Thread: wet sanding?? painting ??

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Hey Gang,
My buddy and I are redoing a 1957 VW bug.
sort of a hot rod for my grandson
balanced 1600cc motor 12v alternator and newer transaxle and bigger brakes. New floorboards. new rubbers and seals- new headliner- gauges-oil pressure vacuum volts and Cylinder Head temperature - no gas gauge just a reserve fuel valve
A little more jam than the stock 36hp crashbox with 6volt.

We both are green when it comes to painting and would rather get greasy but this a bit of a challange.

The body was sandblasted and now we have most of the dings straight and a very light skim of mud on the roof.

When do you wet sand the bare metal and bondo?
What keeps the body from rusting ?

you clean the metal before painting the etching primer

do we spray a filler primer next
is there any more sanding between these stages?

we will be using DuPont L-99 black

How many coats of paint do you guys do?
.
Is there anyway to tell if we have enough coats?

thanks
hank

best wishes for the new year

you dry block it all the filler to 120 grit or180 use a guild coat over the body filler. use a spray can of black paint very light coat and block this off with a sanding block with dry180 or 120 this will tell the hi and low spots and 36 -80 grit scratches if you can not sand the filler down it may need more . when you get of this point you may want to use a self ech primer and then a filler primer. i will try to make this short .you should try to fix all dent grinding marks etc be for you prime. any thing you try to bury with the primer may come up in the finsh. the more you guild coat it and block the better it may be if it the body work is good . put down 3 coats of filler primer let it set up good .spray a guild coat and block all black off wet sand with 180 on a block try not to cut in the filler or the steel dry off if you cut thru. re prime two coats if not re guild coat .sand with 220 wet sand paper now at this time if you did not cut thru you are about to. dry off good and use wax and grease re prime two coats now sand with 320 re guid coat wet and use a not to hard sanding pad or a thick paint stick and then go to 400 wet with a soft pad and you can go up to 600 wet . you may need to spot prime if you break thru so try not to over sand it takes many years to do a good paint job and when you get good at it your arms fall off from all the sanding

Thanks Pat
I've cut and pasted your reply and I'll read it over a few times
thanks
hank

We all do things differently, so here are few differences that I would do from what Pat outlined.

The only time that I “wet sand” is before rubbing and/or polishing; then this is dependant on what type of paint you are applying. There are a lot of people that wet sand before paint, but I never did.

When I worked in a body shop, we finished all of our plastic (bondo) with 80 grit, then it was primed. So initially, the plastic was sanded with 36 or 40 grit and the final sand was with 80 grit. You could take it down with another sand (higher grit), if you wanted, but it mostly depends on what kind of top coat you are planning. It is easier to smooth the metal with plastic, than it is with primer. The name of the game is, get it as smooth as possible before priming. If the edge on your plastic into the metal is abupt, and not gradual, then you probably have a high spot, which would show on the metal as being shiny or the plastic is high.

I haven’t painted much in the last 10-15years, so I haven’t had a lot of experience with the newer paints/systems. But fundamentally the processes should be the same.

Guide coats that I use: I usually just use a different color of primer, so the sand paper doesn’t get clogged up with paint. I got used to using a light colored primer (grey) and a dark (red oxide) for the guide coat. Just throw some other color primer, thinned way down, in a cheap or extra gun and then mist coat over your primer.

there is many ways to do this. do it the way you want. but if you sort cut and try to fill 80 grit it will pop up this way .i have told you that will stands the test of time been doing all my good paint jobs this way for over 25 years .you can dump the primer on it and d.a it flat with 220 to 320 and seal it and paint it. if you guild coat you do want to mist it on and use black lacquer in a spray can if you can find it you do not paint the black on just a very very light coat or it will plug up the paper and that is why you wet sand

here is the way I do the paint and body work.

if it's been blasted and there is bare metal exposed, use a cheep primer because you will sand it all off anyway.

use a DA sander with 180grit paper go over entire car .keep a something to mark with in your pocket, like a lead pencil. while sanding stay away from edges, keep the sander flat dont get it up on its edge, mark hi/low spots as you find them . after you go over the car . take down all high spots, mix some filler to go on low spots. block sand with 80grit or 100grit. blow of sanding dust and reprime the entire car. get a couple spray cans of black very lightly spray the car ( I use a cheep black laquer primer in spray cans).

use the DA again with 220 grit and sand over entire car. again dont get on the edges. for areas the DA cant get to you must do by hand.

while sanding over the car, mark any spots you need to fill or take down, do them the same as before, with filler and 80 to 100 grit paper sanding is very important at this point the 220 will help get scratches out. so after the lows have been filled and blocked down with 80 or 100, switch to the 220 and hand block the same spots and make sure you feather the surounding areas. prime the entire car with a self etching primer.

