Prepping for paint

[Rockford]

I'm doing this AMT Trailmobile van and in want to spray it using rattle cans. My issue is that the usual method of using 800 grit wet and dry paper will seriously damage the mass of rivet detail on the skin of the van. How do I establish a key for paint? I'm thinking of a toothbrush and some sort of water-based abrasive paste but can't think what. 

What do the aero builders use? 

Edited March 30, 2021 by Rockford
Photo wouldn't attach

[youpey]

I found that using tamiya course compound applied using https://www.amazon.com/gp/aw/d/B00HSCNVM2?psc=1&ref=ppx_pop_mob_b_asin_title

 

Gives the perfect amount of rough surface without having scratching issues or losing detail issues.

 

Basically I apply the compound with the pad, and let it dry for a few minutes and then wash it with dish soap and water with the bath tub faucet. The regular sink doesn't have enough water pressure. i suppose I could wipe it off with a rag but this is very fast clean up

 

I have not tried other compounds to know if they will work.

Edited March 30, 2021 by youpey

[Mark]

I use mild kitchen cleanser and an extremely soft old toothbrush on areas I don't need/want to sand.  Just make sure all of it is cleaned off prior to any painting operation. 

Mild rubbing compound would work too, again be sure to get all of it cleaned off.

[Casey]

45 minutes ago, Mark said:

I use mild kitchen cleanser and an extremely soft old toothbrush on areas I don't need/want to sand. 

I'll second this. Bon Ami or Bar Keepers Friend cleansers are both good choices, neither of which are too harsh/coarse. Great for getting into all those nooks and crannies around engines, suspension parts, etc.

Edited March 30, 2021 by Casey

[Plowboy]

Comet also works well.

[Snake45]

3 hours ago, Rockford said:

What do the aero builders use? 

Most model airplanes haven't had rivets like that in 50 years, and when we see them on old kits today, we usually sand them off. 

[NOBLNG]

What Roger said.? With a bit of water, and rinse well when done.

Edited March 30, 2021 by NOBLNG

[peteski]

Foe another view point, I have built many polystyrene model kits and I have *NEVER* done any abrasive prep to the entire body. Yes, i scrape and sand the flash and mold parting lines, and any spots on the surfaces that are not smooth, but I never do the entire body.  I use "stinky" paints and they seem to "grab" the bare plastic surface just fine.  But I can't  comment about the now-popular water-based paints since I don't use them.  I often don't use primer either, if the plastic color is neutral enough (or similar to the paint color), I shoot the final color directly on plastic.

[Snake45]

54 minutes ago, peteski said:

Foe another view point, I have built many polystyrene model kits and I have *NEVER* done any abrasive prep to the entire body. Yes, i scrape and sand the flash and mold parting lines, and any spots on the surfaces that are not smooth, but I never do the entire body.  I use "stinky" paints and they seem to "grab" the bare plastic surface just fine.  But I can't  comment about the now-popular water-based paints since I don't use them.  I often don't use primer either, if the plastic color is neutral enough (or similar to the paint color), I shoot the final color directly on plastic.

Same here. I'll sometimes wipe a model down with rubbing alcohol to de-grease it, but I don't routinely "abrasive prep" plastic that I haven't otherwise had to work by sanding and so forth. 

[Doug 1061]

Maybe you could try scotch-bright scuffing pads like they use on 1:1 cars.  It should knock the nubs off the rivets without grinding them away.   Just a thought.

[Dave G.]

000 or 0000 steel wool, just rinse it good after so no steel fibers are left on the model.

[Rick L]

If the van is styrene, you can use a lacquer based primer that will etch into the plastic without sanding. If you are proficient at painting with cans, put a steady stream of primer on. It may take a little practice. You want it wet but not too wet obviously so as not to flood out the details. Any dust spots can be swiped off with a fine Scotch-brite pad. Then you can use any based type paint you want over that.

if the van is not styrene, any one of the cleaning techniques should work fine.

 

 

 

 

Edited March 31, 2021 by Rick L

[Rockford]

Gents

Thank you one and all for your input and suggestions. 

I use automotive rattle cans and so always use a primer out of fear of a reaction because the solvents are too "hot".

I would also be terrified of the paint peeling with the use of masking tape to apply the primer without some form of rubbing down.  

So, taking all your suggestions into account I shall use the wire wool method, then primer and topcoat.  

Thanks again everyone,  you guys are so very helpful.