Finish that doesn't darken wood

[Peter Wilcox]

I'm making a checkerboard guitar body with alder and walnut - I need the alder to remain as light colored as possible (as in unfinished.) Wax does OK, but is not a very durable, protective finish. It seems that any penetrating finish such as lacquer or shellac darkens it too much. Is there a good finish that won't darken the alder much, or a sealer I can apply under lacquer or other finish to keep the color as light as possible?

[Eric Knapp]

I'm making a checkerboard guitar body with alder and walnut - I need the alder to remain as light colored as possible (as in unfinished.) Wax does OK, but is not a very durable, protective finish. It seems that any penetrating finish such as lacquer or shellac darkens it too much. Is there a good finish that won't darken the alder much, or a sealer I can apply under lacquer or other finish to keep the color as light as possible?

I'm curious, is that blond shellac? I just used dewaxed blond on some maple and there was almost no amber color.

-Eric

[David King]

You might try egg albumen as a sizing, Often a mixture of gum arabic, honey and egg whites (beat the egg whites stiff, no yokes allowed, and let that sit in the bowl for a while, pour off the albumen.
You can also choose from any number of other sizings like thinned rabbit glue or a first generation wb varnish (remember hydrocote?). Fishing rod makers use the WB varnish as a color preservative over the decorative threads they wrap the rods with. http://www.mudhole.com/ThreadMaster-Col ... ead-Sealer . it looks a little like thinned down Elmer's glue which might also work well. What about rubbing the alder with pickling wash or wood bleach solution?
Next time use holly instead of alder. <g>

[Peter Wilcox]

Eric - the actual piece has no amber color (it is platinum blonde dewaxed). The color of internet pics depends on the the lighting, the camera's color correction, the forum's color reproduction, and the monitor's set up. That pic shows more yellow than it should on my monitor. Also, now that the lacquer and shellac have dried more completely, they are not as dark as in the photo.

[Peter Wilcox]

Thanks David. Now that you mention it, I remember in the past Elmers has left light patches where I've failed to remove it all. I think I'll try that, if it doesn't lighten up the walnut. I assume I can spray lacquer over it with no adhesion problems?

[David King]

Oh it will lighten up the walnut too. I'd be a little worried about adhesion. I've noticed with most finishes that darken i.e. "pop" the grain that if you sand them back repeatedly and re-coat the wood will get lighter and lighter underneath. I have no idea what's really happening at the surface level but it's a trick I use all the time with thin CA glue. Somehow the previous applications start behaving like a sizing and keep the subsequent layers from soaking through. This approach will certainly work with your blond shellac as well.

[Beate Ritzert]

Some water based polyurethane acrylic laquers do not affect the color of the wood much. I would consider qualities which are intended for coating floors.

[Peter Wilcox]

Beate, I have some General Finishes WB topcoat - I'll give that a try. Thanks for the suggestion.

[David King]

The General Finishes is one of the few that does darken the wood considerably but worth a try.

[Alan Carruth]

There's a catch here: any finish that penetrates the wood and allows the light in will increase the color saturation, making it look darker, even if the finish itself is water clear and transparent. It's just in the nature of things that it shows up more on lighter colored woods. Traditionally the finishes that bring out the beauty of the wood best are clear and have about the same index of refraction as the cellulose itself, so that light reflects from the structure of the wood rather than the finish. Traditional oil-resin varnishes, or modern analogs, seem to do this best. Linseed oil itself also comes close. Shellac and nitrocellulose lacquer are not as 'deep' in that way, and can look 'veiled' by comparison, because the IR is not right. To my eyes UV cure polyester has too high a refractive index. This gives it a very reflective surface, but doesn't get the light into the wood: it's an impressive surface, but there's not as much under it.

The water born finishes I tried years ago tended to just sit on the surface. Usually the instructions tell you to seal the wood with something like epoxy or shellac, but if you leave that out you get a surface film with no penetration. The water is what actually wets the wood, so when it's gone the finish is not able to conduct light into the wood. Again, the 'veiled' look, but it certainly is white on white wood.

Personally, I'd find the clearest oil-resin varnish I could, and use that. There will still be plenty of contrast, since the dark wood will be color saturated as well, and you'll see the wood much better. At the moment I'm using Murdoch's Ure-alkyd 500 floor finish, from Sutherland-Welles, and it look great. It's almost as hard as nitro. The main issue I'm having is getting it to harden reliably on some oily woods, including some you don't think of as oily, such as Macassar ebony. Sealing the surface with CA seems to work, and doesn't look veiled to me.

[Peter Wilcox]

Thanks, Alan. Food for thought on wood penetration, refractive indices, transparency, water evaporation and wood figure. In the end I'm now concluding (by varying the contrast and brightness photographically) that for my purposes the contrast between light and dark is not as important as I surmised. Lacquer, lacquer over Elmer's, shellac, and the General Finishes WB top coat all give fairly equivalent darkening on my alder.

What I'm trying for is known as the cafe wall illusion: http://www.michaelbach.de/ot/ang-cafewall/ It seems the ratio of the width of the lines between the squares to the width of the squares, and the luminescence of those lines being somewhere between the light and dark of the squares, are what maximize the illusory effect.

[Peter Wilcox]

Alder, walnut and myrtlewood - seems to work as a rectangular shape. I'll see what happens as a guitar shape with finish - probably not as striking an illusion.

[Randy Roberts]

Wow Peter,

It onlyt took about 15 seconds of looking closely at that and I was seasick and couldn't walk straight.

I would recommend including a bottle of Dramamine with the guitar.

[David King]

That's crazy! better cover it up with a sheet when you saw out the shape lest you get pulled into the bandsaw. Combine it with an on-board Peterson tuner and you'll be felling whole audiences as soon as the smoke clears and the strobe light comes on.

[Peter Wilcox]

White Rabbit will be the first song played on the instrument.

[Mark Swanson]

Cool! Good one too.

[Bob Howell]

You might try egg albumen as a sizing, Often a mixture of gum arabic, honey and egg whites (beat the egg whites stiff, no yokes allowed, and let that sit in the bowl for a while, pour off the albumen.
You can also choose from any number of other sizings like thinned rabbit glue or a first generation wb varnish (remember hydrocote?). Fishing rod makers use the WB varnish as a color preservative over the decorative threads they wrap the rods with. http://www.mudhole.com/ThreadMaster-Col ... ead-Sealer . it looks a little like thinned down Elmer's glue which might also work well. What about rubbing the alder with pickling wash or wood bleach solution?
Next time use holly instead of alder. <g>

Over the years I built Windsor chairs with many types of glue, HHG, Elmers, PVA. I was finishing with shellac and Splotches left on the seat could be a big problem. I discussed this with friends and we realized a washcoat of the glue used for assembly, would at least give us an even finish. FWW has articles for using PVA, HHG, and shellac as wash coat to even out stains. Hence I used it to cover up glue runout.
At some point it limits the "depth" most finishes give the wood. Don't know just where but I have seen it kill the "depth look". That I did not like.

[Clay Schaeffer]

A cab lacquer may give a fairly white appearance to the alder and still give a nice contrast to the walnut. Cab lacquers don't yellow as much as other lacquers. Mohawk sells it in rattle cans if you don't want to buy a whole gallon.