Used shellac for the first time - need advice

[Bob Bowles]

[Steve James]

I just finished the fir base for a new workbench I'm building with commercial Zinsser Bulls Eye Shellac (Clear). I was surprised when I open the can because it looked like milk - a white suspension. I'm not sure if this is wax (I thought clear Shellacs were dewaxed) or if the stuff was spoiled in some way. The manufactured date on the bottom of the can is 8-18-03 so it is pretty fresh stuff. I let a few drops of it dry on the can lid as an experiment and it gave a hard film after drying overnight but VERY cloudy. I tried warming the stuff by putting the closed can in some hot water for a while. No change - none of the suspended solids appeared to dissolve. So I diluted part of it from a 3 lb cut to a 1 lb cut, and filtered it though a coffee filter. Very slow to filter but it gave a nice amber solution which was just slightly cloudy. The filter contained lots of white solids. I use the filtered stuff to finish the base. Put on one coat and let it dry overnight and sanded smooth with 220, then put on two more coats without any additional sanding. The results are quite nice - the wood is slightly darker and has a nice somewhat glossy clear surface. I mainly did this to put a water vapor barrier on the base to minimize wood movement due to humidity change. I don't think I would have gotten this nice appearance if I'd used the stuff out of the can. Is this par for the course with premixed Shellac or did I get some bad stuff? Are the white solids wax or something else?

In the future I plan to mix up my own Shellac and hopefully avoid these problems. Can anyone recommend a good source for dewaxed Shellac flakes?

[The Guy]

[Bay Area Dave]

Steve,

Yes, it will look cloudy. that's the wax. if you leave the can undisturbed for a couple - 3 days and carefully decant it, you basically get dewaxed shellac! OR you can make your own (PITA), OR you can buy Zinnser's Seal Coat, which is dewaxed. A quart is about $8-9 where I buy it at ICP.

dave

Steve James wrote:

[Chris Merrill]

Sounds like wax...IIRC, that's the directions that Flexner gave for dewaxing shellac.

I buy mine from the local Woodcraft store.

[Rob Stokes]

What he said and I HIGHLY recommend using SealCoat (nope, not affiliated, just a believer)

good luck Rob

[Greg]

It sounds as if you have a sanding sealer which has loads of heavy partials that fill the grain and to some extent will obliterate it. if left to stand in a warm room for a week or two it should settle out

Greg

[Silvan]

Weird. I just tried some of that for the first time too. Similarly recent manufacture. It looked rather like caramel in the can. I used it straight up, and I think it turned out OK, though I'm mildly concerned that it took longer than it should have to dry. I'm hoping I just put it on too thick.

My biggest complaint was the smell. It makes poly/mineral spirits smell like sweet candy by comparison. I was totally unprepared for just how noxious those alcohol fumes would be. Probably the "denatured" part of it I guess. I presume it has stuff in the can to make it highly poisonous, so winos don't guzzle it.

[Steve James]

The solvent used for commercial shellac, denatured ethanol, evaporates rapidly to the finish dries quickly but you get a lot of solvent in the air in a short time. Ethanol is much safer from a health standpoint than almost any other organic solvent used in finishes - even the ones that don't have so much smell. The denaturing agent is usually a few percent methanol which is poisonous if ingested and can cause blindness. I don't think breathing small amounts of it is likely to be very hazardous. Some denatured alcohol used to contain benzene - a known human carcinogen. I don't know if it is still used, but I would certainly avoid it. Read the label. I finished my workbench base in the basement and ventilated the room by removing one window and installing a window fan to exhaust air, and opening the window at the far side of the room. The warm weather we've been having on the east coast is am unexpected blessing for this time of year. Since exhausting air from the room creates a slight negative pressure, none of the solvent fumes could be detected in the rest of the house. I wear a mask with cartridge filters when I use any organic solvent finish. You still need good ventilation though or you will overwhelm the activated charcoal in the cartridges. The mask worked well for me when applying the Shellac - I couldn't smell the ethanol at all while I did the application, and afterwards I left the room until the piece was dry and the ventilation had removed all the solvent. Shellac in ethanol dries rapidly so it doesn't take long.

