes a few seconds.

Well, I must have pushed my luck & made a little too much pressure & blew the ring off while the liner & everything went to the floor with about 8oz of clear. Ruined my spray suit & left shoe. Took a while to clean up as well. As much as I like the PPS system, the main cup & ring are kinda cheap for what it costs. bad enough the liners are $1.80 each

Len
08-26-2016, 08:27 PM
Was thinking of you & this post this afternoon Bob :(

Clearing a bumper cover & after the first coat I often will flip the gun upside-down, put my finger slightly over the fluid tip & fit the liner back to its origin size. I do this to see how much product I used. Simple trick & takes a few seconds.

Well, I must have pushed my luck & made a little too much pressure & blew the ring off while the liner & everything went to the floor with about 8oz of clear. Ruined my spray suit & left shoe. Took a while to clean up as well. As much as I like the PPS system, the main cup & ring are kinda cheap for what it costs. bad enough the liners are $1.80 each

Check out the DeVilbiss DeKup system, I think it's designed better.

Bob K
08-26-2016, 10:22 PM
Sorry to hear that. As I get older I make more and more mistakes that don't seem like they would ever happen in a million years. Just be thankful that it was paint on the floor and not an unrecoverable catastrophe. I lightly touched the saw blade on my table saw a few weeks ago. It was running and I was on the back side where I shouldn't be and reached over the blade and the fingernail of one finger brushed the blade. Not a speck of damage but it put the fear of God in me. I use that saw a lot and am to comfortable so I do things I shouldn't. Well not any more, that's for sure.

Bob K

68ragtop
08-27-2016, 05:52 AM
I wasn't upset, I did it to myself. But I was surprised how easy the black lock ring came right off. If I would have just let gravity put the liner back to shape it would have been fine. Len mentioned the decups a while back. My LPS has the 3M on the shelf so I just grabbed those. I tend to fall to convenience at times.

I used to get upset as all heck when stuff like this would happen, but I have mellowed out a bit. trying to make & expecting everything to go perfect hadn't worked out over the past few decades so I finally conceded. Now I get disappointed more often than mad. ;)

does anyone else do that with their cup system? I typically only do it with clear, because I don't want to run out & have to mix more towards the end of the last coat, & I hate wasting expensive materials. I used to always just mix more than I need, but with the prices today I try to get a little closer.

surfin
08-27-2016, 11:45 AM
Urethane wave can be an issue when you lay it down to thickly or go for the home run. Longer flash times can help with that and if you subtly go less peel with every coat. Straight bodywork and flat primer helps as well. Hardblocking the clear helps too, but what's really important is what's happening as it does it's last flash. If you let it flash for 15 minutes and get some heat on it than you will have less wave.

bmarler
08-29-2016, 11:48 AM
I wasn't upset, I did it to myself. But I was surprised how easy the black lock ring came right off. If I would have just let gravity put the liner back to shape it would have been fine. Len mentioned the decups a while back. My LPS has the 3M on the shelf so I just grabbed those. I tend to fall to convenience at times.

I used to get upset as all heck when stuff like this would happen, but I have mellowed out a bit. trying to make & expecting everything to go perfect hadn't worked out over the past few decades so I finally conceded. Now I get disappointed more often than mad. ;)

does anyone else do that with their cup system? I typically only do it with clear, because I don't want to run out & have to mix more towards the end of the last coat, & I hate wasting expensive materials. I used to always just mix more than I need, but with the prices today I try to get a little closer.

i use the dekups system and do the same as you. put my finger over the nozzle and refill the liner. works great. then you can pop the cup off the adapter and either use a small funnel to add more paint, or take the liner top off and add. i absolutely love the system, its designed very well.

68ragtop
09-04-2016, 02:32 PM
Well, I did a little more experimenting with scrap panels. I am realizing now that 600 grit paper, even on a hard 1/8" thick aluminum sanding block, will still somehow mimic micro flaws in the clear & can't really get the surface ultra flat. I thought that a really hard block would compensate for the lack of lower cutting grits, but it really doesn't. I have a scrap door that I sprayed a few times now & have tried to block out some of these micro imperfections with 600, 1000, 2000, 3000, 5000 & polish. I used a machined piece of aluminum as my sanding block with the 600 & 1000. then went to a modified durablock. in the end, I still could see little micro ripples in the right light & reflections. Now, this being said these panels looked perfect & laser straight out of the shop. No urethane wave, nothing. But even then If I looked hard enough I could still see some micro ripple, but really, really hard to detect it.

So, I decided to spray a test panel & first sand in 400 dry using very light pressure with my aluminum block. then 600, etc, like I have been doing and so on to polish. This 400 step makes it much better, but now I can just barely make out the directional sanding marks from the 400. Just like our bodywork, once you hit a certain grit its ability to really cut is limited & things get mimicked.

