Shellac

[Lew Barrett]

There's a nice article on the many uses of shellac in this month's excellent (number 200) issue of WB. Of it's many uses, the author points out that shellac makes a good sealer if one is using traditional boatyard bedding compunds such as Dolphinite or Interlux bedding compound.
One of my problems over the years with oil based compounds versus the "modern" solutions like Boatlife and Sikaflex has been that although I prefer the more benign qualities of Dolphinite and the like, I have found that they dry out in use. The author of this article explains why (the wood, especially end grain, leeches the oils out) and instructs that wood and faying surfaces might well be sealed with shellac. He gives a few reasons for shellac versus red lead, but clearly, red lead would work as well or better for some applications if one has the time to wait for a cure, is working below the water line, or where red lead won't present a cosmetic problem. The issue for me has been in places like window trim where most paints and primers would be both cosmetically inappropriate and difficult to use due to extended cure times. Shellac provides a fast and cosmetically satisfying solution in those instances as it significantly reduces the leeching of the bedding compound's essential oils. I need to give it a try "next time." I'm sure the old salts like the Band of Bobs, Canoeyawl, Jay, Dr Fleming or any of the other old tars knew this and tried to tell me, but this article really drove the point home.
The rest of the issue is particularly well done. I think they put special energy into making "200" a landmark copy.

[Nordicthug]

If time isn't a big deal, sealing porous surfaces to be bedded is much better done with varnish or oil based paint. We in the repair yard saved old varnish and paint from the paint shop for this.

I have lifted moldings and fittings and opened joints where the wood was sealed with shellac or sanding sealer to find the compound dried out after only a few years, whereas in varnish and paint sealed joints the Dolfinite was wet and sticky after 15-18 years.

I didn't have the opportunity to try the newer waterproof clear urethanes, I expect they'd be good too. Shellac just yeilds too easily to water to be trusted over time as does lacquer sanding sealer.

Your mileage may vary.

Gerry

[Lew Barrett]

Thanks, Gerry. The author's point, and your experience may be of significant value, is that shellac is handy when you don't have the time to allow a long oil product (like varnish) to cure. I would not use or substitute shellac as a sealer below the waterline, but would like to find a way to keep oil based bedding compounds compliant and water tight in applications like exterior trim. So far my experience with Dolphinite have been disappointing there.

[Nordicthug]

Thanks, Gerry. The author's point, and your experience may be of significant value, is that shellac is handy when you don't have the time to allow a long oil product (like varnish) to cure. I would not use or substitute shellac as a sealer below the waterline, but would like to find a way to keep oil based bedding compounds compliant and water tight in applications like exterior trim. So far my experience with Dolphinite have been disappointing there.

I would experiment with a waterproof clear urethane. My limited experience is that they dry quickly.

To help paint and varnish to dry more quickly and as they won't be visible, try thinning 10% - 20% or so. They don't need to be resistant to wear and abrasion or look good, only keep the oils and soaps in the bedding compound from drying out. Sealing both sides of the joint is good, as well.

For a bedded joint that's going to be used for a loooong time, its good to be patient when prepping it.

That's why God gave us pipes, coffee pots and friends to sit and chat with.

Gerry

[Canoeyawl]

Dolpninite leaves a lot to be desired these days.
Years ago out behind the boat shop there was a collection of derelict boats. This was an ideal place to escape the toil of the shop and enjoy a smoke or whatever, but inevitably we would start looking over these boats that were built fifty or more years before with a critical eye.
The thing that stands out most from that experience aside from the obvious superior skills was the bedding compounds were still pliable and doing their job even though the boats had long ago been left to the elements. The wood under the stuff was still sound while surrounding these areas the wood was long ago split and checked from the sun.
These bedding compounds were surely white lead based.

The old bedding compound recipes were simply whiting (finely ground chalk) and white lead paste with linseed oil to suit. Most likely made up by the builders working from an old hand-me-down recipe.
My father tells of mixing the paint for the house using fifty-pound kegs of white lead and mixing it up in a washtub with boiled linseed oil. We still have the house and it is well preserved. Of course we are all probably brain damaged also…

This leads me to the question - Has anyone mixed white lead paste with Dolphinite,
or their own concoction?
Red lead is not the same; in my experience it seems to chalk off pretty rapidly and makes poor bedding.
A great primer, but a poor bedding compound.

[Jay Greer]

Well, although I have been using shellac for over fifty years for various purposes from sealing wood to French Polish, I was happy to see the article in WB which confirms my own beliefs about the material.
Jay

[Lew Barrett]

This is the crew I'd hoped to attract. Jay will surely remember, and I have already said here, my experiences with Dolphinite have been less than fully satisfying. I'm not the world's greatest joiner by any means, but I enjoy the challenge and I work hard at it, so when the water gets in a season or two later, my thought is to look to the compounds I used. I've had better luck with the newer products.
The problem with mixing in lead of course, if one relates back to the Woodenboat article, is that it defeats the purpose of a greener solution. But my own efforts at green solutions don't seem to work even relatively short term. I think proper sealing makes good sense, regardless. Thge new "red lead substitute" whatever that stuff is, seems to be red/orange tinted primer, and little else.
Canoeyawl; most of Rita's old, tried and true bedding compounds are now pretty much gone.

[Hwyl]

Dolphinite used to depend on some carcinogenic compound to make it work well (I can't remember which one, looked it up PCB's) they took that out in the 80's. It's no longer anything like as effective, but one doesn't get cancer from it. Not a bad trade off, I would suggest though that it is still recommended because of it's former (deadly) glory.

