Finishing-Wet Sandpaper

[marvSRG]

I know the general prime-sand-prime-sand with increasingly higher grit sandpaper priming method, but I know "wet sandpaper" is used in those really nice finishes. What is it, how does it work, and where do you use it?

'Preciate it.

 

[sandman]

Wet sanding is a really cool thing.

To begin with it is "special" wet/dry sandpaper and it will say it on the back. Usually it's black sandpaper.

You sand by getting the paper wet and keeping it wet. It flushed all the sanding residue off of the paper and it really cuts great! Much faster that dry sanding.

You just have to do some thing differently.

You cannot...or should't...wet sand an unpainted bare body tube or wooden fin/nose cone...DUHH!

Don't get water into the open end of the tube...another DUHHH!

Keep dipping the sandpaper into the water to rinse the sanding residue off (the water will turn the color of the paint).

As the water drys on the surface while sanding it will form a paste the color of the paint...keep a clean cloth handy and keep wiping it off (paper towel works).

You will have to use a tack cloth when the water drys off to get the dust off.

It cuts fast! and the sandpaper will last longer then you ever imagined it could.

Try it! Finish with some 600, 800 or 1,000 grit...baby butt smooth!

Then do a final "wet" coat of paint...It's a good thing.

sandman

 

[limd21]

Those in the show car/motorcycle world go even further than what Sandman describes. In that arena, the final "gun" coat of paint (usually a clear coat of some sort) isn't even good enough. To give you an idea of how picky these guys are, they consider the paint on a factory BMW/Audi/Lexus - which is a gun coat - to not be good enough to be show quality. They will take the finest grit paper - sometimes even finer than 2000 grit - to wet-sand and flatten out the final coat of paint. It will look dull at this point - its just been sanded after all - but it will be perfectly smooth and flat. To bring back the shine, a final machine polish is done with various compounds and polishes. It's just amazing how good these finishes can be. If you've never been to a custom car/bike show, I'd recommend it just to see how good the art form of painting can be!

All this said, I like good finishes on my own rockets, but I've never gone to anywhere near this level. I use wet-sanding primarily to deal with defects and painting errors. A decent sprayed on top-coat is all I usually want or need.

 

[Ryan S.]

I just tried it with 800 grit, had a wet towel and kept the airframe wet. I was amazed at how well it smoothed it and cut down the lumps....the 120 I was using before was working as well and that was 120! I had used a water based primer so I think the dust mixed with the water and dried in the low spots

 

[marvSRG]

Great info, guys! So the is the wet sanding only with the actual paint coats (colors) and not the primer? Or can you do it with the primer, too?

 

[sandman]

You don't need the fine finish on the primer but...220 grit wet sanding does a super job on the primer.

Be careful! 220 grit wet/dry cuts real fast! DO NOT go through the primer to the tube.

You don't want to get the bare cardboard tube wet.

Another trick is to alternate primer colors...or is it colours

When you sand the primer the bumps show up as the color below.

Just make sure both color primers are the same brand and compatable.

sandman

 

[marvSRG]

Thanx sandman!

...and you were right...it's colors

 

[cydermaster]

Originally posted by sandman
or is it colours

Its colours where I come from

Thanks for the tips, I've been wondering how you were supposed to 'wet sand', and this thread is answering my questions.

 

[JoJo]

i wet sanded my deuces wild. it looks great. trust me it's worth the extra time

 

[sandman]

I don't want to name names but....we have a member here in the forum...obviously a bachelor, that wet sands in the shower.

A married man could NOT get away with that!

sandman

 

[Chr$]

For a good finish, I wet sand, then clean with damp towel, then don a pair of latex gloves and wipe all the skin oil off with alcohol dampened soft rag. Then clearcoat. The skin oil from your hands will cause some paints and clearcoats to bubble up.

 

[moocrew]

Great thread! has answered many of my questions about wet sanding.....
but where is it possible to get fine grit paper....uh..above 1000?

 

[rocketsonly]

I'm not sure of the exact grit, but go to your local hobby store, Michael's, or Hobby Lobby and look in the modeling section for Testors sand paper. It's rather expensive for sand paper, like $2 or $3 for 5 different 3x4in sheets. Actually, it was intended for several uses with wetsanding because itstead of the normal paper backing on sand paper, this one uses plastic. The roughest sheet is actually pretty fine, and the finest sheet feels almost like smooth paper... it's REALLLLLLY fineee.

 

[Stymye]

annother good place is the auto parts store ,,they have a six pack (3m brand) that has 2 of each 320,400,600 grit in full sheets..it's around $5 and lasts a very long time

 

[Wingarcher]

I've gotten 1000 and 1500 grit 3M products at a national chain type car parts store. The name has completely escaped me at the moment..

I sand the filler and tube down with 220 and usually 320/400. Then a decently heavy coat of primer. Wet sand it, almost going through in places. I use 400 or 600. The 400 cuts a lot faster, perhaps use it, and then smooth it out with the 600 grit. Prime again. This time sand with just the 600, but still make sure you take about 1/2 off. Now..... paint. I use a waterbased latex shot through an airbrush... anyway, a Krylon gloss clear over that, gets wet sanded, after about 2 coats. That's with the 1000 or 1500, depending. Then hit it with a "wet" coat of the same clear. Now you're done with the wet sanding.
My secret weapon is Novus Plastic Polish #2. It's a wet compound that "takes off scratches" (tiny ones!) and has a wax in it. Dribble it on, rub it around until it drys, and buff it off. You get a slippery surface that won't take a fingerprint.
All the work, though, is in the wet sanding.

N

 

[lalligood]

Originally posted by wingarcher
I sand the filler and tube down with 220 and usually 320/400. Then a decently heavy coat of primer. Wet sand it, almost going through in places. I use 400 or 600. The 400 cuts a lot faster, perhaps use it, and then smooth it out with the 600 grit. Prime again. This time sand with just the 600, but still make sure you take about 1/2 off. Now..... paint. I use a waterbased latex shot through an airbrush... anyway, a Krylon gloss clear over that, gets wet sanded, after about 2 coats. That's with the 1000 or 1500, depending. Then hit it with a "wet" coat of the same clear. Now you're done with the wet sanding.
My secret weapon is Novus Plastic Polish #2. It's a wet compound that "takes off scratches" (tiny ones!) and has a wax in it. Dribble it on, rub it around until it drys, and buff it off. You get a slippery surface that won't take a fingerprint.
All the work, though, is in the wet sanding.

Wow. You *like* sanding, don't you?!? haha I bet your rockets shine though!

The Novus #2... What a great idea! And I just happen to have some for my pinball machine For anyone interested in getting some, try Happ Controls or a local (video) game distributor.