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PostPosted: Thu Mar 24, 2011 11:16 pm 
I just finished spraying a guitar with EM6000 and thought I would share my procedures.

I am not going to cover my pore filling process, but for this guitar, I used Zpoxy. I can't emphasize enough that preparation is essential to a good finish. The surface of this guitar was very smooth prior to even beginning. I wanted to keep a thin film of Zpoxy on the surface, so once I had the guitar pore filled and leveled, I swabbed it with Zpoxy diluted with DA (denatured alcohol). Because Zpoxy has a bit of an amber tint, this evened the color for any areas I had sanded through. Once this had dried, I sanded everything with 600G prior to spraying. Bear in mind that Target recommends sanding any pore filled wood with a minimum of 400G prior to spraying EM6000. As others have pointed out on the forum, some finishes may not adhere well to a surface sanded with such a fine grit. But I use EM6000 and have never had a problem following their instructions.

This is what the guitar looked like prior to spraying:
Attachment:
1-PreSpray.jpg

Prior to laying down any lacquer, I mask the bridge. In the past, I had trouble with my bridges staying put. I attributed this to removing the mask prior to buffing, which got the buffing compounds on the bare wood. Despite scraping the wood with a razor blade prior to gluing on the bridge, the joint still failed. I feel to get the bridge area leveled really well, the mask needs to be removed. So, to still level the bridge area and also keep my buffing compounds off exposed wood, I have started using two layers of tape for the mask. Once the guitar is sprayed, I remove the top layer of tape that has all the lacquer on it, allowing me to fully level sand the bridge area and buff. Once done, I remove the final strip to expose the wood.

I typically brush the first couple of coats on the soundboard rather than spray. I do this prior to pore filling to help protect the top. For this, I dilute the EM6000 a bit with water. As EM6000 is water based, it will raise the grain, so I don’t want the wood absorbing lots of this stuff. I simply brush the first coat on, making sure I cover everything. I later follow with an undiluted coat. Prior to spraying, I lightly hit the top with 320G paper to clean off any residual pore filler and smooth out the top. I don’t want to sand so much that I expose bare wood. If the surface is a bit rough, I don’t worry about it as it will get leveled later.

Water-based lacquer can be a bit finicky, and I struggled a bit early on to get a clean air supply. I have a 2HP 24G IR compressor with a 5 micron in-line filter. I found this filter needed a little help, so I added a disposable desiccant filter at the gun, which did wonders. I have also picked up a used Hankison refrigerator/dryer off Craigslist, which pulls even more moisture out of the line. I have a regulator at the gun, but I only use this for very fine adjustments. I set the primary pressure at the compressor. The gun I use is an Asturo Eco/S run at the manufacturer’s recommended pressure setting of about 20 psi.

I don’t use a traditional tack cloth when using EM6000. I moisten a cotton cloth with DA diluted with water (just damp enough to remove dust not soaking wet) and swab the guitar with this prior to spraying. It doesn’t take long to dry, and the DA helps the EM6000 bond better to the Zpoxy. I usually shoot 3 to 4 coats a night after work, waiting 45 to 60 minutes between coats. Prior to shooting on a subsequent night, I will swab the guitar with a mix of DA/water, which helps the new coats burn into the old coats.

I set my gun to shoot a 4” to 6” fan from 8” to 12” when shooting the body. When shooting the neck, I’ll dial down the fluid flow just a bit and narrow the fan. I always start at the top, spraying across and beginning and ending off each side of the guitar. I’ll spray a pass left to right, then overlap that pass by 30% to 50% as I move the gun back from right to left. The fluid flow has to be wet enough for the surface to look wet and shiney, but not so much that the lacquer sags. EM6000 looks milky when the coats are sprayed too heavily. Experiment on some scraps until you have a good fluid flow. Note that the earlier coats may be absorbed more by the wood, so you may not get a good, wet film. However, after a couple of coats, the film will start building on the surface, and you can better fine tune your gun settings. Getting a feel for the optimal fluid flow takes a bit of experience and experimentation, so don’t be afraid to tinker with the fan and fluid settings until you get a setting that really works. I have found I can get by with a bit heavier coat the first coat of the evening, but I dial back the fluid flow a bit for subsequent coats shot during the evening.