I'll have to play around with a few different grits & see what works from here. The biggest problem I see is not having enough real estate to sand off that much clear. Seems like a crazy amount of sanding. I could care less on the test panels & haven't sanded through yet, but when sanding something that maters, sanding that much would make me really nervous.

might take 4 coats of clear to pull that off. I have never been a fan of putting on more than 2-3.

Bob K
09-04-2016, 03:07 PM
Just a thought here because I canít see what you are talking about but Iíll take a guess that maybe what you are seeing as ripples donít exist on the surface you are sanding. They may be ripples on the surface of the base coat and you are seeing them through the clear. If thatís the case no amount of sanding is going to remove them.

Bob K

Mike S
09-04-2016, 06:35 PM
I've had such good luck with spraying 5 wet coats of SPI clear on and after a week of curing, block it dry using a Durablock with P400 then P600-P800 and then continue blocking wet with grits up to P2500 before switching to Trizact 3000 & 5000 then polish. I could not be any happier with how mirror flat it is with no wave. At 5 coats (minimum 30 minutes flash time between coats so no solvent pop) you should have plenty of clear and be comfortable with starting with P400. I let the block glide over the clear and work it in a cross hatch pattern until it is just turn totally dull before moving up from 400.

Mike

68ragtop
09-05-2016, 09:13 AM
Just a thought here because I canít see what you are talking about but Iíll take a guess that maybe what you are seeing as ripples donít exist on the surface you are sanding. They may be ripples on the surface of the base coat and you are seeing them through the clear. If thatís the case no amount of sanding is going to remove them.

Bob K

Hi Bob, I was starting to think the same thing, but then I did some experimenting where I sprayed black sandable primer on a test panel. I blocked it with 400, then 600 & cleared it. It looked really flat while unsanded. Then I 8" blocked it starting with 600 & there was still some micro ripples after my final sanding & polish. I know we can talk about how the clear is sprayed causing it, but I cleared it with a sagola 4500 (very nice gun by the way) & it really layer down flat. IT could also be the PPG clear? I am sure some clears lay down better than others. But it seems like urethanes are just prone to not laying down like a puddle of water on a calm day. now that would be flat! :)

I don't think its anything I am doing wrong, I just way upped my observations. Since getting so dialed in to this urethane thing, I have gone to two car shows & have not found a car without it at some level. In fact most cars have it bad. Looked at some cars that had obvious urethane wave, to cars that had very, very little micro ripples. But all of them had something, at some level. it just depends on how close I wanted to look. The flattest car I found was a 62 impala. The owner was not around to ask what he did. But even so, its still had a tiny bit of ripple, but I had to look at it the same way I am looking at my panels right now.


Don't get me wrong, I am ok with how things look on the GTO, but I am recently fascinated with trying to get things to the edge of whats possible. Before all this research started I was at a high end indoor show where a guy had a car in black that was impossibly straight & flat. The car won a best paint award & it was just solid black! I just kept looking at the car & it has always been in the back of my mind wondering what was done to make that car stand out like that. Prior to painting my 68 GTO, I have never even taken a straight block to the clear. I wet sanded with flexible soft blocks until the late 90's then have been dry sanding with an orbital every since. In some ways I wish I would never have looked at things this close, its kinda ruined the way I look at & enjoy cars :( But, I have always tried to make things a little better as I get older. It sometimes prevents me from getting things done because I am too fussy. I am my own enemy when it comes to stuff like this. :( It's bittersweet.



I've had such good luck with spraying 5 wet coats of SPI clear on and after a week of curing, block it dry using a Durablock with P400 then P600-P800 and then continue blocking wet with grits up to P2500 before switching to Trizact 3000 & 5000 then polish. I could not be any happier with how mirror flat it is with no wave. At 5 coats (minimum 30 minutes flash time between coats so no solvent pop) you should have plenty of clear and be comfortable with starting with P400. I let the block glide over the clear and work it in a cross hatch pattern until it is just turn totally dull before moving up from 400.

Mike

Mike, did you look really, really close afterwards? I totally agree, on my test panels it is super flat. Changing nothing in my process except adding the 400 step makes a huge difference. (huge on a micro level) But, when I move my head to make a straight edge move across the panel I still see a really, really small "chatter" i will call it. its completely consistent everywhere & it appears to be caused from the course grits. My believe at this point is that I can see it because there is nothing else to hide it. The flatter the panel is, the more noticeable the next thing is. Now, I realize I am going waaaay over the top, but if you have done this process I am guessing you know what I am saying. With that being said, this chatter I mentioned looks way better than just blocking with 600, but the 600 first grit doesn't not let me see what looks like sand marks causing the chatter.


here's one of my test panels after the 400 process. Its flat & no visible sand scratches, but has a consistent vibration looking movement on any edge wether its the top of the window (with the fan in it) or a fluorescent tube. Best I can tell its from the 400 grit scratch, but even over sanding with 600 & 1000 still leaves this anomaly & its consistent over the entire sanded area, not random. Maybe this is as flat as whats possible? At some point I will find the limit. Maybe 400- 500, then 800? Don't have any 500 to try that.


