a few ?'s is 180 fine enough + more

[rab]

well im not a body man im more into motors,ect,ect. i just do this stuff for my own personal cars.
i have painted 4 of my cars over the years with just
a nason and omni paints, no clear and had good results, or good enough for me. well it's been a while since i painted a car about 2 years and i can't really remember everthing from the prep stages,ect.

so here are my ?'s please remember these are home jobs done with a old binks spray gun and cheaper paint.

well after putting on filler and sanding from 40,80,100,150,180
is 180 fine enough or do i need to go to 220?

also if i remember correctly i would sand the spots i put filler on with 320 one more time,then just wet-sand the hole car with 600 to scuff it up to get the paint to stick, is this the right/or good enough way of doing things.
thanks

[Bob K]

Yes 180 is good to end your filler on. You didn’t say so I but I hope you are going to spray surfacer over your filler and then block that down with 400 for solid color or even 600 if you are going to spray a metallic color. If you are not planning on using surfacer then check your paint product data sheet to see what it can be sprayed over. I don’t know of any paint that allows application over filler.

Bob K

[rab]

iirc i just painted primer over it.

[Bob K]

That works. You can get the surface a lot nicer using surfacer and blocking but in the end it only needs to be nice enough to suit you.

Bob K

[Harry Phinney]

iirc i just painted primer over it.

There are different types of primers. Some inhibit corrosion and provide adhesion to metal, some are intended to seal existing paint and filler surfaces to provide a consistent base for the topcoats, and some are intended to provide some thickness for sanding. The latter is what Bob K was referring to as a surfacer. There are primers that can fulfill more than one of the roles mentioned above. As Bob K state, if you're leaving your filler sanded to 180 you'll need a primer with at least some filling action and should sand it with something around P400 - P800 wet prior to topcoating. Read the technical data sheets for the topcoats you're planning to use and see what the manufacturer recommends for preparing the surface.

Harry Phinney

[rab]

what about spray can primer, what would you use?

also is wet-sanding the whole car with 600 a good idea to just scuff up the paint, for the new paint to stick too?

any other ideas besides wet sanding with 600?

thanks for the help so far i appreciated it.

[Bob K]

I would save the scuffing for tight spots you can’t sand very well. Airvantage with 600 sand paper on an interface pad is what I do. I find I stop scuffing long before all of the glaze is cut; my arm just gets too tired.

As for rattle can primer, is that really where you want your weakest link in the paint chain. You can get good etch primer in a rattle can but it isn’t cheep, only for a very small application. I don’t even have one. I keep a small can of etch mixed ready to spray and just clean the gun when I do it.

I am not talking about 2k primer surfacer, you can’t get that in a spray can. It needs to be put on with a gun.

Bob K

[rab]

a few more ?'s for you guys.
o.k. here is what im doing,, sand filler with 80 then up in stages to 180 then prime, then what 320 on the primered spots then final 600 wet sand over hole car?

when should i put the glazing putty over my filler (the stuff for filling tiny pin holes)?

also im putting in some new metal in some spots, after i weld it in a grand down the welds what should i use over it, i was thinking of using a short strand reinforced fiberglass filler, what do you guys think?

thanks

[Bob K]

I think you are doing too much sanding on your filler. I try to shape the filler while it is wet so that I don’t have to sand too much off. This means that it’s often needing another application, but that is OK the next application is very thin and smooth. It doesn’t take much work so shape it. I do all the shaping to this point with 80 grit paper on my Airvantage for a single small dent or 80 grit stick on paper on a long board by hand if it’s a large area. Use 3M Dry Guide Coat to get your shape right. Now go directly to 180 and use dry guide coat again just to get the sandpaper marks out if the filler. If you go through so many grades of sandpaper you will make a low spot where your filler is. Don’t do shaping with the 180, it doesn’t shape well. It will follow the contours you already have and just polish them.

When I am done with filler I spray etch primer on the bare steel and then surfacer over the repair area as per P sheet directions. Sand the surfacer with 400 using dry guide coat and then I spray wet on wet sealer just before I spray paint.

Others have there own way, some don’t like etch so they use epoxy. Some don’t like sanding filler with an Airvantage so they do it all by hand. Find a way you like and adjust until you get the results you like.

