I am using Zinsser Bulls Eye Shellac to finish some pine moulding n a new room in my home. I have cut the shellac from a 3-lb cut to 1-lb cut according to the directions on the can. The shellac is being applied with a 2 inch nylon brush. My problem is streaking. Before I can brush out the shellac, it seems to be nearly dry. The boards end up with darker streaks. What have I done incorrectly? Thanks, Melvin
Discussion Forum
Get It All!
UNLIMITED Membership is like taking a master class in woodworking for less than $10 a month.
Start Your Free TrialCategories
Discussion Forum
Digital Plans Library
Member exclusive! – Plans for everyone – from beginners to experts – right at your fingertips.
Highlights
-
Shape Your Skills
when you sign up for our emails
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. -
Shop Talk Live Podcast -
Our favorite articles and videos -
E-Learning Courses from Fine Woodworking
-
-
Replies
1 lb. cut is very light, usually best reserved just for wash coats. Because it is almost all alcohol it dries quickly. Even with a bit heavier cut, you never have time to apply shellac and then brush it out. It's just a process of making a single pass with the brush, moving only in one direction. You should be reasonably neat about it, but not meticulously so.
You indicated you were using a nylon brush. Nylon comes in a wide variety. The kind you want for applying shellac is the very, very fine kind sold as artists watercolor wash brushes, often under the brand Taklon Gold. This is so fine that the one pass with the brush starts level with no brush marks to have to flow out. You can see overlaps--perhaps looking like streaks, but they shouldn't be very prominent and will disappear as you add more coats of the shellac just taking care not to overlap in the same place each time. Similarly, if you miss a spot just be sure you cover it on the next coat--you won't have time to go back and try to fill in without making a mess.
I use a soft natural hair brush (Purdy white China). You cannot brush out Shellac like Poly or oil/varnish. Use a large brush to lay down the Shellac as fast as possible, take one, maybe two, strokes and dip again. You MUST maintain a wet edge. On a large table this can be difficult so plan ahead and work quick. Don't try to be too neat but avoid errant drips on already brushed areas. Avoid the temptation to go back and brush out the previous passes, it will not help. There will be brush marks no matter what. If your technique is good you should get a surface about as good as you can with latex paint straight from the can. A one or one and a half pound cut is good. I find that 2 pound cut takes too long to dry, but then I also lay it down pretty thick. After 1 to 3 hours it will harden enough that you can level off the brush marks with 200 or 150 grit sand paper. Press your fingernail into the surface, if it dosent leave an impression or feel soft it is hard enough. Use liberal amounts of Mineral Spirits to keep the paper from clogging, though it will still clog up fast. Make sure all the Mineral Spirits has dried before applying the next coat. One secret I have learned is that as soon as the surface is not tacky you can rub the surface with #O steel wool to knock down the "off the brush sheen" and it will harden a lot faster.
the great thing about brushing Shellac is that no matter how bad it looks off the brush it can easily be leveled and polished to perfection.
Edit... Zinzer's "dewaxed" Shellac still has a lot of wax in it. If you pour it into a glass jar the wax settles to the bottom in about an hour or two. Pour the Shellac back into the can leaving the wax in the jar. The wax makes the finish harden a lot slower and results in a softer finished surface.
Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
Edited 7/17/2007 12:52 am ET by mudman
>> Zinzer's "dewaxed" Shellac still has a lot of wax in it.You might want to follow this link to the Zinsser site. Their "Sealcoat" is a 100% dewaxed shellac.http://www.zinsser.com/product_detail.asp?ProductID=72Howie.........
After spraying, brushing, and french polishing gallons (no exageration) of the zinzer stuff. I assure you that there is a wax like substance that settles to the bottom of their dewaxed Shellac. Maybe it is not wax, but it looks and behaves like wax. It could be some odd wax like additive...... but I am pretty sure it is wax. I do like it, and will continue to use it for small quick jobs. Removing that wax like stuff at the bottom of the can seems to help.Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
Howard,
After spouting off I checked the link you posted and see that you are talking about the primer/sealer product. I haven't used this product, my experience is with their Bullseye Shellac finish that is sold as a wood finish. The sealer probably is wax free, but I dont think that they intend that stuff to be used as a top coat because it is meant to dry and harden very fast, then be stained or polyied over.
Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
Mike, the Zinsser SealCoat is a 2# cut blond dewaxed shellac pure and simple. They chose to call it a sanding sealer to take advantage of its use for that purpose. It is perfectly usable as a standalone shellac finish. Any shellac can be used as a sanding sealer as well as a standalone finish. The SealCoat is marketed to those who want to use a shellac as a first coat sealer under a polyurethane varnish or a waterborne finish. Those two finishes will have poor adhesion to standard wax containing shellac. That's the reason most poly varnishes carry the label admonition to not use over shellac.As far as the other Zinsser shellacs, they do contain wax. However, their aerosol shaker can shellac is totally dewaxed as wax will clog the spray nozzle.Howie.........
Just to add, Seal Coat doesn't dry any faster than 2 lb. cut shellac made by diluting the wax containing Amber. It has no additives--the resin is 100% shellac. Dewaxed shellac is a bit harder and quite a bit more water resistant than shellac with wax--considerably better as a top coat. (I also like to point out that the Clear is considerably worse as a top coat because of the effects of being chemically bleached.)
I also looked at the bullseye can yesterday, it actually dosen't say dewaxed anywhare on it! I though it was. Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
Right. I have used a lot of Zinsser. As far as I know, the only de-waxed product they sell is Seal Coat, which is 100% de-waxed. It is a lovely product that works well and has a long shelf life.Joe
Simchart,
Might I suggest you abandon the use of shellac in this instance? Shellac is really quite challenging to apply with a brush let alone brushing it on moulding. Maybe a waterborne finish if you want something that will dry fast or just a simple poly. Either would work better in your application.
As the others have stated your viscosity is to thin. A 2# cut would be better in this application since you have two problems to overcome. First is the rapid dry time of shellac in general and the second is the absorption of the wood, both are difficult to overcome with a brush, but not impossible.
You also might consider continuing to apply the 1# as a sealer/washcoat this will solve the absorption problem and once applied you will need to lightly sand it. I would than apply a 2# cut as a finish coat. Try to remember that as soon as you apply the top coat it will reactivate the shellac below it so you would need to move quickly in one direction with no more than a second swipe of the brush.
Good luck, it’s not that easy.
http://www.josephfusco.org
The "wood absorbtion" is not an issue. After the first coat there is no absorbtion. And while oil/varnish products are easier to get a nice finish off the brush for the experienced, they cannot be leveled to perfection the way Shellac can. Really you could apply Shellac with a trowell and used paint roller and still achive absolute perfection once it is leveled.
Certaintly the actual brushing is a challenge, but dont stress over it.Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
It may be my imagination, but it seems that Behkol evaporates a little slower than regular denatured. There are also shellac retarders that slow it down a little bit. The best thing I think is to keep saying to yourself - "I'll fix that on the next coat". You really can't "work" shellac like you do varnish or oils. You have to brush it on and walk away.
Melvin, have you thought about padding the shellac on rather than brushing?? Not a French polish, but the "airplane landing and taking off" approach described by Jeff Jewitt in a couple of articles.
I agree with those who say a 1# cut is too dilute.
Reading all of the earlier posts on the Zinseer shellac, makes me wonder?? Why use shellac from a can? It seems like you can avoid many of the doubts expressed in the discussion by mixing your own from flakes. I like knowing how old the shellac really is. I just can't help wonder how long has this can really been sitting before I use it. After I use the shellac many times I have to toss it due to age. With mixing your own, you have fresh amounts, just what you need and no can on the way to the landfill when you don't use all of it.
And de-wax it?Gretchen
Gretchen, you can buy de-waxed flakes from more than one source.
Joe
Good to know. I thought they all had a bit of wax at least. Thanks.Gretchen
Technically all Shellac will have trace amounts of wax. If after two days of sitting in a jar there is no wax settled in the bottom, that is pretty well dewaxed.Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
danmart,
I use gallons of shellac a week.. never had an issue with old shellac..
Even shellac that I mixed up at the 2# rate and it took forever to dry when I reduced that same can to a 1# cut it dried in the normal time.
Look at the makeup of the chemical chain of alcohol.. if you look at the light ends of the chain you see plenty of room for instability. It's extremely easy to have alcohol sit around and loose the light ends.. the cap doesn't even have to be loose enough for you to smell it and some of the light ends can escape..
