Going to paint my spoiler this weekend,and trunk lid the next weekend. I tried wetsanding on a small little piece for my sisters car and I just sanded most of the clear off, I think it needed a more layers of clear and maybe a higher grit of paper (was wet sanding with 1000 grit).

How many coats of clear and what grit do you use when wet sanding? How many layers of clear should be on before wet sanding to get that glassy look.

Thanks.

 

I would think you'd definately want to be higher than that grit, although I have no first hand experience. I was just told to wet sand (*if necessary* I don't think it will be) with 3000 grit to get spray paint off a car's paint (not mine) on autopia.org, so I think that was definately too rough. You're painting it yourself? Forgive this question, but I'm assuming you don't have a paint booth, so what's your setup?

 

I also felt 1000 was too abrassive. I have 2000 grit paper, but will get 3k or 4k to be on the safe side.

I'll check out the autopia.org and see what other info I can find.

I dont have a booth (unfortunately) so its going to kinda be a backyard like setup, hang the spoiler in a well oriented fashion to get get run off, and so that I can apply even coats to all areas. I will take many pics, hopefully it turn out well. This is an exercise for me/learning experience.

 

Definately do that, what are you using for paint?

 

Clear coat should be 2 nice even coats.
You can do 3 if thats what it takes you to get it layed on evenly.

Wet sand gently with soap and water and 2000 paper. Fresh paint will polish back up with a nice machine polish, you wount need compound. If you do use compound, make sure it's a light cut. If it's heavy cut, you'll go right through fresh paint.

 

you dont need to use soap when wetsanding. 2k or 2500k is good enough but when you spray the clear spray at least 3 coats and make sure they are even or the clear will either run or there will be alot of orange peel. now when you are sanding you will feel the clear become smoother and the orange peel will start to go away and that is when you need to stop or you will wet sand through the clear. hope that helps.

 

Thanks for the great advice, I already have some 2k grit sandpaper, duplicolor clear, black paint, and sandable primer.

I will allow suffient time for each coat to dry. I'll put about 4 coats of clear, and use a spray bottle and the 2k grit sand paper to get a nice glassy look.

I'll grab some pics, as I'm working and hopefully all will turn out well, with minimal errors.

 

If you sanded through the clear, then you sat at that one spot too long. 2000 grit is all you need, that and some water. 2 coats of clear is pretty much the industry's standard unless you start going customer paint jobs. Sand in a circular motion as well. When compounding out the spot, again, keep moving the buffer around or again you will burn the paint. Do not be afraid to use a good amound of compound-not enough compound and you will burn. Mos timportant, make sure your pads is clean, esp of old compound and never rest the buffer face down. The old body shop saying goes "You burn as you learn" hehe.

 

Good advice synki, In previous learning exercises I didnt wet sand in a circular motion, will definately try that this time around. A spay bottle for my water will probably be better, as I was before just kinda pouring and sanding, and the water would run off some, a misted on water should be better plus dunking the sandpaper in water to insure its wet also.

I may not compound the spoiler, but thats great advice for compounding, and I certainly will need it when I do my trunk (assuming this all goes well with the spoiler).

 

This is more complicated than people are telling you. I did my own spray jobs for years and enjoyed it.
1. There are two types of clear-over. Acrylic and two-pack.
Two-pack is chemical setting and tricky to handle. Hard to sand. But very hard and is high build, two coats are plenty. But to sand it, you need a proper belt sander.
Acrylic is cheaper and much easier to use. I used to use up to 8 coats of clear-over with acrylic, but then, I was burying Metalflake(tm). The more clear lacquer, the more 'glass' effect.
Unfortunately a high build, while giving a great glass effect, leads eventually to cracking (crazing) because the finish isn't very flexible.
2. The recommendations on wet sanding are nonsense. When you finish the clear over, let it stand for at least a couple of days to harden off. Then sand with 400 grade wet-or-dry, used wet. Don't be excessive about it. Then move to 800 grade by hand, and then finish lightly with 1200. After that you need a buffing pad with compound to get that mirror finish. I end up with metal polish if I am after that Rolls-Royce look.
Do not apply any form of wax or silicone polish until the car has stood for several weeks.
It's all practice, basically.