Bob K

[rab]

a few more ?'s for you guys.
when should i put the glazing putty over my filler (the stuff for filling tiny pin holes)?

also im putting in some new metal in some spots, after i weld it in a grand down the welds what should i use over it, i was thinking of using a short strand reinforced fiberglass filler, what do you guys think?

thanks

thanks bob, any thoughts about my other ?'s

[Bob K]

Sorry, I overlooked your other questions. As for glazing putty, I mix a very small batch of Metal Glaze and apply it to defects that show up when I do the final sanding with180 grit. I try to fill the pin hole or scratch and scrape the remainder off. Then light sand with 180 being careful not to sand so much as to cause a low spot. After that I spray surfacer. I often find more defects in the surfacer after it has been sanded with 400 and guide coat. (I think this is because the sanded surfacer is more like a finished painted part and defects really stand out) I also fix these with a small dab of Metal Glaze being careful to scrape all the excess filler off so only minimal sanding is required. At this point I just spray my wet on wet sealer and then color.

As for welded areas you are right on with the short strand fiberglass filler. I like to make sure that that filler is kept low enough that an island of it doesn’t show up in my final blocking. This may not be true but I have the perception that it is a tougher filler and is harder to sand than the Rage Extreme that I use for my final coat. When you are sanding fillers that have different densities then the softer one sands down faster than the harder one. This will cause a wavy final surface. Sort of like what you get if you keep sanding on filler after you expose a high spot of metal.

Bob K

[glassman]

what about spray can primer, what would you use?

also is wet-sanding the whole car with 600 a good idea to just scuff up the paint, for the new paint to stick too?

any other ideas besides wet sanding with 600?

thanks for the help so far i appreciated it.

If all you want to do is get a new paint job to stick the red Sctch brite pads and some Tide mixed with hot water works like a charm. In the old days TSP and most laundry detergents had phosphates in them and phosphates actually "etched" the paint.

Believe it or not you could actually just wash the old paint with TSP and as long as you rinsed it off VERY THOROUGHLY you could just paint right over it and it would stick forever.

The new urethanes are different so "roughing" them up with a red Scotch Brite pad is necessary. It works like a charm and the paint will stick like grim death. You can prep a whole car for paint in about one hour this way if you bust your butt.

BUT! You have to make sure you scrub ALL the nooks and crannies well with the laundry detergent/water mix and scrubb it all well with the red Scotch Brite pad and rinse very well when you are done. Panel by panel. Don't let the detergent mixture dry on the surface!

It takes off ALL the oil and grease and puts some scratches on there for the paint to grab on to all at the same time. I would think that todays detergents would do the same job even with the environmental standards we have today.

Whenever I did a cheap paint job years ago that is what I did. I even painted my OWN car prepping it that way and it stayed stuck permanently. Washing a car with TSP was proper procedure years ago before you painted it, as long as you let it dry thoroughly afterwards.

[glassman]

a few more ?'s for you guys.
o.k. here is what im doing,, sand filler with 80 then up in stages to 180 then prime, then what 320 on the primered spots then final 600 wet sand over hole car?

when should i put the glazing putty over my filler (the stuff for filling tiny pin holes)?

also im putting in some new metal in some spots, after i weld it in a grand down the welds what should i use over it, i was thinking of using a short strand reinforced fiberglass filler, what do you guys think?

thanks

Fiberglass in ANY form does NOT stick to bare metal permanently. It will for a long time but depending on where it is applied and the flexing of the steel it WILL break loose eventually because fiberglass and metal flex at different rates and expand and contract in temperature rates differently.

After doing metal work and prepping the steel correctly a coat of PPG DP-40, if you can buy it in your area, seals the metal and you can apply any body filler over it. Read the directions for dry time before applying body filler over it.

DP is the best and you can put almost anything over it including filler, primer and paint. Once it's dry you can hit it with a hammer and it doesn't chip. At least it didn't the time I tried it.

I used DP for years and it never let me down. It's incredible stuff.

[BradNes1]

He's talking about fiberglass reinforced filler not fiberglass mat and resin and yes the filler will stick very well to the metal since it is pretty much the same filler resin as body filler just with short strand glass in it for reinforcement.

[glassman]

I wouldn't use the "tiger Hair" type products on metal either. First of all they don't flex or expand and contact the same way metal does either. A high quality plastic filler is all he needs for covering up welds and such. It's far more flexible and much easier to shape.

That fiberglass filler is good for some things but leveling a panel isn't one of them. Sure it will work but it's a bear to work with and there are other products that aren't as difficult to deal with in that respect. The other problem with it is that it can't be pressed into small imperfections the way a high quality plastic filler can. That quality can reduce any problem you may have down the road with moisture or air trapped in an air bubble.