compound at the beginning?

[youpey]

does anyone here compound the bare plastic before primer? i used to own this stuff called key and clean, which looks like it is just compound and a cloth scrub cloth to get the plastic perfect.

i can't find key and clean in the USA, so i was thinking of just using the tamiya course polish. has anyone else tried using compound on the bare plastic?

[Snake45]

No. Sounds like a waste of time. If anything, you'd want the plastic just a little rough before primer, not polished. #600 grit sandpaper is about perfect. A Scotchbrite pad (finest grit) works well, too. 

That said, I usually don't do any prep to my bodies before priming/painting, except of course any necessary bodywork such as mold line removal (and panel line deepening). 

[gman]

I used to finish sand and polish model car bodies before paint, years ago. After having primer and top coat come off in sheets while handling a couple of bodies during assembly and polishing, I now leave some "tooth" on the plastic. Doing final sanding of plastic and body work with fine sandpaper or Flexi Files, but not going up to the finest grits leaves something for the following primer/paint coats to adhere to, and the primer and paint coats are usually enough to fill those fine scratches on the plastic if done correctly.

It may take some experimentation to figure out how fine is too fine for final finishing under primer, but if sanding scratches don't show through your primer after it is cured and fully gassed out, and your following colour coats aren't hot enough to saturate that primer with solvent, you're usually good.

[Chariots of Fire]

I would not put anything on the plastic in the way of polish or compound.   It might interfere with adhesion of the paint.  Do the polishing on the paint after it has cured.

[stitchdup]

I would use an abrasive household cleaner instead of polish

[espo]

The closest to polishing would be an 800 to 1000 grit sanding pad. this will help show any unseen seems or high spots after priming. Like any paint job it's all in the prep of the body before the color coats or even clear. 

[Dave G.]

Mostly I just prime, except to fix the obvious things first of course. I used to scuff with pads 400-600ish grit but not since the multi day stripping I experienced when I decided to change colors mid build. Sheesh, Stynylrez primer sticks well without scuffing, never had anything lift.

[Erik Smith]

Soap and Comet. 
 

 

[Deuces ll]

First I dip the body and hood in a clean tub of Super Clean to disolve the mold release oils.. Do what final prep the body might need likes mold lines and what not... Then use ultra fine scotch brite (the grey stuff) on the body and hood just to remove the shine in the plastic and last but not least, wash those parts with warm water and dish soap... Let dry for a day and then paint....

Edited February 17, 2021 by Deuces ll

[youpey]

7 hours ago, Deuces ll said:

First I dip the body and hood in a clean tub of Super Clean to disolve the mold release oils.. Do what final prep the body might need likes mold lines and what not... Then use ultra fine scotch brite (the grey stuff) on the body and hood just to remove the shine in the plastic and last but not least, wash those parts with warm water and dish soap... Let dry for a day and then paint....

Mine used to be almost the same. I didnt do the initial dip. I would sand the lines and then use the key and clean, which looks like just the scotch brite pad and compound and then i would wash with dish soap and let it dry overnight. 

I Ordered a scotch brite pad in ultra fine and it should arrive today. i will use that going forward. i had tried using a fine grit sand paper but that fidnt always go well. I needed to be extra careful. 

[Deuces ll]

I have a whole box of the ultra fine pads that I ordered through work.... I have enough to last me a lifetime....

Think I only paid 13 bucks for the box at the time....

[Mike 1017]

I use the Don (Youst ?) method. I use one of those polishing kits that starts with 2400 grit through 12,000 grit.  Just use hot water and soap. Then primer the car. It should be very smooth. 

Good luck

Mike

[youpey]

 i started using tamiya course compound with the 3m ultra fine hand pad and it is making the surface exactly like the key and clean. Roughed up for primer, but does not appear scratched. im going to try to find a car compound so i can get a better deal vs the price of tamiya compound

 

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