Shellac and BLO Finishing questions

[David Dalzell]

I have two (novice) questions:
First - Are waxed and dewaxed shellacs compatible? That is will they adhere well to each other?

Second - If I put down an initial coat of BLO and then follow this with either waxed or dewaxed shellac will the BLO and Shellac adhere? Maybe this is two questions here.

I am experimenting with a finish for walnut. I plan on making up a number of test panels with different shellacs and possibly BLO (as a base coat). I don't want to waste time and materials where there are incompatibilities.

I have dewaxed Zinnzer Seal Coat, dewaxed orange flakes, and dewaxed garnet flakes. I also have waxed Bysakhi Button (a deep brown red). I want to bring out the grain and have a dark rich color.

Thanks for any help and advise.

[glenn bradley]

Dewaxed shellac sticks to just about everything and just about everything sticks to it. This is why it is used as a vapor barrier, primer additive, seal coat, etc. Generally I read that waxed shellac can have issues when followed by some top coats although there is a loud minority that poo-poo this out of hand. I just use dewaxed and have not had trouble. In fact I use it when there is a question as to compatibility between products.

[Neal Clayton]

if you don't plan on putting anything else over the waxed (except more wax) it will be fine. shellac sticks to anything, including other waxed shellac. so yes it will stick to the blo film, and it will stick to itself.

[Scott Holmes]

The only time de-waxed is a must is under polyurethane varnish and water-borne finishes.

Non-Poly varnishes adhere just fine to shellac, de-waxed or not.

[David Dalzell]

Well thanks for the help and advise. It seems as though I can experiment to my heart's content. I don't plan on putting on top of the shellac except a final buffing with wax.

[Jim Becker]

Shellac is very forgiving...any shellac will stick to any shellac, waxy or not waxy. I tend to only use de-waxed shellac just to keep things simple. While I do use shellac as "the" finish from time to time, I most often use it as a barrier coat under water borne finishes.

BTW, while most of the time we typically wait a day or so between applying BLO and overcoating it with shellac...you don't have to wait. Once the oil has soaked in and you've wiped off any excess, you can proceed with shellac "really soon" if you need to. There was an article about this awhile back in Fine Woodworking, I believe, and I've taken advantage of this from time to time when, well...time...was short.

[Brett Bobo]

Jim,
I was reading through an article by Jeff Jewitt last night on padding shellace and he also mentions that shellac can be used approximatley five minutes after applying the BLO. Conversely, I've seen a few comments on the forum stating that BLO must dry for at least five days before applying the next coat, such as shellac, for fear of it bubbling up. Based on this concern and to be safe since time isn't an issue, I'm actually on day number five of waiting for the BLO to dry on a cherry bed that I'm finishing. Have you had any issues with the finish over time by applying shellac immediately after applying the BLO and wiping it dry? Is the dry time of BLO an issue with any particular finish?

Thanks for the help!
Brett

[Jeff Hamilton Jr.]

Brett,

I've actually used Jeff Jewitt's method from the FWW article on a small Ash bookcase I made for my son. Sooo, shellac (dewaxed) was my final finish. I did topcoat that with Ren Wax and, 2 years later with a 2 yr-old boy now 4 and all the abuse that goes along with it, it shows almost no wear.

I didn't wait ANY time between the BLO and the application of shellac other than to wipe it down to where it felt dry. Probably a few minutes at best.

In my limited experience (I've finished with lacquer, poly, friction finishes on the lathe and shellac), this is the nicest finish I've done. It feels GREAT when its rubbed out.

Good luck.

[Jim Becker]

Brett, I've done the accelerated finish method many times at this point...BLO followed by spraying (or brushing) de-waxed shellac about an hour later (only because I go for a snack LOL) and then spraying my water borne finish about an hour after that. "Same day" finishing when I feel the need. In most cases, I'll use the oil late in a day and then proceed with the rest the next day simply because that works out best time-wise for me, but I'm not worried in the least about issues between the BLO and the shellac.

That said, the species being worked will have some consideration in the decision. I generally work with close-grained woods like cherry and poplar, although some air dried black walnut also figures into the mix. With cherry and similar, there is little issue with oil "bubbling up" because there are no large pores for the oil to collect in. Someone working in oak or ash may find the need to wait a little longer and wipe off several times over a day or three.