[Canoeyawl]

Shellac is a staple in my shop. Introduced to it as a child I use it for many different tasks. As a sealer it is excellent although if I have the luxury of time thinned varnish is usually my choice.
I always varnish before painting...

I also use it (Shellac) to protect iron tools if they are not in constant use. A very thin 1lb cut applied to guns, knives, saws and etc will readily wash off with alcohol yet is impervious to petroleum based oils that may be used as a lubricant.
This is tried and true and directly from a page in L. Francis’ Common Sense book.

Red lead primer is still available from Kirby’s. I have found that if it is mixed with 20% varnish it becomes a serviceable paint with no need for an overcoat.

[Bob Smalser]

Much as I love shellac, I'm skeptical of its durability as a bedding compound. Plus the good stuff is expensive:

http://www.shellac.net

Nor am I a big fan of the whiting-white lead-raw linseed bedding compounds I grew up with, or their overpriced modern equivalents. They can dry out and need to be checked periodically by pulling off the hardware. Of course that chore often gets negelected at the expense of the wood beneath.

http://pic3.picturetrail.com/VOL12/1104763/7534648/98698786.jpg

http://pic20.picturetrail.com/VOL12/1104763/7309305/296234935.jpg

I've been using polyurethane plumber's caulk for 3 bucks a tube. Inexpensive so you can use it liberally, lasts forever, seals thoroughly and remains flexible. This goo is adhesive, but not anywhere near as adhesive as 3M5200. To use it and still be able to dismantle what you bedded, prime and paint both parts to be bedded first. With a utility knife, heat gun and pry bar you can separate the parts at the expense of the paint.

http://pic20.picturetrail.com/VOL12/1104763/7534648/98698784.jpg

To minimize adhesion, hardware gets a coat of paste wax first, and the hardware retorqued after the compound cures.

Bedding Hardware (http://www.woodenboatvb.com/vbulletin/upload/showthread.php?t=9382)

[Lew Barrett]

I have less issues with hardware that can be periodically removed, and will be, when recoating for varnish or paint. It's the wood trim that drives me nuts. I would never use shellac or varnish alone as a bedding, just as a sealer of course, and like most, I always have varnish laying around. It's the lack of durability in the traditional bedding compounds that is frustrating. Once the wood trim is down, usually at great difficulty and expense to any existing finishes, one has to re-coat with varnish, only to take it all down again a few tears later to re-bed. It's that, which drove me to polyurethane compounds.
Thanks for the wax tip, Bob. That's sensible, and useful.

[ddeaton]

http://pic3.picturetrail.com/VOL12/1104763/7534648/98698786.jpg

http://pic20.picturetrail.com/VOL12/1104763/7309305/296234935.jpg

I've been using polyurethane plumber's caulk for 3 bucks a tube. Inexpensive so you can use it liberally, lasts forever, seals thoroughly and remains flexible. This goo is adhesive, but not anywhere near as adhesive as 3M5200. To use it and still be able to dismantle what you bedded, prime and paint both parts to be bedded first. With a utility knife, heat gun and pry bar you can separate the parts at the expense of the paint.



Bob,
Would you use this between planks on lapstrake planking? I was told to use a polysulfide such as Boat Life with a thin strand of cotton. Dont want to hijack the thread, sorry.

[Bob Smalser]

Would you use this between planks on lapstrake planking?

No. Polysulfide or cotton neither. Rivets or clench nails generally have enough give to keep even flatsawn planks from cracking during seasonal movement. Adding anything even slightly binding or adhesive to a joint designed to slide a bit is a quicker pathway to cracks.

[Jay Greer]

Dolphinite used to depend on some carcinogenic compound to make it work well (I can't remember which one, looked it up PCB's) they took that out in the 80's. It's no longer anything like as effective, but one doesn't get cancer from it. Not a bad trade off, I would suggest though that it is still recommended because of it's former (deadly) glory.

Only "Fungicidal Dolfinite" contained the compound you mention. It was creosote.
Jay

[Mrleft8]

Seems to be a bit of contradiction here to what Mr. Bryan says in his article. Where some of you are saying that varnish or paint are better moisture barriers (sealants) than shellac, this is quite the opposite of what he says. (83% protection against water vapor as opposed to 73% for varnish I think.....I don't have it right handy) And the oil impermeability of shellac would tend to make it excell as a sealant under oil based bedding compounds such as Dolphinite. Certainly if the HMC used it as a bonding agent/sealant between layers of double planking, and 50 years later it's still holding up, one would have to infer that they knew what they were doing. Not to say that there aren't modern goops that might hold up just as well.....We'll just have to wait to see.

[Hughman]

One thing Harry didn't mention, is to use dewaxed shellac for a sealer (for a painted surface) if you want the top coat to stick. Dewaxed shellac is available from Highland Hardware.

http://www.highlandwoodworking.com/index.asp?PageAction=VIEWPROD&ProdID=6505

[Jay Greer]

I use a lot of shellac in my finish conservator work. I buy shellac in flake form from Mohawk Finishes. It is, of course, de-waxed. It does however take longer to dissolve than the non de-waxed variety. If you plan to use a lot of shellac, buying dry flakes is much cheaper than buying pre-dissolved shellac in cans. Unlike the premixed stuff, the dry flakes last indefinitely. The premixed stuff has a shelf life of about a year.
Jay