I tried to take a movie to see the ripple, but its too small to see. looks flat as can be with zero moment watching the video. can only see it with my eyes.

Mike S
09-05-2016, 12:53 PM
Hi '68

I know exactly what you are seeing. In photography we call it aliasing and is seen when a subject is zoomed in and you can see jagged edges (see attachment as an example). If I look close enough and long enough at the trunk or hood I can see them v-e-r-y faintly on reflections of power lines overhead. When I block with 400 to a dull finish, I use powder guide coat afterwards to make sure all 400 grit cuts are gone when using P600 dry, then repeat the process for P800 dry. It gets wet starting at P1000 but I still use a guide coat up until P1500. For all steps past P800 I use a firm rubber block instead of a soft pad (except for Trizact 3000/5000). Durablock for 400-800 cuts.
When done sanding I use a polish compound with a low-cut blue foam bonnet instead of a course cut compound and a wool pad. What pad are you using? I often wondered if those micro ripples (not to be confused with urethane wave) are due to micro grooves left behind by the polishing pads. IMO, we may be reaching the level of perfection when using a HS clear with just a smidget of 'aliasing' and that may be due in part to the softness of the clear paint film.

Mike

68ragtop
09-05-2016, 02:32 PM
Yes, thats a great analogy of what I see. Very hard to see outside, but fairly easy in my shop with flourecent lights everywhere.
The clear obviously magnifies the lines so they can catch the light.

So here's something interesting.......

More testing:

I just sanded a section of a panel using 400 dry, making sure my last passes were in one direction ////// Then I sanded off my guide coat with 600 wet, final passes in the opposite direction \\\\\ then 1000 grit straight up |||||||, then 1500 & hit it with the polisher. When I look at the surface straight on I can see I am not getting out the 1500 grit scratches, I could still see the "||||" marks. I absolutley expected this, I just skipped the 2000, 3000 this time.

here's the funny part, when I look straight at it I can see the 1500 marks easily. I get down on the panel, now the lines I see are the 600 grit direction lines. it would seem the 600 grit is leaving the "Chatter" I can see in the final steps of polish & the 1000 is not removing it. I jumped back to 800, 1000, 1500, & that helped about 50% but there is still a little bit of 600 directional marks there.

I should digress a little bit. I can't really "see" the 600 scratches. what I see is a "barber shop" light effect when moving the refection the right direction against a fluorescent light tube. just like your picture above, but they have a direction to them.

http://rs1104.pbsrc.com/albums/h324/Mah-hogany/PSP%20Animations/mah_barber-pole.gif~c200
It appears at this point that 600 can correct 400 as if it was never used, but 800 & definetly 1000, lose its ability to to flatten 600,

Seems crazy.

I have one more panel I can mess with, then I'll need to re-clear my experiment panels & wait another week. :D

I am using a yellow cutting foam pad with mystic cut compound what I have been doing is 600, 1000, 2000, 3000, 5000 then polish. Now I realize 800 is going to have to be added into the mix as well as the 400 initial.

Maybe thats as good as it can get?

Mike S
09-05-2016, 03:27 PM
I've seen some very expensive restorations on rare cars and seen those micro ripples. Sometimes I get so close to the panel to look for them that the owner gets up from his seat to look to see what I am doing. :) I like to go no more than 500 grit jumps max with the lower grits. In regards to the grit marks, what brand paper are you using? I'm using Norton gold for 400-800 grits then switch to 3M Imperial wet/dry for 1000-2500 grits.
I haven't tried the sanding pattern you show. I just do a cross cut pattern where I can.
With a 5000 grit finish, at that point it's like "what you see is what you get" being it's so close to being polished so I'll correct any sanding touch-ups at that point instead of waiting to polish it. I've found that by going up to 5000 grit with Trizact I don't spend time trying to remove swirl marks that a 1500 grit cut and compound would produce. I use Meguiar's M1 for the initial polish and follow up with M9 with a black bonnet then wipe the glaze off after it's worked into the surface.

Mike

68ragtop
09-05-2016, 04:22 PM
Just sanded my last test panel. I also do the x pattern normally. I was finishing directionally above to see what was making the marks that look like they had a direction to them.

