Sanding process

[Dankidus]

Ok, so I laid down a coat of enamal primer on a few big parts and let it dry for a few hours. It looked great but I saw a few tiny bumps in it so I decided to take some paper to it. Using 1500 grit 3m wetanddry I saw some imperfections forming due to the sanding, so I switched to 2000 and it didnt really help any. I decided "Well maybe it needs water?" so I used a little water on the paper to lubricate it and started pulling the primer off. Coming back to it a few hours later I can still see the swirl marks from the sanding where there is still primer... Do I just need to keep applying coats of primer until it looks good? What if a particle of dust gets in it while its drying? I feel like an idiot but I've never painted anything before and I wish I knew the process in detail from start to finish. Could somebody please help?

[Guest Gramps-xrds]

Throw that can of enamel primer in the trash. Strip it and use a sandable lacquer base primer. You can use lacquer primer under enamel or lacquer and you won't have that problem again.

[Zoom Zoom]

If the primer is enamel and if it does not say "sandable" on the can, don't use it.

[MrObsessive]

I second what Gramps has to say about that primer. If it's Testors primer..........DON'T KID YOURSELF AS IT IS NOT PRIMER!

My recommendations for good sandable primers as Bob mentioned are these...........

Duplicolor

Tamiya

Plastikote

Krylon

As Bob said, it must say "sandable" on the can in order for it to be effective on plastic. My normal way of applying primer is to decant the paint into an airbrush jar--------then airbrush it. I'm not crazy about cans of any type..........it's a paranoia thing with me.

HTH!

[Dankidus]

Mistake understood and advice taken, guess it's back to the store for me! It is Testors gray primer, doesnt say sandable, and I got it because it was right under the models at Hobby Lobby, lol... Assumptions are the mother of all f'ups I suppose. It looks great but if I cant sand it... oops! Good thing I only did it on the interior and not the body.

I wish I could buy an airbrush but I just dropped a couple hundred bucks on everything and money is tight atm... Maybe in a couple months if business picks up I'll get a great airbrush set!

And thanks for the replies everybody!

[hellonwheelz3]

I know i'm still a noob, but if i may add my 2 cents in here, I use the polishing pads from micromark that are about 2x2" and maybe 1/4 " thick. Here is the link.

http://www.micromark.com/SOFT-TOUCH-PAD-SET-SET-OF-6,7787.html

So far I have not used sandable primer and have it down to a glossy, smooth as a baby's butt finish. Just my opinion.

Mistake understood and advice taken, guess it's back to the store for me! It is Testors gray primer, doesnt say sandable, and I got it because it was right under the models at Hobby Lobby, lol... Assumptions are the mother of all f'ups I suppose. It looks great but if I cant sand it... oops! Good thing I only did it on the interior and not the body.

I wish I could buy an airbrush but I just dropped a couple hundred bucks on everything and money is tight atm... Maybe in a couple months if business picks up I'll get a great airbrush set!

And thanks for the replies everybody!

[BARBER]

Throw that can of enamel primer in the trash. Strip it and use a sandable lacquer base primer. You can use lacquer primer under enamel or lacquer and you won't have that problem again.

I picked up some paint from a auto body supply store and is a single stage enamel, I can safely spray this over, say Dupli-Color's primers, either sandable, filler, or sealer?

[Wayne Buck]

I picked up some paint from a auto body supply store and is a single stage enamel, I can safely spray this over, say Dupli-Color's primers, either sandable, filler, or sealer?

The best thing to do would be to try it out.

Pick yourself up a pack of plastic spoons and paint one just like you would paint the model.

If it turns out ok, then you should be fine.

[BARBER]

^I'll give it a shot, Thanks.

[Dankidus]

Ok I feel really stupid in asking this one, but how do you tell if a paint is lacquer or enamel if it doesnt say it on the can?

