What grit to use?

[hoggworks]

Hey all,

I've printed some Star Trek badges I modelled, in resin, and they're mostly very good, but I need to tidy up the surface a little before hitting them with primer and chrome.

I can't really feel the lines under my finger, but what grit would you briefly hit this with to get it a little smoother? I'm more concerned than I'd normally be on account of the chrome paint.

Thanks!

 

[Astyanax]

If my resin prints are already looking pretty good, I will wet sand them with 600 grit. Then, I'd take a close look at them after priming and hit them again with the 600 wet. If I need to remove more material, I come down to 400, but not lower than that.

I almost never use lower than 400 grit sandpaper on my resin prints.

 

[Antsnest]

If you're going for chrome you need a flawless finish. I'd agree with Astyanax above but then I'd hit it with some yellow filler primer and wet sand that back with 800-1200 for a glass-flat surface.

 

[yaris]

I use True Grit........

 

[hoggworks]

If my resin prints are already looking pretty good, I will wet sand them with 600 grit. Then, I'd take a close look at them after priming and hit them again with the 600 wet. If I need to remove more material, I come down to 400, but not lower than that.

I almost never use lower than 400 grit sandpaper on my resin prints.

Thanks!

 

[hoggworks]

If you're going for chrome you need a flawless finish. I'd agree with Astyanax above but then I'd hit it with some yellow filler primer and wet sand that back with 800-1200 for a glass-flat surface.

Thanks!

I don't think I've wet sanded before, that's just water and not a special liquid?

 

[Jkirkon]

Just water.

 

[PHArchivist]

Thanks!

I don't think I've wet sanded before, that's just water and not a special liquid?

Yes - just be sure of course you have the proper sand paper (for wet-sanding).

For me it is a very satisfying experience / technique.

And I agree that for a metallic finish, you need to go at least 1000 - 1200, if not higher (like 1500 - 2000).

Check an auto parts store if you have trouble finding the paper (or of course on-line).

 

[hoggworks]

Yes - just be sure of course you have the proper sand paper (for wet-sanding).

For me it is a very satisfying experience / technique.

And I agree that for a metallic finish, you need to go at least 1000 - 1200, if not higher (like 1500 - 2000).

Check an auto parts store if you have trouble finding the paper (or of course on-line).

Thanks!

 

[Astyanax]

Question for Antsnest and PHArchivist : Is it necessary to go to that high of a grit if you're going to hit it with black gloss prior to chroming? I always figured the gloss will be as shiny as it is regardless of how smooth the underlayer is, so long as it's not terribly rough. And slightly rough helps the gloss stick better, doesn't it?

Thanks!

 

[Antsnest]

A great finish always requires great surface prep. You won't get a good chrome without a good gloss basecoat and you won't get a good gloss basecoat without a good surface beneath it.

Gloss appears glossy because at a very microscopic level the surface of the paint is flat and reflects light back at you. A matt paint appears matt because it is relatively rough and scatters the light in all directions instead.

So for gloss to really work, it has to start off on a very very flat surface. Any imperfections will immediately be visible and ruin the overall gloss effect. These imperfections will then be visible in the chrome coat over the top.

 

[PHArchivist]

Question for Antsnest and PHArchivist : Is it necessary to go to that high of a grit if you're going to hit it with black gloss prior to chroming? I always figured the gloss will be as shiny as it is regardless of how smooth the underlayer is, so long as it's not terribly rough. And slightly rough helps the gloss stick better, doesn't it?

Thanks!

I'd say, it is necessary...

Gloss black, primers, and silvers are WONDERFUL at showing up the finest of scratches and sanding marks.

I'd go at least 1500 - 2000

And be sure to lay down your black with no orange peel or other imperfections...

 

[Jkirkon]

I'd say, it is necessary...

Gloss black, primers, and silvers are WONDER at showing up the finest of scratches and sanding marks.

I'd go at least 1500 - 2000

And be sure to lay down your black with no orange peel or other imperfections...

This.

It is 1000% about surface preparation.

 

[pengbuzz]

Thanks!

THis might be of assistance to you:

Flex-I-File Fine Pro Sanding Film Sheet 5 pack (4x4) Hobby and Model Sanding Hand Tool #202

This is the Flex-I-File Fine Pro Sanding Film Sheet 5 pack hobby and model sanding hand tool.

www.hobbylinc.com

 

[swgeek]

I would pick up some sanding sponges, you can get them at your local hobby shop. I'd start at 400 and finish with 600, then prime, and sand with 800, hit it with whatever black you're going to use and you should be good. As for wet sanding, real wet sanding (which I rarely do) should have running water on your part at all times. So sand under the faucet kind of thing, but if you're just going to use a bowl of water, add a drop of dish soap, it will help move the dust particles out of the way.