The main problem I see with to much clear is solvent pop. Others on this board are more familiar with paint so I hope they'll chime in. The clear, then sand, then clear again method is tricky too because everything has to be cleaned up and dust free before the second clear is applied. I also understand that in some paints the UV protection comes to the surface so you have to be careful not to sand that off or a few years down the road you'll have paint failure.
The guys I know that are looking for perfection shoot three coats. Let it stand two days, sand it flat with nothing finer than P800 wait two days then shoot another three coats, let that set at least three days then start with P1000, then P1500, P2000, Trizact and then polish forever. This is how I do pianos and I stole the idea from a custom car painter. You waste a lot of clear which ends up as sanding slurry but in the end it does look fantastic.
I'm not proud of it,but I have blocked bodywork waves out of clear.
Only takes it from HORRID to "IFFY" though...
Clear untrue reflection
I went to shop recently to help a guy who does very high end restoration who is not getting a true clear reflection in his clear.
The way I Judged his clear is in the reflection of an 8 foot flourscent in the windshield. The edges are clean and crisp, not looking at if there is a bend in it lengthwise but it is a clean crisp reflection on the edges of the bulb image in the glass.
The edges of the flourescent in the clear coat are wiggly. It you look at the line on the edges of the bulbs they do not give a true perfectly straight reflection.
The clear is sanded with " aluminum boards and is dead flat. The problem is not in the top final coat. All I have been able to come up thought wise is that the three coats of clear which have peel in each of them did not blend together.\and the peel in the coats below is showing through.
I am thinking even with the top coat being glass smooth the reflection is not true and crisp cause there are still mountains of clear under the dead flat clear coat. These sitting there are reflecting light off in different directions and giving the untrue reflection.
His bodywork preperation is immaculate. I didn't see the base go on and suspect that if there was some sort of peel type stuff in the base it may also cause this but for now the thoughts on the clear coat is all I can come up with.
He didnt change any equipment and was doing award quality cars for years, this has just come up on this last car he is doing.
Any thoughts on my clear thoughts and if that would be possible.
Warren, that's a very interesting theory but I can't understand how that could be the case since all of the clear coats have the same index of refraction. There shouldn't be an interface between the clear coats which is where I would suspect the distortion would come from. Now you're idea that maybe the basecoat was peeled might be right on track. Here you have two different materials and therefore an interface to distort the reflection. Interesting discussion.
Warren, I have the same theory about the distortion of the clear. I am the one who got this discussion started! It seems to me that If the first coat of clear is not smooth then the successive coats only compound the problem. Clears just do not blend together like the older paints. I think on the Chevelle coming i will put one coat on and evaluate the clearity. If it is not suitable I will stop and sand lighlty the next day or so and proceed. It's alot of work but I want this RIGHT on this car. For a repair it's not a problem since tha factory paint has peel anyway. Thanks!!
Not from my experience.
The reflection you see in your paint is from the surface. In almost 40 years of spraying I've never seen an underlying coat of clear cause problems with the reflection in the top coat. If however you spray an metallic base unevenly or there are surface imperfections that causes a metallic base to lay unevenly you could see through the clear to the problem.
If I have waves in the clear that I want to remove I start by sanding with a hard block wrapped with 800 or 1000 grit sandpaper then switch to 1500 or finer before polishing.
clear untrue reflection
The top surface is blocked dead nuts straight with an aluminum block with fresh paper starting coarse, the preparation below is meticulous. This is the only thing I think can think of, it is just a thought but he told me that a paint rep has suggested the same thing to him since.
if you had a mirror and there were defects in the silver backing it could cause an untrue reflection. I didn 't see the base sprayed or the clear I was just brought in and asked what is going on. It makes it a bit harder. There are no waves in his work under the paint. It is just this slightly distorted image or rather untrue perfectly crisp reflection of the flourescent bulb. I have done the tests and seen this in Black Acrylic lacquer as well, I used to think my RM epoxy was somehow getting a texture transmitting back during the buffing stage and that was showing through the whole deal. You know something going on from the heat from buffing.