In the heavier cuts where alcohol makes a smaller portion of the mix it would be very easy to use alcohol that had been mishandled anywhere along the chain from manufacturer thru the distributor and dealer.. some of the light ends had escaped and the result is shellac that causes problems. we never blame the alcohol. It's always the shellac,
Except I can remove shellac off something that may be 50 or 100 years old using alcohol and the rag I will use will dry stiff as a board quickly.. so why would 100 year old shellac flakes dry properly and 6 month old flakes cause a problem?
I contend that the issue is the alcohol not the flakes!
frenchy, I think you are a better finisher than a chemist. Shellac flakes change their chemistry. Not alcohol. Esterization eventually makes them unsuitable as a good finish, if they get old, especially if they are not kept cold and if they come in contact with much atmospheric water. The fact that an existing, very old shellac finish film can be removed from a wood surface by rubbing with a rag wet with alcohol does not say anything about the qualities of old shellac, other than it's possible to get it off the wood with enough alcohol, if you are persistent. And the fact that the rag dries, losing all its volatile alcohol to evaporation, leaving "stiff" shellac residue in the weave of the cloth, also tells nothing about that dry substance's ability to form a fine finish on furniture, ever again.
To add to what you have said, as I understand it, shellac can deteriorate in several ways. The flakes polymerize, particularly if warm and humid conditions prevail, reducing soluability and making them unusable. I'm not sure that in the short term of a few years the chemical process is really mostly esterification or mostly some other process. Certainly over longer times esterfication of dry shellac is an issue, as can be seen in problems conserving old shellac records.
I've always thought of the esterification process as primary change that is accelerated when shellac is mixed with alcohol. Thus, liquid mixed orange shellac has a much shorter shelf life than orange shellac flakes. This is the chemistry of the solution, not any defect in the alcohol, and would occur with the purest anhydrous ethanol as far as I know.
(Bleached shellac however has an extremely short shelf life in dry form, which is why you never see it that way in finishing materials.)
Edited 7/22/2007 9:56 pm ET by SteveSchoene
Thanks Steve.
BTW, I have had bleached shellac flakes, after initial use of a small quantity, then stored in air-tight bags, with a small bag of (initially) dry desicant become unuseable in 6 months. I always intend to try vacuum sealing and storage in a freezer, but never get around to doing it.
Edited 7/23/2007 9:09 am ET by Rich14
I have never seen dry bleached shellac available in small quantities from any source. Plenty of Super Blonde, or Ultra Blonde, etc. flakes but they are "decolorized" not bleached. My understanding was that dry bleached shellac solidifies into a solid block within a matter of days. Bleached shellac has a longer shelf life in liquid form than in dry.
Steve,
I didn't know that. I simply assumed that the blonde and ultra-blonde flakes I have been buying were bleached. I've never heard the distinction between "decolorized" and bleached.
What is the decolorizing process?
According to Zinsser's Story of Shellac decolorization is done by filtering through activated carbon. Of course, different grades of the initial natural shellac come with different amounts of dye depending on things like season harvested and location.
But the bleaching process is quite a bit different. The seedlac is dissolved in a water solution of sodium carbonate (washing soda or soda ash.) The bleaching part of the process is done with the addition of sodium hypochlorite (chlorine bleach). I have no idea what the concentration is--whether it is more like household bleach or like pool chlorination bleach. The bleached shellac is then precipitated by addition of sulfuric acid. The powder is then filtered, washed, and dried. It is then used quickly to make liquid products to avoid the shelf life problems.
Yeah, I'm aware of those processes.
But I didn't think that blonde or ultra blonde came from carbon filtering. I was pretty sure those grades were the result of bleaching.
Steve:I have some flakes that are more than 4 years old and are quite usable. Some are light amber, and others are pale blond. They have been kept in sealed zip-lock bags at normal US room temperatures of 75 degrees or less (depending on season. I just mixed some up a few weeks ago with fine results.Joe
You are correct. Working from flake is better. The flake I buy is dewaxed and very nice. It keeps forever in the flake form (once mixed it is wise to ditch it after a year). Shellac from the flake also hardens faster.Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
I would go with flakes when I wanted a specific color of shellac, but for washcoats and such, the cans are easy. I've used Zinnser shellac that was several months past its expiration date, and it's worked fine. Their shellac, specifically, lasts much longer than any other -- some kind of process they use, don't have time to check at the moment.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
This forum post is now archived. Commenting has been disabled