Attachment:
2-Spraying.jpg

Don’t worry about the surface being really rough after the first several coats and avoid the temptation to level the surface. We don’t want to sand through the lacquer. I typically won’t touch the surface with sandpaper until I have shot a half dozen coats.


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PostPosted: Thu Mar 24, 2011 11:22 pm 
Below is the actual routine I followed on this guitar:

Day 1: Swab with DA and shoot 3 coats of lacquer. Because I used Zpoxy on the back and sides and had a really smooth surface to begin with, these first coats went down very nicely. However, the top had not really been leveled since I brushed on a couple of coats earlier, so it looked a bit ratty.

Attachment:
3-Day1.jpg

Attachment:
4-Day1.jpg

Day 2: Swab with DA/Water and shoot 3 coats of EM6000. No issues here. Coats went on nicely.

Attachment:
5-Day2.jpg


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PostPosted: Thu Mar 24, 2011 11:24 pm 
Day 4: Leveled with 400G sandpaper. This first leveling is the only time I will use sandpaper this coarse. Scratches from 400G paper are easily visible after two or three coats. However, 400G makes the first leveling much easier as the surface can be pretty rough, and I know I’ll be shooting another half dozen coats or more. Leveling is done using a firm but somewhat flexible sanding block. I have been using a Holy Terror sanding block from Motor Guard for several years and love it. I don’t sand the edges at all until I am all done spraying and then only with 1000G paper. One brush with 400G paper along an edge could remove all lacquer.

Attachment:
7-Day4.jpg

A comment regarding sandpaper. Much has been said about using sterated sandpapers with water-based lacquer. I talked to Jeff Weiss at Target specifically about this, and he said that sterated papers from quality manufacturers should not cause issues. I use quality sterated papers from Klingspor during my prep and for leveling, and I have never had issues. The sterated papers have a lubricant that helps keep the paper from clogging, allowing the papers to be used dry. Water-based lacquers really do not like being wet sanded, so keep the water away. In fact, using sterated papers is less messy and allows me to clearly see how much material I am removing and when the surface is level.

When I level, I want to remove all the gloss from the surface. Be careful with deep pores as trying to level those could expose bare wood. There is no need to sand with the grain, so work the sandpaper and sanding block in various directions to make sure the surface is perfectly level. Below are before and after shots of leveling. See how dull the surface is? This leveled surface is really now the base that we will build the finish on, and if subsequent coats are sprayed well, the finish will build up nicely from here on out.

Attachment:
8-Day4.jpg

Following the leveling, I swabbed with DA/water and shot 4 coats of EM6000


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PostPosted: Thu Mar 24, 2011 11:25 pm 
Day 5: I inspected the surface to see if I needed to do any drop fills. The only places I saw were around the rosette, so I drop filled those with 3 applications of lacquer applied with a very small brush.

Day 7: As several days had passed since I shot lacquer and I had drop fills to level, I leveled the entire guitar with 600G sandpaper. By level, I mean sanding every surface (excluding edges) until the gloss was gone. This is an important point. EM6000 does not burn into previous layers like nitrocellulose lacquer. To help it burn in, scuffing the surface and swabbing with DA/water will help. If using fresh lacquer and only 24 hours have passed, I don’t worry about scuffing the surface, but if more than a day passes, I will dull the entire surface with 600 grit paper and swab with DA/water. Because of this lack of burn in, I try to shoot my final coats within 24 hours of my previous coats, and I make sure to shoot 4 coats on the last day to have enough layers from the final shooting to level, buff, and polish.

Day 8: I swabbed the guitar with DA/Water and shot 4 coats of lacquer. These are the last coats I shot on the top, giving it a total 12 coats.

Day 9: I swabbed the guitar with DA/Water and shot 4 more coats on the back, sides, and neck. These are the final coats, giving these areas a total of 16 coats. Target claims 100 hours to cure prior to buffing. I usually wait a full week but waited 10 days for this one. Spraying this guitar went very easily. I had no orange peels, runs, or sags, and the film formed without issues. Yeah!

Attachment:
9-Day9.jpg


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PostPosted: Thu Mar 24, 2011 11:26 pm 
Day 19: Time to final level and buff. I remove my top layer of tape from the bridge mask. For this last stage of sanding and leveling, I won’t use paper more coarse than 800G. I also make sure I have a really strong, bright light handy, so I can check my progress. I leveled the entire guitar excluding edges with 800G using my sanding block. Again, the objective is to dull the entire surface. Note below that the top is almost level, but still has some slightly low spots. I continue sanding until all the shiny spots are dulled and then switch to 1000G paper. I have finer grits, but I have found with my buffing compounds and setup, I don’t need to go finer than 1000G. The surface is now ready for buffing.