[wgflatliner]

my new process (thanks to donn yost's dvd set - hehe):

before i primer, i sand off the mold lines, and wet sand the body with the polishing kits (1,500 grit to 4,000 grit along with 3 separate cloths at 6,000 8,000 and 12,000.) Make sure you start from 1200 and work your way to 12,000. once this is done, the plastic will look shiny, which is ok. you don't have to spend a lot of time per grit, and you don't have to use much pressure to get it right. The best thing to do is get a practice body to practice on.

metallizer's spray paint works good for a primer.. you will likely see a verrrry smooth primer application if the body prep is done right. After the body is straight and primered, then start your color paints. when it's done, do the same wet sanding process, then follow up with novus 2, then novus 1.

i'm kinda tempted to personally go through the whole wet sanding stage after every coat of primer and paint just to ensure a smooth paint job.. not sure if that would be wasting my time though :|

if you want more tips on this kind of stuff, i strongly recommend ordering Donn Yost's dvd set. it's definitely worth it.

[astroracer]

my new process (thanks to donn yost's dvd set - hehe):

once this is done, the plastic will look shiny, which is ok.

Actually, a shiney surface for primer is NOT what you want. The primer HAS TO HAVE a certain amount of roughness, or "tooth" in the surface for it to adhere to. Spraying it on a polished surface will not give it this tooth and this affects the adhesion. All of the work you are doing "polishing" the plastic should be reserved for the primer. The primer serves two purposes in an automotive type paint job. The first is as a substrate for the glossy top-coat to adhere to. The second, and most important, is as a "leveling" medium to smooth out all of the dips and waves inherant to any molded surface. I have never sprayed primer over a surface smoother then 800 grit... 600 is usually the "industry" standard.

I also use a lot of Scotch-Brite. If I am not leveling surfaces and just roughing a body up for the 1st coat of primer the gray SB does an outstanding job of getting into all of the little nooks and crannies on a model body.

Mark S.

Edited February 26, 2010 by astroracer

[wgflatliner]

Actually, a shiney surface for primer is NOT what you want. The primer HAS TO HAVE a certain amount of roughness, or "tooth" in the surface for it to adhere to. Spraying it on a polished surface will not give it this tooth and this affects the adhesion. All of the work you are doing "polishing" the plastic should be reserved for the primer. The primer serves two purposes in an automotive type paint job. The first is as a substrate for the glossy top-coat to adhere to. The second, and most important, is as a "leveling" medium to smooth out all of the dips and waves inherant to any molded surface. I have never sprayed primer over a surface smoother then 800 grit... 600 is usually the "industry" standard.

I also use a lot of Scotch-Brite. If I am not leveling surfaces and just roughing a body up for the 1st coat of primer the gray SB does an outstanding job of getting into all of the little nooks and crannies on a model body.

Mark S.

just go buy the DVD's. thanks.

ok i'll be a little more positive with this.

edit: i understand that primer has to have a certain amount of bite for paint to stick to it. I am simply speaking from watching the DVD, and applying that exact technique to a BMW i'm working on right now. i didn't sand the primer as it was smooth anyways, thanks to the body work. I did scuff up the plastic as i had outlined earlier, and the primer laid on super smooth, so i'm speaking based off my own experience.

Please don't take everything i say into offense, and please don't feel that you need to step in and try to "correct" me on everything, especially suggestions. Nobody else on the thread even attempted to explain the WHOLE sanding process but myself, and when i do, people like yourself just jump in and say i'm doing it wrong. Wait until my BMW is done, and we can base my wrongness on the results of the paint job.

sound fair?

Edited February 26, 2010 by wgflatliner

[Blake Rogers]

!!!!THIS JUST IN!!!!! Mark .S. and Mark .T. battle it out to see who knows how to sand!!!!!! but who will reign over the other ?? only time will tell..........

[meaneyme]

Just because the guy sells a few DVD's doesn't mean his method is the correct one, we all have our ways of doing things. One thing is certain, you must have a slightly rough surface so that the primer sticks well....