next use 320 or 400 wet or dry paper, wet sand by hand . keep you'r hand flat dont apply to much pressure just let the paper do the work. keeping the paper wet and sand the entire car . dont try to take on the entire car at once you can do a section at a time this will give you breaks in between.

after the wet sanding wipe the car down with a damp rag and towel dry. while wiping the car down with the wet rag this is where you should be looking to make sure you didnt miss anything.

this is where you will make or break a good paint job.
next prime again . but this time you will just scuff the primer up a little . with 600 grit up to 800 grit. wipe the car down. and its ready for the paint to go on.


as for spraying the paint. everyone devlops there own mathod, what works for one may not work for you,
I keep a test panel in my paint boot to test my paint gun on before I spray the car.

this really can not be told on a post. i could fill up the hole form on why to do it one why and not . i could spend more time on steel and how to get it right with out filler or how to tell you how to lead it if you want. i have done it many ways and have painted boats air planes car truck cranes you name it i have painted it and have many show quality paint jobs and have used all types of paint so there are many ways to do this but i can tell you i have stuff out there that looks like the day i painted it over 15 years old so it is all in the prep .you can not get some thing flat with just a hand or a d.a it will need to be block or it will be choppy i can get things good with a d.a but it is a good d.a and this is not for the first timers

Originally posted by TOW'D


We both are green when it comes to painting and would rather get greasy but this a bit of a challange.

The body was sandblasted and now we have most of the dings straight and a very light skim of mud on the roof.

I'll probably get thrown out for this, but it is very hard to do body and paint via email.

From what I've read, in the responses, there is good information there. Everyone is trying to help. There are books out there and sources on the net about painting, do a Google or Yahoo search, here is one:
http://www.neilslade.com/Papers/Painting.html

Gather as much information as you can, everyone that you talk to will do things differently.

Remember paint doesn't like grease, so wash everything well.

Check out this site for great paint and body info;


http://www.autobody101.com/

First thing you have to do is WASH it down !! Sand gets blasted into the metal, so you need to get that out- I use rubbing alcahol because it's a lot cheaper than metal prep & the same thing.
Then you prime it with etch primer & block to find your lows & high's. Mud the lows- work down your putty & reprime with a good CATILIZED primer surfacer- block this down again to check for highs & lows, fix any that you find, and glaze any mud work with Iceing & sand & reprime with primer surfacer. 3 HEAVY coats & then crosscut this with 180 paper & then 320 paper. Wash it down with a good prep wash & seal it with a good CATILIZED sealer - 3 coats & let sit for a day to cure up. Wet sand this with 600 grit paper, wash, paint & clear. Cut, buff, glaze, and reassemble.
Piece of cake.......lol

tow'd, Totally confused now? The only thing I will add is to use a catalyzed urethane primer. This is a great barrier coat, preventing interaction between the paint, and what is under the primer.

Also, it is very stable. If you have buried heavy scratches, and rough edges on bodywork, it should not come back later. I have zero problems using this. Use at least two coats, and up to 5 or 6 if it's really wavy.

You won't even need a sealer, unless you sand through, or glaze low spots, during the blocking process, or if you want to start with a color closer to your paint color.

Wear a mask meant for catalyzed paints!

Good point there HP, there's nothing worse than subcoat failure....well, except falling over into the wet paint- 'bout the same work to repair.
Been there - done that, used a "cheaper" primer, sealer failed, stopped after the first color coat, resanded * re glazed because the paint ate it, re-primed with quality primer, re-sealed with proper coats of sealer, re-painted. Cost of cheaper primer : 400 bucks & 10 extra days....what a savings.

yes wear a mask this stuff will kill you . make shure you keep it in a zip bag so it will not break down the filters in the mask

Originally posted by hambiskit
Good point there HP, there's nothing worse than subcoat failure....well, except falling over into the wet paint- 'bout the same work to repair.
Been there - done that, used a "cheaper" primer, sealer failed, stopped after the first color coat, resanded * re glazed because the paint ate it, re-primed with quality primer, re-sealed with proper coats of sealer, re-painted. Cost of cheaper primer : 400 bucks & 10 extra days....what a savings.

I'm assuming the other painters here will agree, that you need to find products that work every time. It is a lot of hours and materials cost invested, to take a chance on something that isn't reliable. Cheaper does not mean it's a better choice!

I had a guy working for me once, that wanted to try a new paint product on every job. I would hear comments from him like "That worked pretty well! Next time lets try something different." Obviously, I put an end to that way of thinking! :-)

Go with products that these guys have used successfully.

A painter that I used to work with would say, "When working with chemicals, the results are sometimes unpredictable". There are so many variables with painting, when you do everything right in the preparation, you have a better chance for success.