The proper amount of sanding

I just give them a good scuff with a gray scotchbrite pad. Just enough to get rid of the shiny surface. Since I work at a body shop, I have easy access to them.  Can get them at an auto parts store or auto paint supply store.  Not real expensive either.

They don't remove any detail, and leave a nice dull finish with some bite for primer.  Will also do a light scuff with them prior to color coat to give some bite to the primer.  Since I generally do aircraft and ships in flat paints, I don't need to worry about a glossy base like you need for finishes like alclad, but after primer and before a gloss coat should be the same. Though I'll let others chime in with their preferences for gloss stuff.

Thanks for the info Goldhammer.  I'll have to give them a rip. 

T e d

I hope you get a lot of responses 'cause there are many good builders here who offer many good tips. A lot of what I know I learned here; giving credit where it's due.

Sticking to surface prep alone, I believe that washing and rinsing all the sprues is a good idea. From there surface treatment is about what you have to work with. Some kits have nice shiny plastic while others will be more coarse. My favorite sanding product is 3M's line of foam backed pads, about 5" x 5" square, available at automotive paint stores. For the shiny plastic, the Microfine grade used wet is all it takes (I use the pads until they're bald). Superfine grade will buff down coarse surfaces in short order, again used wet.

Surface prep also has to do with the type of primer and paint products you use. Lacquers are very "hot" and bond to smooth plastic, enamels less so. Acrylics need a surface with more "tooth". It's always a good idea to try differant techniques on scrap plastic before doing it to the project you value...but I can't say I've always done that.

Maybe something I said will help; happy modelling!

mike

goldhammer

I just give them a good scuff with a gray scotchbrite pad. Just enough to get rid of the shiny surface. Since I work at a body shop, I have easy access to them.  Can get them at an auto parts store or auto paint supply store.  Not real expensive either.

They don't remove any detail, and leave a nice dull finish with some bite for primer.  Will also do a light scuff with them prior to color coat to give some bite to the primer.  Since I generally do aircraft and ships in flat paints, I don't need to worry about a glossy base like you need for finishes like alclad, but after primer and before a gloss coat should be the same. Though I'll let others chime in with their preferences for gloss stuff.

 

I never really considered sanding parts prior to priming (short of some nasty plastic surface imperfection). You do make a compelling argument. Hmmmmm......

I'll add that my go to primer is MM's 2981 gray laquer primer in the rattle can.

With the exception of Alclad, all my paints are acrylic.

Greg

 

 

goldhammer

I just give them a good scuff with a gray scotchbrite pad. Just enough to get rid of the shiny surface. Since I work at a body shop, I have easy access to them.  Can get them at an auto parts store or auto paint supply store.  Not real expensive either.

They don't remove any detail, and leave a nice dull finish with some bite for primer.  Will also do a light scuff with them prior to color coat to give some bite to the primer.  Since I generally do aircraft and ships in flat paints, I don't need to worry about a glossy base like you need for finishes like alclad, but after primer and before a gloss coat should be the same. Though I'll let others chime in with their preferences for gloss stuff.

 

 

 

 

I never really considered sanding parts prior to priming (short of some nasty plastic surface imperfection). You do make a compelling argument. Hmmmmm......

 

I'm with Greg.  I never sand raw plastic.  I sand the primer to take out any dust particles or other imperfections.  Throughout the painting process I sand to keep smooth surface.  I can see when surface is good, and ready for next coat.

I certainly do sand seams that have been filled, and primer helps me to see if the surface is ready for painting.

I have to say that I never sanded the surface or washed my plastic parts to apply primer,the primer has always adhered with no problem as well as the paint coat.

Well these are all very helpful and interesting responses.  

I think my builds will be progressing much faster now.  

Thanks everyone!  

T e d

My two centavos..

1. I do wash the plastic, usually before paint. Not only to remove potential mold release agents, but more so to remove any oils I left behind from my handling. Nacho chips--potato chips--chocolate bars--all the good stuff I may have been stuffing my face with adds to the problem too. 

2. I don't sand raw plastic unless there are imperfections. For better adhesion, maybe I should. Generally speaking--I have not had problems by not sanding. Will consider this more though.

3. Taking this a little further than the plastic question; I do wet sand the primer coat. Mostly--it knocks the grain down for subsequent paint layers. It's cumulative. So, each layer adds more grain to the finish. 

I am out of centavos. Now what.

Tojo72

I have to say that I never sanded the surface or washed my plastic parts to apply primer,the primer has always adhered with no problem as well as the paint coat.

 

Only sanding i do is seams and any rough patches and i have never washed a kit or parts, be it plastic or resin.

Bish

 

 

Tojo72

I have to say that I never sanded the surface or washed my plastic parts to apply primer,the primer has always adhered with no problem as well as the paint coat.

 

 

 

 

Only sanding i do is seams and any rough patches and i have never washed a kit or parts, be it plastic or resin.

 

#2

Another vote for no sanding.  I have never found it necessary, as the primer always adheres to bare plastic very well.  I don't wash it, either, the only exception being resin parts.

how about the Stainless Steel Model File Stick from http://www.galaxy-model.com?  Do they last forever?

I don’t sand before priming. Besides, I don’t see the need to. A waste of time actually...

I think those sticks are sticks only , you have to stick on the sandpaper .

steve5

I think those sticks are sticks only , you have to stick on the sandpaper .

 

Yup. They're not like a nail file per say. Save your money on those. Buy the cheap sandstick in the beauty dept at Walmart. However, the finer grits you have to find at Hobby Lobby or online.