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PostPosted: Mon Aug 29, 2011 8:44 am 
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Koa
Koa
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Joined: Sat Mar 07, 2009 7:56 am
Posts: 1825
Location: Grover NC
First name: Woodrow
Last Name: Brackett
City: Grover
State: NC
Zip/Postal Code: 28073
Country: USA
Focus: Build
It takes this Varnish up to 30 days to fully harden, but all of the shrinkage is over quickly. I like to start buffing after 5 days or so. It's easier to sand as long as you don't use too much pressure, and keep the surface clean while sanding. If you done a good job applying the finish it will be shiney, and fairly smooth.
Attachment:
Before buffing.jpg


I start by sanding with a RO sander and 600 grit. Use fresh paper, keep it clean, and no pressure. Let the paper do the work.
Attachment:
Buffing first step.jpg


I do the sides mostly by hand. When I use a powered sander on curved surfaces I get into trouble.
Attachment:
Doing sides by hand.jpg


After sanding with 600 grit the entire body should be smooth and flat. If you've got areas that you can't get flat you may need more coats. Be consistant with your sanding. Don't spend more time sanding in one area. Again, if you can't get a smooth, level surface you need more coats of finish.
Attachment:
After 600 grit.jpg


Once the entire body is smooth and flat, with 600 grit scratches it's time to get rid of the scratches. Buffing is mostly about scratching. You just replace scratch marks with finer/smaller marks until they aren't visible. Next step is to sand with 800 grit. If you skip grits you'll never get a glossy surface. I do the 800 grit sanding by hand. Finer grits will build more heat. I get into trouble using really fine grits with power tools. I cut paper to fit my sanding block. You can use soapy water for a lubricant, but as long as you don't use too much pressure it isn't necessary.
Attachment:
Cutting sandpaper.jpg


It doesn't take long. Again, use fresh paper, keep the paper and surface clean, and use little or no pressure. One of the biggest mistakes I see if people using alot of pressure when sanding. This balls up the finish and creates deep scratched. Let the paper do the work. You can see the surface change from the dull 600 grit surface to a slightly less dull surface as you sand.
Attachment:
After 800 Grit.jpg


Next step is 1200 grit. Same as 800, and doesn't take long. You can see the surface get less dull as you sand. Again, no pressure, fresh paper, clean paper and surface.
Attachment:
Final 1200 grit sanding.jpg


The process from 600 grit through 1200 grit takes me ~30 minutes. I do my final buffing with a pedastal buffer (next post) but you can get good results buffing by hand. To continue buffing by hand go through 1500 grit, the 2000 grits the sand was as the 800-1200. Then buff with a soft clean cotton cloth and Stew Mac polishing compounds, first medium, then fine. Stew Mac preservation polish is great for final touch ups.
This guitar was finished with Varnish, and buffed by hand, before I got my pedastal buffer.
Attachment:
Buffed by hand.jpg


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PostPosted: Mon Aug 29, 2011 9:09 am 
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Koa
Koa
User avatar

Joined: Sat Mar 07, 2009 7:56 am
Posts: 1825
Location: Grover NC
First name: Woodrow
Last Name: Brackett
City: Grover
State: NC
Zip/Postal Code: 28073
Country: USA
Focus: Build
As stated earlier I now buff with a pedastal buffer. I use a Caswell buffer, 1100 RPM with 12" canton cotton weave wheels. Varnish requires less heat than lacquer to buff, so be sure to use plenty of compound, and take your time. Here's a short video on the basics of using a power buffer.
http://www.brackettinstruments.com/Buffing%20basics.wmv

I use menzerna medium, followed by fine. Use a separate wheel for each compound. I warm the wheel first with a block of wood.
Attachment:
warming buffing wheel.jpg


Charge the wheel by holding the compound against it. Keep it charged. I suppose it's easy to use too much compound, but too much is better than not enough.
Attachment:
Charging buffing wheel.jpg


As shown in the video keep the body moving, and don't let any edges catch on the buffer. Just like sanding, pressure is pretty much your enemy. Too much pressure = too much heat. Let the compound and wheel do the work. When buffing the sides be careful to keep the body below the center of the wheel. Don't let the wheel get to the top edge of the body. Do the bottom half, turn the body around, and do the other half.
Attachment:
buffing sides.jpg


After the medium compound it has a decent shine, but not as good as we're looking for.
Attachment:
After medium compound.jpg


The process is the same with the fine compound. Warm the wheel, then charge it, and keep it charged. Fine compound builds a little more heat so be careful.
Attachment:
buffing with fine compound.jpg


After using the fine compound it's glossy.
Attachment:
After fine compound.jpg


After assembly you can use Stew Mac fine polishing compound on any area you mess up during assembly. Final clean up with Stew Mac preservation polish leaves a glossy, glassy surface. I can't find a picture of this guitar assembled (opps) but this one was finish with exactly the same materials and procedures.
Attachment:
Varnish finish, power buffed.jpg


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_________________
I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/



These users thanked the author woody b for the post: Hibdon Hardwood (Tue May 13, 2014 1:44 pm)
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