Final sanding/buffing with nitro... how did you do yours?

[Liam]

I'm doing an aerosol re-finish on a MIM j-bass body, and am currently waiting for last coats of  clear to harden/shrink.

When I started, I figured it would be just as easy as many of the autobody components I've refinished and wet-sanded/buffed to a decent luster. Basically, I just sanded it with 1200-1500 and rubbed it with fine 3M compound to get a good gloss.

I look at this piece in it's state, and I just cannot picture it being glossy. lol!

Think I'll stick with tung oil finishes from here on.

Anyway, I plan on starting the process this weekend, any pointers would be greatly appreciated!

Thanks!

 

[-CB-]

You need to remember that THICK nitro finishes take forever, and then forever again to dry.... even then they shrink.

THIN is better with nitro.

Having said that, you can wet sand with 600 grit using kerosene as a medium.  Kerosene (or lamp oil) seems to work better than water.  You'll want to level the finish with a block and 600 grit paper - using very light pressure (wet), then using finger pressure continue to lightly sand out remaining texture in the finish.

Once you have the body looking uniformly dull - and level - then you need to wash it in naphtha.  Then you can buff it out.  I use white compounding (lacquer safe) made for cars.  Then wax it with (lacquer safe) car polish... and you'll have one shiny geetar.

You may notice later... I missed a spot or this needs some help... its ok, just wet sand the area lightly and rebuff. 

Thats all!~

 

[GUNSNGUITARS]

One thing I found out was the importance of sanding between every 3 or 4 coats to level sand when using Nitro, which a urethane finish is a little more forgiving.  My last project I sprayed several builiding coats, waited 2 weeks, wet sanded, and found out I should have been knocking down the orange peel as I went.  I wound up having a sand through and had to reshoot a few more coats.  Also I picked up on this board the importance of shooting a flow coat your last 1 or 2 coats, which is a 50/50 mix of Nitro and Thinner.  I used Behlen Instrument Grade Nitro. Some manufacturers may have different mixes for their product. Being that your using aerosel cans, you will have to sand more than normal.  One thing you'll find out with Nitro is that there are alot of different methods and every one will work. Learn as you go. Good luck

 

[dmraco]

One thing I found out was the importance of sanding between every 3 or 4 coats to level sand when using Nitro, which a urethane finish is a little more forgiving.  My last project I sprayed several builiding coats, waited 2 weeks, wet sanded, and found out I should have been knocking down the orange peel as I went.  I wound up having a sand through and had to reshoot a few more coats.  Also I picked up on this board the importance of shooting a flow coat your last 1 or 2 coats, which is a 50/50 mix of Nitro and Thinner.  I used Behlen Instrument Grade Nitro. Some manufacturers may have different mixes for their product. Being that your using aerosel cans, you will have to sand more than normal.  One thing you'll find out with Nitro is that there are alot of different methods and every one will work. Learn as you go. Good luck

OK...you recommend sanding every 3-4 coat.  My question is how long to dry BEFORE sanding and what grit paper?  Also..I guess their are no adhesion problems when letting it dry completely and then re-shooting.\

Thanks.

 

[Tonar8352]

My question is how long to dry BEFORE sanding and what grit paper?

The best way to tell when it is ready to between coat sand is when the lacquer powders as it is sanded. Dry time will be determined by how much thinner and what kind of thinner, and how heavy you shot the finish on.  It will also be different with different lacquers. If it is not ready it will roll up in little balls on the paper.  

Most lacquers will powder after 1-hour dry time if you don’t have too much on.  I like to shoot 4 heavily thinned coats about an hour apart then let it set overnight to shrink before I level sand.   It was recently recommended that I do my between coat sanding with the grain which old school painters never worried about including me.  I gave it a try and I found my sanding scratches re-melted better than if I had done it the old way of going every direction.  I always use a wood sanding block wrapped with a 3M sanding sponge and my paper over that.  I stay away from edges with the regular paper and touch them real lightly with a worn out 3M 320 Sanding Sponge to dull the finish up.  For my abrasive I have found the Norton 320 Champagne to work the best but the 3M Sand Blaster Gold is good also.

 

[GUNSNGUITARS]

I'm currently spraying that Flake finish we talked about before. I'm to the clear coats. I shot my last coat around 6 last night. I just went to level sand this morning at 7, and I almost think I'm going to give it another 6-12 hours. It seems like it isn't dried completely, almost semi-tacky if that makes sense. I gave it 3 un-thinned clears fairly heavy because of the texture of the flakes/metallics.  By the way, the finish turned out awesome.  I wound up spraying Cobalt Blue MIcro Flakes over a Black Base. I'll post pictures later tonight if I get time with the details on what I did.

Also alot of you guys thin your clear coats. I do this but not til the last 2 coats. Am I creating more level sanding than what I need to??I use the real un-thinned "Crap" to build the coats. I use Behlen Instrument Grade which I think already has all the additives in it.  I was thinking about trying McFadden Nitro next spring. Anyone ever use this stuff??

 

[dmraco]

I'm currently spraying that Flake finish we talked about before. I'm to the clear coats. I shot my last coat around 6 last night. I just went to level sand this morning at 7, and I almost think I'm going to give it another 6-12 hours. It seems like it isn't dried completely, almost semi-tacky if that makes sense. I gave it 3 un-thinned clears fairly heavy because of the texture of the flakes/metallics.  By the way, the finish turned out awesome.  I wound up spraying Cobalt Blue MIcro Flakes over a Black Base. I'll post pictures later tonight if I get time with the details on what I did.

Also alot of you guys thin your clear coats. I do this but not til the last 2 coats. Am I creating more level sanding than what I need to??I use the real un-thinned "Crap" to build the coats. I use Behlen Instrument Grade which I think already has all the additives in it.  I was thinking about trying McFadden Nitro next spring. Anyone ever use this stuff??

Gunsandguitars...I am glad to hear it turned out well.  WIth Automotive clears, I would let it sit a few days...2-3 before sanding.  I usually wait 1 week.  That clear will take about a month to completely harden so if you wait longer that that it will be a real pain.  also...you can polish but DO NOT WAX it for at least a month...it screws with the cure.

Depending on the finish...I always wet sanded with 1000...then 1500...then 2000, then a good grade polishing compound...  Looking forward o the pics!!

 

[Liam]

Well I ended up sanding through near the bridge. 

I guess my motto still stands... nothing good ever comes out of a can. Whether it's food, beer and especially paint.

 

[dmraco]

I have been lightly sanding every 6 coats.  It is really looking nice and shinny.  At this point I am about 1/2 way there.  It is continues like this...I will only need 2000 grit and compound at the end.

what grit did you want thru with and did you use any type of block??  Are you usingthe STEW-MAC nitro??