Burst finishes in the old days?

[Rick Liftig]

Here’s a puzzler:

there must have been a time (say in the 1930s or 40s) where burst finishes were done without spray equipment. How would this have been done? Varying alcohol dye strengths applied in overlapping applications? Or sanding back and re-applying? Or simply, have spray units (possibly hand operated atomizers) been used for far longer than I ever dreamed?

Thanks in advance.

Rick

PS - and, just thinking out loud: could you do a burst effect with a simple spray bottle filled with say an alcohol or shellac based stain?

The Bottom line is that I would like to avoid the spray process. I do not have the room for a spray booth, the proper ventilation, the equipment, or the temperature\humidity controls in place to do a properly controlled spray finish. (And have no urge to go there!)

[Rick Liftig]

And I just found this thread: https://www.mimf.com/phpbb/viewtopic.p ... 051#p51051 with a great explanation (as always!) from Alan Carruth.

Alan: you know an amazing amount of stuff, and you explain it so well! We should scoop up all of your wisdom scattered among god knows how many fora and create an encyclopedia of luthiery! (In our next lifetime, maybe)

[Rick Liftig]

It Looks like the relevant search phrase is “hand rubbed sunburst finish.”

[Rick Liftig]

And doing the deep dive yesterday, I discovered many answers to my question on the internet. Looks like I need to order a few pieces of wood to practice on before I finish the new build.

I will likely be staining with transtint or colortone pigments dissolved in alcohol, then topping with shellac. Questions remain as to whether to put a sealing coat of shellac on first in order to avoid lines. To this end, I’ll definitely work light to dark. The top will be french polished.

The sides, back and neck of the guitar are mahogany and I am still pondering how to treat those areas so that the wood grain is not hidden by the stain, yet still blends in nicely with the darker tints.

Decisions, decisions. Happy New Year everyone!

[Alan Carruth]

There are two basic ways to go about this; color on wood or colored finish. Coloring the wood directly accentuates things like run out and changes in density. On curly wood, for example, it makes the curl stand out because the end grain absorbs so much more color. On soft woods it effectively reverses the 'natural order': light colored soft earlywood absorbs more color and becomes darker than the normally dark latewood. You see this commonly on stained fir plywood, but I've seen it on guitars where they've sprayed color onto the bare top. The ray pattern stands out.

Color on bare wood 'locks in' curly figure. Under a clear finish the light reflects differently depending on the direction of the run out, so the chatoyance of the wood moves as you moved the piece. This is particularly apparent at the joint line in a curly back, where the light and dark lines switch across the joint. With color on the wood the 'dark' lines will always be dark, no matter what angle you view the wood at, whereas with color in the finish they can shift from one side to the other depending on the angle.

Color in the finish absorbs some light, so that the 'bright' lines end up not being as bright; there's less contrast. The 'hammered' look of quilt figure can be very strikingly three dimensional under a clear finish, but is less pronounced under colored varnish. OTOH, clever use of different colored layers can produce a 'dichroic' effect under colored varnish, where the 'light' lines show up as, say, more yellow, while the dark parts are browner. Something of this effect can be obtained by using different dyes on the wood.

Dyes are often not as color fast as pigments, but pigments block more light in general. It's hard to get the really brilliant effects of dyes using pigments, but if the dyes all fade out to some sort of sickly green over time you mi8ght not like that either.

I'm a colored varnish guy myself. I try to seal off the wood as well as possible before putting on any color. I've gotten good results using a French polish type pumice fill on the wood, using shellac or some other resin dissolved in alcohol as a binder. This is built up only to the point of filling the end grain and producing a slight gloss on the surface. I then use oil-resin varnish to build the body color. Shading can be done either by wiping back the color where you don't want it, or glazing with oil colors in select areas between coats. Finish off with a few thin coats of clear varnish to have something to rub back without taking off color. It's hard to get a really saturated color layer this way and still keep the finish thin. I'm always trying to improve...