Help with sanding issues

[18degrees]

Hey y'all... so for those of you that never noticed on my builds, i always remove the molded in hood pins, roof camera, etc from my builds. The issue i have been having is that my sanding technique/routine has been leaving scratches in the plastic, mostly on the hood.

My old sanding routine was 400, 1000, 1500 then 3000 grit. I have gone to using sanding sticks and last night i used 240 to remove the pins/camera/rocker molded exhaust (Gen 6 Fusion glue kit) and then used 800, 1000, 2000 and then 3000. This left scratches on the hood that are evident after 2 coats of primer and 3 coats of paint (Tamiya white primer and Blue paint). Not sure about the trunk pins, roof camera and exhaust... i just did the first coat of primer.

So what is the issue? Starting off too coarse, not using the finer ones long enough... i have no idea.

Suggestions and your techniques are requested and appreciated at this point.

[jh63fan]

The only thing that comes to mind is the Tamiya primer. It is real fine, not really a scratch filling primer. Lately I have been using Upol sandable primer I get at AutoZone. It fills the scratches I create well. I final sand with 600 or 800 and no finer before painting without any problems. For your lighter colors you can coat with the white primer before color coating.

[18degrees]

The only thing that comes to mind is the Tamiya primer. It is real fine, not really a scratch filling primer. Lately I have been using Upol sandable primer I get at AutoZone. It fills the scratches I create well. I final sand with 600 or 800 and no finer before painting without any problems. For your lighter colors you can coat with the white primer before color coating.

The white primer i am using is the "fine" variety. Just what i grabbed at the local shop. I have some regular grey and some fine grey too. I have to get some more white primer so maybe i will try and grab some "normal" Tamiya primer that isn't fine.

The body (roof camera, trunk pins and molded exhaust exit) seems to have turned out ok, at least in the primed stage.

[Brian Conn]

...I have been using Mr Surfacer products with great success on everything from styrene and resin to 3-D printed pieces.

[sid charles]

#240 to #800 is kind of a jump.

obviously the finer grits are not the ones causing the scratches.

the primers are shrinking down to cover the details like we want them to do.

i have found numbers on sandpaper vary from brand to brand.

[18degrees]

#240 to #800 is kind of a jump.

obviously the finer grits are not the ones causing the scratches.

Makes sense. I started with the 240 so it would take more material off faster. I suppose i could start with 400 or 600 and then use the others i listed.

Next time

[Volzfan59]

Depending on the thickness of the mold line, I start with 600, then 800, 1000 sandpaper. I have 1500 and 2000 if needed. Also have 400 if needed, but that's pretty rare. I have some Duplicolor primer that fills in scratches, but to be honest I rarely have them. Also have sanding sticks in various grits.