Attachment:
90-Day19.jpg

Attachment:
91-Day19.jpg

Attachment:
92-Day19.jpg


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Last edited by Ken C on Fri Mar 25, 2011 12:12 am, edited 1 time in total.

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PostPosted: Thu Mar 24, 2011 11:27 pm 
For buffing I use a 3” IR pneumatic polisher with Lake Country 4” foam pads. I start with Menzerna’s 2L Pre-Polish Paste applied using an orange pad. I later follow with Menzerna’s PO-91E Polish applied with a 4” white foam pad.

Attachment:
93-Day19.jpg

Polishing with a full circular polisher can be intimidating as speeds can be high and without care, the finish will overheat and burn or blister. The thing to recognize is that the polish needs to do the cutting, so enough polish has to be applied to the pad to allow it to do its job. If too little polish is applied, the pad will simply build up heat and the more the pad is pushed into the lacquer, the hotter it will become.

I mentally divide the guitar into sections and work on only one section at a time. For example, I began with the lower bout and worked on just one half of the lower bout. I give the pad a spritz or two of water, which helps keep it cool, apply the pre-polish paste to the pad, then work the pad over the area to spread the paste prior to turning on the polisher. I then turn on the polisher and work the polish into the lacquer going left to right, front to back, right to left, and back to front. I work it until the paste breaks down, usually a minute or so. I avoid spending too much time in one area. The surface will get quite warm to the touch, and this heat is what helps the finish flow and remove the scratching. We just don’t want it to get too hot. I usually find I need to repeat this pre-polish paste step one more time to remove the scratches. I used to do just one application, which removed all the scratches under daylight, but under a bright light in the evening, I could still see swirls. I started repeating this process, and all swirls went away even under a very bright light.

Attachment:
94-Day19.jpg


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PostPosted: Thu Mar 24, 2011 11:29 pm 
You can see in picture below what the surface looks like after one application of pre-polish paste. See the swirls at the near edge?

Attachment:
95-Day19.jpg

One more application of pre-polish paste and the finish is pretty much swirl free:

Attachment:
96-Day19.jpg

I use a couple of microfiber towels to clean the polish off. I use one for cleaning off the pre-polish paste and a separate towel for cleaning off the polish.

After I am happy with the section I am working on, I move to a new section and continue using the 2L Pre-Polish paste. I repeat this process until the whole guitar has been done. I’ll then wipe clean with my cloth and closely inspect, making sure I see no swirls or cloudy areas.

Attachment:
97-Day19.jpg


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PostPosted: Thu Mar 24, 2011 11:31 pm 
    When done with the pre-polish paste, I change pads to a white 4” foam pad and move to the PO-91E polish. The polish doesn’t heat the finish up as much, but I still spritz the pad with water prior to beginning. I will also work on a larger area, dividing the back into two sections instead of four. I put a dab of polish on the surface and before turning on the polisher, use the foam pad to spread the polish around on the surface. I then fire up the polisher and follow a similar procedure as earlier, working the polish into the finish until the polish breaks down. I then wipe the surface with my clean towel. After using this polish, the surface will be like glass with no visible swirl marks!

    Attachment:
    98-Day19.jpg

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    99-Day19.jpg

    Attachment:
    999-Day19.jpg

    Hope this little toot is of help. Both spraying and buffing can be intimidating at first and many simply have little idea how to go about it. I have several woodworking buddies who just don’t get finishing. People just can’t believe a high gloss, super clear finish can be done using water based lacquers in a home garage! But it can!

    Ken


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    PostPosted: Thu Mar 24, 2011 11:43 pm 
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    Joined: Sat Apr 10, 2010 10:50 pm
    Posts: 2281
    Location: Seattle
    Thanks, Ken

    Just in time for me to finish my guitar.

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    PostPosted: Fri Mar 25, 2011 8:32 am 
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    Joined: Sun Apr 19, 2009 9:26 pm
    Posts: 794
    Location: Williams Bay, Wi
    Best Toot Ever.

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