This week I get to spend two full days with a massively experienced polisher so will bring this up. Oddly he knows the painter of this care and met him many years ago when he was a Farecla rep for a few years.
If we were both standing in front of the same thing it would be easier to prepare.
Is it still the same to post a photo do you have to use a remote site or with some of the buttons up above is there one that works like Word and allows you to attach from any file??
PS Len thanks for flipping the right switches, I get in easy now, no more turn me away at the border. It pays to know the guys in power.
AFS Sander method
I have the same slight wavy look to the panels on a 49 Pontiac I painted about ten years ago. The car looks good but when you site down the side you can see it. The clear I used was PPG 2001, but I think the type or brand of clear really isn't the issue. I have been using an AFS 21" long board for all my bodywork on my latest project, so I know the base primer will be strait. On AFS' site they show a couple of pictures using their long board and starting with 800 on the clear to get the final clear flat.
Their is also some great shoots of strait black panels on another car.
I think this is the same method (starting with a courser grit) that Len suggest to get that really flat non-wavy look.
Warren, do you know if the clear was all applied wet on wet or was one coat sprayed on, allowed to dry, then the second allowed to dry and then the third.
If it's wet on wet and allowed to flash I can't see how this could be a problem as the coats will bond with each other. If the latter is the case then maybe something weird could happen. As stated previously this sure is an interesting problem.
fun in clear coat land
Well it was all I could think of. For starters since base sprays more like old acrylic lacquer I figured he would not have much peel in there but I didn't see it so i just went with the clear thinking,
I have never heard of this but i did think if he sprays and has peel which he does and hit the second and third with peel on top of that, then levelled it maybe each layer of clear sat like little mountains, well not that bad it is more like 1/4 inch surfaces that are angled off each other or,, not sure how to describe it again only a thought as I tried to come up with some logical thought.
I have only painted one car, base clear black and it came out like glass, no watersanding or polishing. Temp was right, I borrowed an RP K3 1.1 and used too low pressure between 20-28 psi, 15 fluid and it worked excellent.
This shop is struggling with clear right now.
I believe it is not going on well and probably I am going to take my pressure pot and RP down and let him try my set up. For starters he is a real man and never uses an air gauge. He tells me what he runs and and says he does it by sound. SO I told him Devilbiss told me they did a course and invited all the painters up to try a gun and tell them what pressure it was, not one was right.
Guess I am stuck not being a real man cause I like a tac on my truck and prefer having a speedo, and I prefer the digital gauges on the Satas over the needle type on my other guns. At least I can tell him what pressure I am at, when Glasurit asks him what he runs and he tells them it is what he thinks not fact. The first steps starting to find a problem are to look at the parameters.
So Dennis will delve into it a bit more and see what we can find out, I also volunteered to take a panel to the finishing Guru up here, it is over 3,000 miles for me to drive to see Robert and while there are many good reasons to do that (like the 8" of snow on my driveway) not time to do that now.
I tried to see if I could just paste a photo of that car on here but didn't work. Got spoiled with regualar e-mail and how easy it is to do that. One day will have to find out how to work that remote site thing. Something I just noticed as I am typing is this thing cannot keep up to me. Maybe I missed my calling.
Something doesn't jive...
Something amongst the threads in this post, in terms of how to get a truly flat panel w/ maximum DOI, just doesn't jive...
Figuring that we all know, the coarser a grit we block w/, the flatter a panel we get. Following that logic, and using a longboard to block out urethane primer w/ 180 grit (to get things flat), and following it up w/ 400-600 (to minimize sand scratch issues)...has always been the tried and true way.
So WHY...after blocking, and KNOWING that the PRIMER is flat, would someone go ahead, shoot base (w/ minimal fill unless something really goes wrong), then 3 coats of clear (and for some reason think that somewhere along the waym they reintroduced waves into the surface)...seems like maybe sometimes it may happen, but it most cases it doesn't....perhaps, some materials allow users to get away w/ over-application, yet save them from solvent pop.