So, this time I sanded in the tradiditonal "X" in 600, Then when I was done, I did a (no-no) for one pass by lightly & slowly making small circles while following a general direction. Did the same thing with the 800. Then just the conventional "X" with 1000 through 5000. This looks pretty darn good. there are still really small micro ripples, but its flat & no more direction looking marks.
I used a hard block until 5000. probably not necessary though.

I think this is where it hits a wall of what can be accomplished just like you said.

still not sure why adding 800 after 600 helps? I would think 600-1000 would be ok.

I also recently bought a 3401 flex orbital polisher. One of my new favorite tools for final polish. Zero swirls in direct sunlight even using light cutting polishes. that normally would with a rotary.

Mike S
09-05-2016, 04:40 PM
I've given thought to what an earlier poster said about maybe the base texture is what we see at that "micro" level and side angles. I normally don't wet sand the base because it lays flat enough for me to not be concerned. Perhaps, if that is what we are really seeing, then maybe those few cars we see as perfect had their base wet sanded prior to clear coating.
I know at this stage it's splitting hairs and bordering on lunacy (I'm guilty of that!) :goof: , but it is interesting nonetheless. My biggest fear is that having panels as smooth, flat and reflective as mirrors, if we get a rock ding, it will stand out like a full moon on a clear night.
Unless it will be a dedicate garage queen or maybe trailered to shows, or a museum piece that never moves or sees the outside, at this stage we may have hit the limits, as you stated.

Mike

68ragtop
09-05-2016, 05:25 PM
On one of the panels, I cleared over sanded black primer & the ripples were still visible, so I don't think its the base, but maybe.

The other thing I still wonder about are those super small lines that look like little scratches that have no apparent direction.
I can see them when looking at the reflection of a fluorescent tube, just at the edge of the tube. Not at an angle, almost straight at the panels. Have to allow my eyes to focus on the paint & not the light bulb & they will come into view. Kinda hard to focus on because my eyes always want to focus on whats in the reflection. But once I figured out how to look at them, I can find them pretty easy. What the heck are those marks? they are visible in all paints, even un polished oem paints have them, just more hidden in the orange peel. Another ones of those borderline lunacy things I suppose, but they are there and are what separates paint from actual glass imo.

Bob K
09-06-2016, 09:32 PM
One other thing that I have been thinking about is how flat can clear coat truly be sanded to? Itís made of long chain polymers I think, but how consistent is the film? Is it a matrix of hard and not so hard strands? Maybe the act of sanding the matrix actually causes depressions where the weaker components reside while the stronger ones resist cutting. If thatís the case then there is a limit to how flat it can be sanded. I understand that you have seen some cars that were sanded to a very flat condition but are you sure that you were seeing clear coat or maybe a filler that was applied to make it look flat. Fillers on cars that are out in the elements get washed away but show cars can get dressed up every week and never see the weather as it were. Maybe you are looking a good coat of wax or something like that.

Bob K

68ragtop
09-07-2016, 06:03 AM
I think you might be on to something Bob. In the end, no matter how flat, & how well sanded & polished the very outer "skin" of the clear is, the surface still has these little marks that look like scratches, but they are far too random in direction but consistent to be from sanding imo. I think they do grab the light and create the chatter, or aliasing as Mike calls it. on sharp edges. I can look at every panel in any location & the reflection can be like a mirror. But an the very edge of a bright reflection of a fluorescent tube, I can always see these little tiny lines. Not on an angle, but straight at the surface. They are hard to focus on them, but once they come into view they can be seen. they are not sanding marks as far as I can tell. In fact I think sanding marks are really easy to spot & they stand out like a sore thumb on a flat surface. I made a post about these marks a while back when I was seeing them even on oem finishes. Kinda weird. I have had several car guys in my shop & tried to show them the marks & they could not see them. Not sure if these guys need reading glasses, or (more likely) their eyes would not let them focus on something 18" away, when the surface has so many reflected images to dial in on. in my shop, I have white walls & ceilings so when all my lights are on, I can't see much besides light tubes.

Where these marks seem to have a big impact is when you look at a reflection that comes from a seemingly perfect panel that has a slightly inward shape to it. We have all seen it. The area of many panels that actually magnifies & "stretches" the reflective image & those nice, tight lines become somewhat distorted images at just the right angle. that stretch in the reflection really magnifies things & the surface of the paint no longer looks all that smooth. If it really was microscopically smooth, that should not happen.

bmarler
09-07-2016, 10:58 AM
are these like the little micro scratches you see when you first wipe a freshly painted panel for the first time? i have seen these little scratches when using a microfiber towel on a fresh panel. (not necessarily soft paint, but a panel that hasn't been touched since painting.)
maybe its a completelty different thing you're seeing, i'm just trying to understand what it is you see.