Acoustic Guitar Construction

Lookin' good!

Any problems using the waterborne?

None that I can tell yet. It looks like it's going to finish out nicely.

I have an every day player that is holding up nicely, it was finished with the older version of Target WB spraying lacquer. That said -- I no longer use any water borne products and my reason is a simple "the water" What I noticed when applying the WB chemical is that the guitars were actually changing shape tops and backs were puffing up/out. Which made me wonder what was happening to the glue joints on the braces etc.? I have no other data or facts -- but frankly that was enough for me, to many variables to cope with already, no need to inject another. So for me anyway, its solvent base finish and I love the forgiving nature repairability of nitro lacquer.

The guitars look great.

I have found that Em6000 buffs out nicely to a lacquer time type deep gloss. EM6000 is pretty forgiving as to regards to repair, more so than other water base finishes. It is not quite as easy or forgiving as solvent based lacquers but relitive to other WB finishes it is close. I use the product on wood sealed with zpoxy or shellac and have not had any odd mositure problems. The rough neck sets I performed before spraying we still set after spraying.

John

I may move this over to the finishing section -- but anyway here's how you can test burn-in and potential repairabilty. Which the old Target WB failed. Now this is done with a brush but reveals the chemical properties the same as when a applied with spray equipment. Brush on several coats of the product waiting the prescribed time intervals. Alternate the direction of the brush stroke each coat -- coat then the next coat 90 degrees -- normally you would not do it this way. After six or eight coats let it dry for a couple of days. Now here's the test take an orbital sander and wear down the finish to bare wood in the center of the test piece. Look at the edges of the sanded surface. With a chemical like nitro the cross link burn-in feature melts the previous layers forming one single coating, this test will reveal no witness lines. On the other hand I have yet to find a Water Borne product where it is not clearly apparent that each coat is laying on top of the last coat -- witness lines at each layer.

In the auto industry when WB came of age this was a huge problem in fact (this was years ago) if there was a need for spot repairs, super high solvent nitro was used to assure burn-in and prevent witness lines. I assume things are different now.

Ken,

That would be an interesting experiment. When I start to finish the harp ukulele I will perform the test as you describe. My experience is that EM6000 when spraying at least every day burns in well. Also On my last guitar, I had an area where I had to re-spray an area 1 week later. I have seen no signs of witness lines between the old and the new. I know what you are talking about. I used KTM-SV a water based spar varnish; To avoid witness lines the last coat needed to be a dead level surface and sprayed perfectly because if you sanded or buffed through the last coat anywhere one could see witness lines.

My only experience using the WB finishes is in cabinetry, so I wanted some input from people with experience using it on different projects (like guitars!).

Workplace/environmental conditions is what forced the change.
Quite often the customer specified it, too. For example, quite often the unit was built and finished "on site". The entire room was sealed off as a "booth". So lacquers were no-go, and the WB had less time involved than the oil-based finishes.
Still, it was not without compromises.

Just wonderin' how it performed under the parameters of smaller, more detailed construction.

Thanks!

Rob