[Scott Holmes]

I too, have "rushed it" with no adverse reactions. As Jim said I would not rush the shellac seal coat over porous woods like red oak or ash. I usually give BLO a day or overnight to dry. Most time I wipe it on and wipe it off within a few minutes I don't flood it on.

[John Hollaway]

Jim mentioned spraying shellac, and that raises a question. I often spray lacquer (Deft Clear Wood finish mostly, with my Fuji Q4) but have never sprayed shellac. Are shellac/alcohol vapors considered to be more explosive or less explosive that lacquer vapors? Thanks.

[Chris Padilla]

John,

I spray shellac all the time and don't find it too bad (I do not use a spray booth...do not have one). I just leave the garage door opened and it works for me. I would hazard a guess that the "shellac vapors" are less explosive than the "lacquer vapors" or at least the "lacquer vapors" bother me a lot more than the "shellac vapors."

[Kent A Bathurst]

Jim,
I was reading through an article by Jeff Jewitt last night on padding shellace and he also mentions that shellac can be used approximatley five minutes after applying the BLO.

Without taking the time to read the article or open up my book, IIRC, the BLO is intended only to pop the grain, and I think that Jeff's method is to use enough BLO just to get a damp spot on a rag, and rub it in - only using just barely enough to put down a very light film. I don't think there is much of anything there to "bubble up". Hope not, anyway - been doing that a long time :D. Works especially nice on cherry, with rubbed-out shellac as the only finish on top of the BLO. Oh - also did that on QS sycamore panels in a frame-and-panel blanket chest. Nice grain in that stuff.

[Scott Holmes]

Lacquer thinner vapor is a lot stronger than denatured alcohol (DNA) vapor.

Not sure if it more explosive; but I would guess that it is more than explosive DNA.

I've not experienced it, however, the DNA can make you drunk. I've heard from a reliable source that it is the worst hangover imaginable.

[Mark Blatter]

"I spray shellac all the time and don't find it too bad (I do not use a spray booth...do not have one). "

I tried spraying shellac twice, using a pretty high end sprayer, in a booth and it came out terrible. What pound shellac do you use when you spray? I found that the shellac dries so quickly that it doesn't have time to spread out into a nice even finish. Any more I only use a high quality brush to put it on, but it is my favorite seal coat.

[Steve Schoene]

Alcohol vapor can be a bit insiduous. It would be heavier than air, flowing unnoticed along floors, and if you have high enough concentration might flash back with an almost invisible blue flame if ignited. So ventilation is still in order.

[Jim Becker]

"I spray shellac all the time and don't find it too bad (I do not use a spray booth...do not have one). "

I tried spraying shellac twice, using a pretty high end sprayer, in a booth and it came out terrible. What pound shellac do you use when you spray? I found that the shellac dries so quickly that it doesn't have time to spread out into a nice even finish. Any more I only use a high quality brush to put it on, but it is my favorite seal coat.

Mark, I spray Zinsser SealCoat dewaxed shellac straight from the container, strained of course. There isn't and shouldn't be any "spreading out" issue because shellac is supposed to go on as the thinnest possible application. In fact, you do not want shellac to "build" up like a varnish...it can and will crack and cause other issues, especially if you will be further coating the workpiece with other finish materials.

[Tony Bilello]

John,

I spray shellac all the time and don't find it too bad .... I would hazard a guess that the "shellac vapors" are less explosive than the "lacquer vapors" ......."

According to MDSD sheets Denatured Alcohol and Pre-Cat lacquer have the same safety ratings on Flamability and Health.
Reactivity Ratings - both = 0
Flamabilty Rating - both = 3
Health Rating - both = 2

These ratings range from 0 to 4 with o being best and 4 being worst.

I couldnt find any shellac MSDS sheets, but I didn't look real hard. All I can say is don't underestimate alcohol.

[Chris Fournier]

Well let's see, they have alcohol based top fuel dragsters that rip the atmosphere and send cars down the qaurter mile in seconds. I think that the alcohol vapours just might be volatile.

[paul cottingham]

I put waxed amber shellac over Tried and True danish oil without trouble. makes a great finish.