Stabilizing partially finished burl

[jeporter02]

I have a piece of redwood burl that broke off a live edge coffee table that I'd like to turn into hybrid blanks. The burl was cut by my grandfather, who owned a sawmill in the California redwoods, over 70 years ago, so it has sentimental value for the family. The coffee table was finished, though it appears only on the top and sides. The underside of the piece of wood still looks raw. I don't believe the burl was stabilized before it was made into the table top, so I need to stabilize the piece now. My question is: how best to remove the finish on this gnarly burl before stabilizing it? I can sand the top, but the sides are too craggly. I could use a stripper, but I worry residue from the stripper may react with the cactus juice and inhibit the stabilization process. I'm not certain what the finish is. The table was made by a pro woodworker about ten years ago. Any suggestions?

 

[KateHarrow]

If it were me, I would ask Curtis from TurnTex directly if he had a suggestion. The cactus juice itself might even dissolve that finish, who knows. You might be just fine sanding all of the easy sides and chipping out the remaining bark inclusion, drying it, and stabilizing as normal

 

[MRDucks2]

I have a piece of redwood burl that broke off a live edge coffee table that I'd like to turn into hybrid blanks. The burl was cut by my grandfather, who owned a sawmill in the California redwoods, over 70 years ago, so it has sentimental value for the family. The coffee table was finished, though it appears only on the top and sides. The underside of the piece of wood still looks raw. I don't believe the burl was stabilized before it was made into the table top, so I need to stabilize the piece now. My question is: how best to remove the finish on this gnarly burl before stabilizing it? I can sand the top, but the sides are too craggly. I could use a stripper, but I worry residue from the stripper may react with the cactus juice and inhibit the stabilization process. I'm not certain what the finish is. The table was made by a pro woodworker about ten years ago. Any suggestions?

You may want to reach out to Curtis at TurnTex if you use Cactus Juice for likely the best qualified opinion.

If my burl, I would go ahead and sand off the the flat surface removing all of the old finish. Then I would put a portion, maybe an inch, of one of the finished ends into some CJ to soak and see what happens to the finish and the CJ. (Note this is on the bench top, not under vacuum)

Liquid CJ tends to be a bit of a solvent. If the finish loosens from the surface and floats around in the CJ it could be a problem as it would then be suspended and drawn into the wood under vacuum or post soak. This would give unpredictable results.

It could also loosen and either float or sink. Both of these could be accommodated by letting the whole piece soak and allowing the finish to sink to the bottom or rise to the top of the container. You the either skim the top and remove the wood or just remove it (if it sinks) and then put it in in contaminated CJ and process as normal under vacuum then soak then cure or whatever process you use.

The thing I would not do is just throw it in a chamber and see what happens under vacuum. The finish can give of VOCs that could be flammable and could damage your pump even if not flammable in addition to getting unevenly pulled into the wood.

In most any case, you are going to lose some stabilizing resin as I would not use it again due to the likelihood of contamination, even if you come up with something that does work.

 

[egnald]

There are a few things you could do to maybe get a read on what the original finish might be. If you can find an inconspicuous spot to test on this is what you could try.

First, use a Q-tip to apply a couple of drops of boiled linseed oil. If the wood absorbs the oil the finish is likely some kind of oil like walnut oil, linseed oil, tung oil, etc. If it beads up then it is probably shellac, polyurethane, lacquer, or old fashioned varnish. (Note: Danish Oil is not a true oil finish as it is usually a varnish mixed a solvent and some kind of oil).

If it isn't oil, then using a different Q-Tip, rub a couple of drops of acetone on another spot. If acetone beads up the finish is a polyurethane. If it doesn't bead up, wait a few minutes and then touch or scrape the spot with your finger. If the spot is not sticky the finish is most likely lacquer as lacquer should dissolve completely in acetone, but acetone would make shellac and varnish get kind of sticky.

If it isn't lacquer then try rubbing a few drops of denatured alcohol in another spot. If the finish dissolves quickly the finish is likely Shellac. Varnish will dissolve in denatured alcohol too, but not nearly as quicly as Shellac.

This may also help:
1) Denatured Alcohol - dissolves Shellac
2) Lacquer Thinner - dissolves lacquer, shellac, and water-based finishes
3) Xylene - dissolves water-based finishes
4) Naptha or Turps - dissolves wax finishes
If none of them dissolve the finish it is a finish that cures via polymerization like Polyurethane, Plastic Resin (like Epoxy), or a Varnish.

Good Luck. It is a beautiful piece of wood!
Dave