 

My clear is from Advanced auto parts so I'm sure its not the two-pack.

Wouldnt 400 grit be too abbrasive for trying to produce a nice mirror like or just smooth looking finish? Isnt that what the higher grit papers were for, to smooth out the surface? I 400 wet would make a smoother surface than 400 dry, but that still sounds too abbrassive to me.

 

I would take Tom's advice since he does this for a living and all of his work, from what I have seen, is very very good.

 

- No. I always started with 400. The whole idea is to use the 400 to make sure that there are no pimples/dimples/embedded insects/whatever. Then you go progressively smaller, which polishes out the tiny scratches left by the 400. Well, you can go straight to 800 if you want to spend days over it!
One thing I forgot to mention: do NOT make circular motions with the abrasive. Sand in straight lines following the contour of the car from front to back. An orbital sander is not good for doing this kind of work, and a disk is worse, like committing murder on the finish. You will need a 3M rubber block for the hand sanding. Also be careful to get the right viscosity on the lacquer, you don't use it straight from the tin unless it is pre-thinned. Think I used about 35 PSI and the nozzle was big enough to do an entire side in one pass.
I used to buy acrylic by the gallon, I used so much of it, Metalflake requires many coats because the flake 'stands up' and must never be touched by the sander. Again, with clear over, you want to use enough clear so as to avoid breaking into the top coat. For me, that would probably mean 3 coats of acrylic because I spray it pretty thin to avoid orange-peel.
I will say one thing: I got a taste for doing this. It is very fun except for the prep work. BUT I didn't have a proper pressure-fed mask and I ended up with high sensitivity to nitrates as a result of inhaling too much of it. Take care of your lungs. In particular NEVER spray 2-pack without protection, your lungs can turn into cement bags.

 

wetsanding spray paint? never heard of it.

but i would imagine the theories and practices to be the same.

spray your clear heavy- 'shoot for the shine, **** the runs' as they say. when you spray clear it should be wet on wet, ie an overlap of 50% for each pass. when you spray- get the rhythm and timing down first. your passes should be paced so the clear sprays flat. less orange peel means less sanding.

when the paint is fully cured, you can use 1000 grit, 1500 if you want to be safe with a sanding block. soapy water is not necessary, but helps. as long as the water where your sanding is turning white- thats clear. if it helps, dry the panel every so often and wait for it to dry/haze- that will make orange peel and places that need more sanding evident.

i dont know much about this 400 grit nonsense, ive sprayed boats with gelcoat and use that on finishes 1/8" think.

 

Obviously you've never worked in a body shop.

400? Your absolutely nuts.....
We don't even use 400 to get old painted surfaces sanded down to primer.
Never sand fresh paint with anything less then 1500, unless you plan on respraying it again. Even 1500 is severe and will leave hard to remove sand scratches.

Proper wet sanding fresh paint, by fresh I mean a week or so old, only needs a good machine polish to bring it back to a perfect mirror finish. Compound is really only used on totally cured paint to cut or even the surface, removing scratches and heavy oxidation.

 

If you've got HEAVY orange peel, then 1000 is okay, then work your way up to 2000 or 2500 (wet) and then use machine glaze and a foam pad on a random orbit buffer to finish the job..

If you don't have a lot of orange peel, then start with 2000 or 2500 and then polish/glaze after that.

If you're just doing the wing, you don't have a ton of surface area to sand, so go ahead and squirt on 3-4-5-6 coats of clear if you want. thicker is better as you can always sand it off. too thin and you rub through the first time you hit it with a buffer... When spraying let it sit just long enough between coats to almost-flash between coats... you want it to thicken enough so it won't run, but you don't want to let it get too dry between coats or the clear can peel off... I'm sure you've seen those cars driving around.. uke: