Second rosette practice

[ken cierp]

H2o is a catalyst and/or activator for CA, the water will make the wood swell not the glue. I would think Michael should know better – CA will definitely stain Spruce and other soft woods a bright florescent yellow green if not sealed. Like the Taylor factory I use nitro lacquer – I do not know if shellac works for that purpose – but I would not take the chance. The stains are truly ugly and there is no known way to remove them – they are deep into the grain, after all the capillary action is what makes CA work so well.

[John Link]

Yes, it was the water that swelled the rosette strips, not the flooding with CA.

I did not know water was an activator of CA. Michael mentioned the two worked together and assumed the viewer knew why. Now I wonder why I pay all that money for CA accelerator.

It was definitely a spruce top, apparently a hybrid from British Columbia that goes by the name of Lutz spruce, given that Lutz is what is sold by the source he named for the top he was using.

In my 13 years as a nitro spray boy, we considered shellac to be the most powerful sealant for isolating stains already on surfaces, and protecting clean surfaces against staining. That does not mean nitro would not work too. Nor was there such a thing as CA in the 50s and 60s. (Yes, I am older than dirt.) It wasn't even an abbreviation for California.

Think I'll do a little three way test on some scrap - shellac, nitro, and nada, with and without water. (I wondered at the time if wetting the wood might not have protected it in some way or another.) I'll take pix and post them if Ken will tell me where.

[ken cierp]

I use CA to seal spruce mainly because that is what Taylor uses on 250 guitars per day. And I really don't like shellac because of the residual coloration it tends to leave on the soft wood where it is applied, requiring special care to remove by deep sanding in order to prevent color value stains from appearing late in the finishing process. Lifes too short, clear/invisible lacquer is the way to go for me. Plus its seems if you need moisture to expand the rosette or tighten the channels, why not just use a water bone adhesive?

[John Link]

Interesting Ken. I cut the "water" test piece with one side of the channel a little wobbly, to create a practical need for swelling the strips. Then I found the channels on both pieces were a little wide, just because that's the way it worked out and I didn't want to fuss around creating a perfect set of strips for the groove I had cut.

For the reasons Ken prefers nitro, someone who plans to french polish might prefer shellac, assuming both perform their intended function of protecting the spruce. Go with the one that works with your final finish. Nitro has the advantage of coming ready mixed with a long shelf life.

In any case, I deliberately went with a "disaster" scenario of sorts in that I pretended there was some sort of unplanned spillage of the CA in both cases, the kind of thing we never want to happen, but does. Both looked pretty messy after I was done. They are under mild clamp and drying now. When cooked I will photograph and post here.

If nothing bad happens it does not really prove anything, though. We all take steps to prevent the really bad things, even if they are just 1 in 100 events.

[John Link]

Ken's point about water came home when I unclamped the two samples. The wet one was not and still is not dry enough to level the strips. Maybe tomorrow. Meantime, the dry was ready. The extra spillage made the inlay hard as a rock, but I leveled it rather easily nonetheless. The slightly wide channel doesn't look that bad, though it would be unacceptable on an instrument. (Wetting the other sample filled the channel and the wobble on its uneven side.) What really looks bad is where the CA penetrated the unprotected spruce and darkened it, unevenly. The unprotected bottom side - admittedly the site of a disaster of sorts - is slightly darker than it appears in the photo. The top side experienced the same disaster, got the same amount of final sanding in the leveling process, and looks fine.

Dry.jpg (58.82 KiB) Viewed 3208 times

Comments: There are some tiny white specs on the left caused by the flash. Neither the photo nor my eye can detect a difference between the top nitro and shellac sides. Nitro used was Behlen's Instrument Lacquer out of the can several years old; shellac was light blonde I mixed about two weeks ago.

When I protect a channel I make sure the sealer covers the exposed end grain in the channel. After all, that is where all the little tubes that conduct fluid are in the wood. I'm not sure merely cutting the sealer to the top edge of the channel would provide the same protection - and I would not waste my time testing because I doubt it would.

[ken cierp]

Thanks for the tests John -- Its been long time since I used CA on Spruce without sealer, I can't recall how long it takes for the staining to occur -- about a week I think? Taylor pulled their Factory Friday videos but I seem to recall that they sealed the entire channel and off the channel edge about 3/8"

[John Link]

The wet sample finally dried and I just leveled and photographed it.

Wet.jpg (65.24 KiB) Viewed 3198 times

The water appears to have had a protective effect. The variation of color in the bottom half found in the dry sample does not appear in this one. Perhaps the water prefilled the tubes in the wood so that the CA could not easily travel down the grain. It is not a method of protection I would ever choose over applying a proper sealant, though.

The water swelled the strips so that they filled the part of the channel that was simply too wide, between the "d" in "nada" and the "o" in "h2o", but where I introduced small wobbles in the lower edge outside this section, the water was not particularly effective at filling those tiny gaps. Some spruce dust mixed with Titebond might address those gaps somewhat (or lacquer burn in stick); no wobbles in the first place, of course, would be the best way to go. So the water method is best reserved for instances where the channel gets consistently too wide and/or the rosette materials too narrow.

I will set both of these samples aside and see how they age.

In Michael Collins defense, I will say he did not provoke disaster like I did. He used a flexible pipette attached to his bottle of CA and applied glue carefully. I would post stills from his DVD showing what he did except I want to be careful not to trample in the slightest on his and Jamie Boss's copyright. It is a very worthwhile video that is well produced.

My bottle of CA had locked up last month and I had used pliers to get the top off, taking the long, precise snout with it. So, I poured my CA on crudely, since I wanted to test the worst possible situation anyway.