[Andy Dingley]

I've no idea what you use in the USA, but in the UK our "methylated spirit" stinks of pyridine. Horrible stuff, and a really unpleasant thing to work with all day. If you can find strong drinking alcohol, like Everclear (which we don't have in the UK) then it's a lot more pleasant to work with.

Most meths is also dyed purple, which can produce a visible cast in white or some blonde shellac. Undyed isn't that hard to find, but buying unstenched alcohol generally needs a trade account with a chemical supplier.

-- Die Gotterspammerung - Junkmail of the Gods

[Conan the Librarian]

How do you figure that? When I am in the final stages of a project, I always make up a fresh batch. All it takes is a little kitchen scale and a measuring cup (and I'm anal about it compared to some folks). 1 cup of alcohol to 1 ounce of shellac flakes equals a 1 lb. cut. Adjust as necessary to make the amount and cut you want. (I usually use a 1-1/2# cut for brushing.)

Recipe for "instant" shellac: Put your alcohol in a glass jar. Take your flakes and grind them up in a coffeee grinder or wrap them in t-shirt material and pound them to pulverize the flakes. Sprinkle the flakes into the jar and give them a good stir. Close the jar and set it aside. In the meantime, run some hot water in the kitchen sink and fill a bucket partway (just enough to go up the sides of your shellac jar to about even with the shellac level inside). Set your shellac jar in said bucket of hot water and give flakes another stir.

Go back to work on your project and every so often give the shellac a stir and maybe change the water as it cools. (Be careful not to get water into your shellac jar.) When the shellac has dissolved, I like to strain it through cheesecloth to remove any impurities that might be in there (but with Paddy's super-blonde, there are very few), but I'm anal about it.

Total prep time: 10 minutes. Total cooking time: 3-4 hours. Fat content: 0 grams.

Chuck Vance Just say (tmPL) Shellac: It's not just a furniture finish, it's a dessert topping.

[Bay Area Dave]

for a little extra, HD sells a "low odor" mineral spirits. I've never bought any, but if the price of admission isn't too much extra, I think I'll give it a try next time. I hate the smell of the regular stuff. I'd rather smell Zinnser's shellac! :)

dave

Andy D> >

[Bay Area Dave]

:) Well, the way I figured it is by reading books on the preparation method, and on folks' comments here! They have to crush, heat, wait, wait some more, stir, wait, strain, and then they have shellac. OR they can grab a can, give it a few shakes if it's waxed, pop the lid and pour some into a working container. I haven't brewed my own yet, because of all the prep hassle it appears to be. If you find it's not as hard as advertised then I defer to your experience! (and you've still got that

3-4 hours cook time...)

dave

C>

[Chris Merrill]

If you need it "right now" then it is not convenient.

When I'm working on a medium-large project, I mix up a batch when I'm starting the final assembly. It takes about 3 minutes to measure & mix the alcohol and flakes. Then I shake it 2-3 times per day and it's ready in a few days.

If you shake it every 5 minutes, it should be dissolved in about an hour. Note: I've never bothered to grind the flakes into powder -- it _may_ be possible to get it ready even quicker, that way.

YMMV

[Chris Merrill]

Must be a smell that is specific to different people. I mix my shellac with denatured alcohol (from HD) and strongly prefer the smell over mineral spirits. It brings to mind fond memories from college :>

[Andy Dingley]

Mineral spirits ? If that's what we call "white spirit" then it's no use with shellac at all.

Shellac needs methylated spirits (mainly ethanol with some methanol, and the colour and stench) or some people favour isopropanol (isopropyl alcohol).

-- Die Gotterspammerung - Junkmail of the Gods

[Bay Area Dave]

Andy, I'm talking about "paint thinner". Mineral spirits = paint thinner. It's used for poly; not shellac. Denatured alcohol for shellac, as you mentioned several types.

dave

Andy D> >

[Bay Area Dave]

How long will the stuff last after being mixed by the user? When I use Zinnser, it should last longer in the can then it takes me to use it up. I buy by the gallon now, after going through a few quarts. The dewaxed I picked up recently I got in a quart as I don't think I need too much of that kind.

dave

Chris Merrill wrote:

[Scott Cramer]

On 05 Nov 2003, Bay Area Dave spake unto rec.woodworking:

Gesundheit.

[B a r r y B u r k e J r .]

I LOVE the smell of shellac!

Barry