Official Luthiers Forum!

Hi

So probably a daft question, i notice that my spruce top and mahogany are very light when first finish sanded, but then slightly darken when left for a few day.

I much prefer the soundboard nice and light and the same with the mahogany, so does it make any difference if I make the effort to put finish on quickly after sanding or will it just darken fairly quickly anyway under the finish?

TIA

Sent from my SM-A715F using Tapatalk

Photo of the mahogany bindings that have darkened over the last days

Sent from my SM-A715F using Tapatalk

The wood will still oxidize under finish. I actually changed the bridge on a guitar to a new design and re-finished. You could see the clear footprint of the old bridge for a month or so, but not much longer.


Sent from my iPhone using Tapatalk

Some finishes have UV inhibitors that will slow the effects of light and some finishes will slow the effects from oxidation, but I don't know of any that will stop it. It is better to finish a piece after finish sanding (final prep and "nib" sanding) because that is when the surface is in the best condition for finishing.
When these discussions come up it reminds me of Ivanov's "Snow Parlor" that was on the Dream guitars site. It was an exercise in white on white which eventually will look like the Huskies had their way with it - yellow on yellow
Here is a discussion of people's frustrations and limited successes with keeping the color which might be worth reading:
https://www.aawforum.org/community/inde ... ood.12894/

For many violin makers, getting the wood darker under the finish is a month long process. Most use light boxes. I've had a bunch of wood that wasn't that photo-reactive, so on the 5 string I finished last Christmas I used water with some wood chips from the Cherry back, and brushed that on the belly, along with water with wood ashes in it, I suppose that should be lye. It worked. But violin makers are looking for a certain look. The darker ground color that the varnish is put over is the key to that. A really blonde top or back would really stand out. A red/brown varnish over a white maple back will look new, or sterile. Many buyers might stay away from it. There are many light, or blonde guitars out there, along with any species imaginable.

Guitars don't have the same looks stigma, as far as color and species go.

So it's just a matter of what you like. If you do use the sun or Lightbox , and tannins, and lye, or the nitrates and stuff some violin makers use; the one thing that you will gain, (as long as the nitrate doesn't oxidize your wood to punk) is that the color you have when finished might not change a whole lot later on. Some woods change color just with age, but maybe along the same line that they did in the light box. Those that change mainly from uv will NEVER get the uv exposure you gave it again.

_________________
Why be normal?