Wet Sanding

[sandtrooper[501st]]

Hello everyone, 

 

My current project is a jimmiroquai FO snowtrooper kit that will require the armor to be painted. 

 

Other builds have mentioned wet sanding for primer and the paint coats.  What technique is used for wet sanding in the sense do you lightly sand or really lay into it?  Also does the direction of the sanding strokes matter?

 

Currently the armor has been sprayed with gray primer to find pin holes and bubbles that were filled with putty.  The parts have been wet sanded with 400 grit sandpaper with the result being a lot of the primer is gone.  Next will be multiple coats of white primer, sanding, then the final paint.

 

Any help/advice would be appreciated.  Thank you.

[wook1138[TK]]

Light sanding should do it - "let the sandpaper do the work", as they say.  I start with coarser paper on my first coat or two of primer (I use filler primer) - like 100 or 150 grit, to do your heavy lifting if needed.  Then work up to about 300.  By my second or third coat, I'm sanding up to at least 600 grit paper.  Depending on the finish I'm going for, I'll sand and polish up to 2000 or 3000 grit paper/polishing sheets.  Most of my experience has been sanding 3D prints - I usually stop at 600 grit for blasters.  ABS sanding I will go to much finer grits and eventually Novus polish and cleaner.  Not much help when it comes to fiberglass specifically. 

 

I always try to use circular patterns when sanding - whenever I can.  You don't want to gouge out putty or filler that is along seams or, in my case, print lines - so sanding perpendicular to these sorts of features is a good idea. 

 

The best advice I can give is do lots of sanding and polishing with the primer layers.  Take your time.

 

By the way, FO snowy - Nice!  That is awesome armor!

[repentance3232[TK]]

I know that you don't want to sand in a small circle or you will dig a dent into the armor as well, I recommend 2 inch diameter if possible

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[sandtrooper[501st]]

3 hours ago, wook1138 said:

Light sanding should do it - "let the sandpaper do the work", as they say.  I start with coarser paper on my first coat or two of primer (I use filler primer) - like 100 or 150 grit, to do your heavy lifting if needed.  Then work up to about 300.  By my second or third coat, I'm sanding up to at least 600 grit paper.  Depending on the finish I'm going for, I'll sand and polish up to 2000 or 3000 grit paper/polishing sheets.  Most of my experience has been sanding 3D prints - I usually stop at 600 grit for blasters.  ABS sanding I will go to much finer grits and eventually Novus polish and cleaner.  Not much help when it comes to fiberglass specifically. 

 

I always try to use circular patterns when sanding - whenever I can.  You don't want to gouge out putty or filler that is along seams or, in my case, print lines - so sanding perpendicular to these sorts of features is a good idea. 

 

The best advice I can give is do lots of sanding and polishing with the primer layers.  Take your time.

 

By the way, FO snowy - Nice!  That is awesome armor!

 

Thank you for the response.  How many layers of primer do you usually shoot?  I take it the Novus is used before adding the paint or is it after?  Thanks!

[wook1138[TK]]

1 minute ago, sandtrooper said:

 

Thank you for the response.  How many layers of primer do you usually shoot?  I take it the Novus is used before adding the paint or is it after?  Thanks!

Oh, the novus is for the ABS when not painting.  This was more for smoothing out/finishing ABS paste.  Never tried it on paint.  Sorry for the confusion.

 

Layers of primer depends on how rough the surface is and how smooth it needs to be.  I've never done less than 3 coats of filler primer.  I go until the surface (filler primer) feels smooth to the touch - I usually finish up with at least a 600 grit polish and move on to painting . 

 

Are you planning on a clear coat to finish?  A quality clear coat might save you some polishing/sanding and also protect the armor.  I have no experience with that (at least not on a full set of armor).  I've read of people taking their armor to automotive shops to have it clear coated - although, I'm sure that doesn't happen cheaply.  Hopefully someone with more experience with that will chime in.

[sandtrooper[501st]]

I'm following Jon Watson's building method since he originated the whole costume from scratch.    A gray filler primer has been used to find the problem areas.  Then switching to white filler primer for at least three coats and wet sanding.  The paint is an automotive type with clear coat mixed in.

[sharkbait[TK]]

When I get to wet sanding, I'm already at the point where I'm using a super-fine sandpaper.  I take a seat and put a bucket of water next to me and rinse the sandpaper off fairly regularly, probably less of an issue with heavier grit as it won't get clogged as fast and loose its effectiveness.  Let the sandpaper do the work, that's it's job, and I personally like longer strokes, but I think it depends on what you're working on.  When I sanded down the edges of armor so it wouldn't poke, I used short, fast strokes, when I sanded down the mold-line on my TIE helmet mohawk, I used longer strokes.  

 

Novus, Can-Do, and Plexus (all similar, but Can-Do and Plexus are heavier on polish and less on fill in, and only one step) are for polishing and buffing out fine scratches, so you'll use them later on down the road for upkeep and repairs to keep up that awesome paint job you've done.  Novus, to my knowledge, will buff out slightly deeper scratches than Can-Do and Plexus, but I've not used it, while I have used the others, so I'm not 100% on that.