To me, it just doesn't seem to make sense to shoot 3 coats of clear, over a surface that's been blocked out w/ 180 (and then 400), that we KNOW is FLAT, then sand that clear w/ 800 under the guise of re-flattening it, and then go ahead w/ ANOTHER several coats of clear, and then sand those w/ even finer grits than 800 (at which point, we know we're just riding the surface, whatever it might be).
It seems, that if the materials are applied correctly and consistently, then THROUGHOUT, we'll end up w/ a uniform film thickness, and thus something that looks consistent throughout (whether it be additional single stage leayers, or multiple layers of urethane clear)...there doesn't seem to be any logic to the approach to go through two successive applications of clear and sanding (at least so far as it was previously described) since the approach really adds nothing, and in fact (if the waves are a mystery) would only detract from the final look.
If it's not flat after 180 in primer, it'll never look flat...for sure if after three coats of clear sanded at 800 don't flatten it (and at that fine a grit, why should they), than what on earth is the benefit of successive coats after 800, that are sanded then w/ even finer grits (and hence, less flattening ability)?
I know I've seen plenty an otherwise nicely sanded "flat" finish car, that still has it's waves...I always surmised the case was attibuted to improper colorsanding, and not treating that procedure the same as when using a longboard...true, by the time you are sanding clear, the surface had better be straight, but if the sanding is just focused on a small area and done w/ a small block, why not then have that introduce the potential to introduce (no matter how minute) waves...why not colorsand the same as we block...nice cross hatches, that blend a greater surface areas across the panel.
Now, I'm not suggesting (since I have no way of knowing) that things were done one way or the other...but, given the fact that the occurence of having these waves appear on a surface that has otherwise been meticulously prepared, it seems it's an anomoly in terms of frequency, since it certainly sounds like due dillegence has been adhered to throughout.
I'm curious for an answer, or at least a theory...since I too, subscribe to the tried and true methods of getting things flat (by technique, and more importantly, by the way it finally looks).
The mirror finish idea, when resilvered, is true to mirror's sake, but it's probably not transferrable to the case of automotive finishes, since the base will never be that reflective, and the clear levels the surface (at least, in the vast majority of finishes, that's the case).
So the REAL question is, when colorsanding CLEAR, what IS the technique...too many times I've seen the advocation of just using a piece of paper wrapped around a rubber squeegee, and worked an area at a time, to be the accepted norm...and at the same time, that approach USUALLY works...but alas, we are all individuals, and to that extent may be performing a task that we think we understand to be the same as others are doing, when in fact our own individual approaches may contribute just that much of a difference in the overall outcome, perhaps that's the case. (Maybe 95% of time, that approach works out for the population as a whole...but why not colorsand w/ the same appreciation of the flatness to the panel, that we have when blocking...so what if it's a finer grit, the idea is to unify the larger area, so our eye can pick up on the transitions...as aided in detection by light).
Email the pictures to me.... firstname.lastname@example.org
I'll put them on the web so you can post them.
i didn't have any pictures of this problem. I was there three or four weeks ago and we did a bit of polishing with Sure Finish and his Farecla to try and see if we could solve the issue he had. We could not.
I will get there again not too far away, the panels may have been resprayed but I think he still has the problem so will see. The picture post thing was a general question, I just thought one of the boxes above allowed a photo to be be inserted, I did hold the cursor over it after the post and it says insert image. Can it be done from there or does it have to be on a remote server?
As for the post above that there are a bunch of questions in there and waves are nothing to do with the untrue reflection this shop is getting, all of his prep below is right. It is an untrue edge in the flourescent bulb reflection, stand back and take the bulb out of the equation and it looks great. When Dennis asked if it could be dry between coats that is what I am wondering though do think I asked the painter and he said he did give proper dry time between coats
Will try and get to the shop later in the week and see where things are.
The pictures need to be uploaded from your computer to the web then the URL (web address) can be inserted in the box so that they show on your post. Most pictures on the web have their own address just like a web page, if you right click on the picture a drop down menu will appear, hit "Properties" then you can copy and paste the address in the posting box.