questions about surface prep, priming, sanding and painting

[t_tail_boy]

1. Should all plastic model bodies be primed?

2. Can enamel and lacquer base paints be used over the same kind of primer?

3. What grit sandpaper should be used to prep the bare plastic surface for the first coat of primer or paint if primer is not used?

4. Should all sanding be wet sanding?

5. Should a wet-sanding be done after each and every coat of paint or primer?

6. Should clear be wet sanded even over decals?


I plan to build a model heli, a model jetliner and a model Kenworth truck. I have to be careful so as not to sand out scribe lines or details as rivets in the body.

I plan to build one kit at a time starting with the truck, then the jet and then the helicopter. I have plenty of patience as I have a couple hundred dollars now invested over spay paints and four model kits.

I have Model Master Plum Crazy Metallic Lacquer as the base paint for all three models. I've elected Testors Glosscote lacquer to cover the waterslide decals. I'm not a modeler who enters competitions but just want nice-looking models for shelf dispaly and hanging from the ceiling for the aircraft.

Oh, by the way, I'm just rattle-canning, no airbrushes. So I need a compatible rattle primer for what I have already. Any suggestion for primers?

 

[urumomo]

1. probably . Usually better adhesion and more uniform results .
2. Yes . Static scale models enjoy an easy life .
3. No sanding needed unless you need to address areas that needed putty . ( or general removal of seam lines etc )
4. Up to you . Wet sanding is more efficient but not necessary .
5. No
6. No

Good rattle-can primer for polystyrene kits is the lacquer based Tamiya Surface Primer .

Or , good adhesion from Rustoleum Painters Touch ( 2X ) , which are enamels ( alkyd ) formulated for plastics as well as other surfaces . ( just remove and clean the spray nozzle with turpentine or mineral spirits immediately after each use or you wont be using that spray nozzle ever again .

Lacquer , automotive primers from various makers .

 

[t_tail_boy]

Thanks I have Tamiya Surface Primer on order from amazon.com, light gray for darker colors like my Plum.

 

[ArtChromer]

Just to throw another opinion at you,

I use whatever I can get my hands on for the least cost. Now I am just starting out again, and am ok with less than stellar results, as I am just getting my bearings back in this world. I try to find enamel rattle cans that say OK for plastic, but I have yet to run into anything that doesn't adhere to plastic, from Rustoleum, Krylon or any housebrand from walmart/lowe's/depot. Results may very, but the risk is worth the cost. To that point I have also not had the plastic ruined by paint either. I imagine some lacquers may on bare plastic, but an enamel primer ought to keep you safe. I can't see myself ever using anything from Tamiya, simply based on the cost.

I use 500 and 1200 grit wet/dry paper from Harbor Freight. I only sand down flashing, molding or spruce marks off my bare plastic. The model should have no issue holding paint to the surface, especially if you have a nice primer coat, so no sanding needed. I only wet sand on primers to smooth any imperfections. I tend to cross my fingers and hope, with a nice laying primer coat, that finish and clears will spray on evenly how they are supposed to. However, keeping some 2000+ grit stuff around in case there are some anomalies that need wet sanding should keep you out of trouble there.

I aim to make something that can be considered art, but concede this is just some plastic at the end of the day.
See you out here,
-Art.

 

[dogfish7]

Dupli-Color Sandable Primers work best for me.

 

[stevethefish]

Some Western model kit makers do not remove the mold release agent before packaging. Kits under the Round 2 umbrella (AMT, MPC, etc) can be downright greasy at times. I have Star Trek kits that are pretty greasy. Moebius is the same in my experience. I built the B9 robot from Lost in Space and some areas in the cracks wouldn't hold paint and I didn't realize why at the time. At that time, I had mostly built Japanese model kits, so I was spoiled.

I prime everything (save for clear parts, of course). Use an actual primer and not just some other paint. Primers are there for adhesion. Go with a lacquer primer because lacquer is the sturdiest, like the Tamiya primer you have. I dunno where you live, but I imagine Mr. Surfacer in rattle cans is hard to come by.

I don't bother wet sanding a primed surface, but for painted surfaces, it is best to wet sand. Only sand imperfections.

When it comes to cars and you are going for a gloss finish, don't worry if you have to wet sand even the final gloss coat. You can bring the shine back through using polishing compounds and later modeling wax if necessary.

I've heard that Testors Glosscote and Dullcote can turn yellow after a few years. I've had two people tell me this from their own experiences. One guy had a white Macross Valkyrie turn yellow and the other had a Millennium Falcon turn beige. YMMV, but I'd recommend Tamiya's clears.

I cannot vouch for Krylon or other rattle can products. It's not that I'm a snob, but I just didn't really build serious modeling experience until after I moved to Japan. The safest bet is to use paints that are made for the hobby instead of actual cars, fishing lours, etc.

I will say that it's best to avoid painting entire surfaces with enamels. Those are best used for detailing and such. Modelers here are baffled at how people in North America use enamels exclusively for their models. How do they use an enamel wash over a kit with an enamel paint job and an enamel clear coat? Beats me.