BLO on Cherry

[Prashun Patel]

I'm making a table out of cherry. I'd like to finish with BLO followed by wiping varnish.

Is there a risk of blotching?

If yes, then can I washcoat with WAXED shellac (i.e., Zinsser Bullseye) or do I have to use dewaxed?

[glenn bradley]

I experienced blotching with BLO on cherry when I made my test boards. I suggest you make test boards as everyone should; why guess? Some cherry is more blotch prone than other cherry. I used Seal Coat hit 1:1 with DNA as a wash and it came out great.

This article pretty well covers it: http://www.taunton.com/finewoodworki.../011200052.pdf

[Prashun Patel]

Thanks, Glen. I read that article too. I'm prepared to wash coat with shellac, but I don't see why I can't use WAXED (which I happened to have lots of on hand) if I'm topping with BLO and varnish...
Thanks

[Jim Becker]

There is no point in putting BLO on the wood if you seal it first...oil needs to soak in to give its effect. "Blotch" is merely the figure of the wood absorbing the oil at different rates. If you don't like the look, don't use the oil.

That said, you can use waxy shellac under oil based varnish that does not contain polyurethane resins. For topcoating with poly, or anything water borne, you must use dewaxed shellac.

[Steve Schoene]

I don't quite understand why, if blotching is the issue, BLO is in the sequence. The whole purpose of BLO is to enhance figure--ie. to enhance blotching. I'd go directly to the oil based varnish over the shellac wash coat. For the most blotch reduction, the shellac should be very light in color, which means something like super blonde or ultra blonde. If the varnish doesn't contain polyurethane, but is one of the conventional resin varnishes, then you can use shellac with wax.

[Prashun Patel]

Thanks, Steve. I lke the color that BLO adds. I think I will just live with any 'blotch'. I've completed a couple test pieces in BLO alone and I really like the effect. It's my first piece in cherry, and I while I've heard that a lot of people like BLO on cherry, I was unclear whether it required a sealcoat.

[glenn bradley]

I think we are confusing the desired figure with those unattractive blobs that appear on blotch-prone woods. I really like cherry's figure but not the blotches that look like something is already spilled on it ;-) This would be an area that looks like one thing but another two-tone appearance presents itself with an absorbed finish.

The sealer mix I make out of shellac is quite thin and I still get plenty of oil absorbtion. I just don't get the dork patches in the middle of what I thought was a light patch ;-) Not all cherry does this but I have had enough bad experinces to just use the sealer prior to the rest of the finishing protocol. Maybe the cherry I get in my area is just more of a problem(?).

Another advantage for me is in my climate BLO will weep for over a week. The sealer shortens this to a few days. As the droplets appear I just wipe them down a few times a day for a few days. Once the BLO smell is very faint, I move along. Another solution for me is to just use waterborne dye.

[Prashun Patel]

Thanks for the clarification. I'll washcoat.

[Joe Fusco]

Shawn,

I’m one of the few remaining who saying, go ahead and use that waxed shellac as your wash coat. In 28 years now of finishing I’ve never once had a polyurethane or waterborne finish fail because of waxed shellac under it, never. Also, in my 11 years online I’ve gone round and round with others on this topic , but no one has ever sited personal experience with a failure either.

So have some fun and use that shellac.
http://www.josephfusco.org/Articles/...tch_Stain.html
http://www.josephfusco.org/Articles/...d_shellac.html

[Steve Schoene]

Clearly the manufacturers that warn against using their products over shellac (with wax) have done the research--it is in their interests to have their product work well, and also in their interests to say that it works in the widest possible range of situations. Therefore if you start with the idea that there is no difference in adhesion between to waxed and dewaxed shellac that is simply and unequivacally wrong.

Without statistically valid scientific tests you really can't make the case otherwise. Collecting a few internet "samples" and the experience of one or a half dozen finishers over the years doesn't count to give valid evidence.

So the only real question is whether the difference is "meaningful", a much different thing than "statistically significant". All you can argue is that in uncontrolled experience you haven't seen a difference. But there is zero reason to accept your advise for action. Why?

Since dewaxed shellac is available in almost all "flavors" (short of very unrefined types like seedlac) there isn't much reason to have the waxed shellac laying around especially since dewaxed flakes generally cost the same as flakes with wax. Therefore, there is very little, if any, reason to use waxed shellac in the first case. In other words, if it doesn't cost anything (or costs very little) to take the safer approach, then do take it, even if the probability of actually seeing a benefit, or avoiding a problem, by doing that is quite low.

"Failure" can take other modes than just having the finish peel off in sheets. Suppose the standard cross hatch adhesion tests give a 98% success over dewaxed shellac and a 90% failure over shellac with wax. Most of the time--a very high percentage even, there is no failure over shellac with wax. But in just a few cases there might be problems, and these problems may occur so far down the line they might never be associated with the kind of shellac used under the poly varnish. The finishes over shellac with wax, may just get dinged up just a little more easily for example. Maybe they need refinishing after 35 years while the same finish over dewaxed shellac might look good for 40 years.

Consequently, I will still give the only logically correct advice. Use only dewaxed shellac under polyrethane varnish or waterborne finishes.

[Jim Becker]

Thanks for the clarification. I'll washcoat.

Shawn...as always...try it on scrap of the same cherry you are using before you commit to any finishing regimen.

[Joe Fusco]

Manufactures in general say just about anything to CTA, I like the one that says use of one of their products can cause "sudden death"???

Yet everyday millions of people use it

Good luck with your next finishing project.

[Mike Conley]

The sealer mix I make out of shellac is quite thin and I still get plenty of oil absorbtion. I just don't get the dork patches in the middle of what I thought was a light patch ;-) Not all cherry does this but I have had enough bad experinces to just use the sealer prior to the rest of the finishing protocol. Maybe the cherry I get in my area is just more of a problem(?).
.

What # cut do you use as your sealer?

[Howard Acheson]

Just looked at the latest Fine Woodworking Magazine. They have an excellent article on finishing cherry. I suggest you go to your magazine seller and get a copy. It will tell you step by step how to minimize blotching when finishing cherry or other blotch prone woods.

[Prashun Patel]

THanks, as always, Howard. I read the article. Basically, they corroborate what everyone else has said:

Washcoat with shellac improves the overall finish every time - even under gel stain.