Wood Basher Posted February 8, 2017 Report Share Posted February 8, 2017 I read a lot & watched a ton of videos before making my first attempt at French polishing (which is also my first attempt at any decent finish). One thing I learnt was that mixed shellac has a limited shelf life. Now I didn't mix my shellac from flakes, I bought ready-mixed polish in a tin. I can find no date on the tin, so how would I know if the contents were too old? One thing I did notice is that I was getting some dark discoloration and I don't know why. It was like a grime mark on the table top I was polishing. I was able to remove it by some vigorous scrubbing with alcohol. Could this be a problem with old shellac? Or perhaps I didn't shake the can enough before use? Or did I do something else wrong? Quote Link to comment Share on other sites More sharing options...
gee-dub Posted February 8, 2017 Report Share Posted February 8, 2017 Brand and product info would help. Zinsser Seal Coat has a 3 year shelf life if properly stored. The alcohol carrier has water in it so I decant mine into plastic or glass containers and have accidentally left stuff for at least three years and still had a usable product. For those who have found a shorter lifespan I should state that I live where the temp and humidity swings are mild. In case you have a Zinsser product here's something from them in an email (I think the code may have changed since Rustoleum got them (?): "Here is how to read the stamp. The first letter “S” identifies the plant that packaged the product. In the case of the two cans shown, it was Somerset, NJ. The first number is the last digit in the year the shellac was packaged. The second number is the month. For October, November and December the first letter is used instead of a number: “O,” “N,” or “D.” The third and forth numbers provide the day within that month. The fifth number or letter indicates the “run” on that date." I mark the older stuff and use it on jigs and fixtures or the insides of carcasses. Quote Link to comment Share on other sites More sharing options...
Gilgaron Posted February 8, 2017 Report Share Posted February 8, 2017 Get a piece of glass, drop a drop of the shellac on the glass. Wait 15 minutes. It should be hard. If it is gummy then it is no good. A really bulbous drop might take longer, I suppose, but in any case if after overnight your shellac is sticky then you can get rid of it. I just pour it in some sawdust, let the alcohol evaporate, and throw it in the trash. If it hardens then it is ok, and the discoloration is likely just due to not being resuspended evenly. Quote Link to comment Share on other sites More sharing options...
Wood Basher Posted February 8, 2017 Author Report Share Posted February 8, 2017 4 hours ago, gee-dub said: Brand and product info would help. The brand is Liberon. Giving the actual product details won't help because it is not in English, but a rough translation is just French shellac polish. 4 hours ago, Gilgaron said: Get a piece of glass, drop a drop of the shellac on the glass. Wait 15 minutes. It should be hard. If it is gummy then it is no good. Thanks for the info. I did that and the polish had hardened when I tested after a half hour or so. Quote Link to comment Share on other sites More sharing options...
AceHoleInOne Posted February 8, 2017 Report Share Posted February 8, 2017 Shellac is still good even if old. Just dries slower and more moisture prone (water-rings) good on items needing less protection. Fresh shellac dries faster so will be nice and hard won't shrink back causing finishing issues in a schedule. Seal-coat has resin or something to help with shelf life. If stored properly can last longer than 5 years. Shellac in higher pound cuts last longer. Thinning shellac reduces life. -Ace- Quote Link to comment Share on other sites More sharing options...
Gilgaron Posted February 9, 2017 Report Share Posted February 9, 2017 Well if it hardened then it ought to be fine. Does it have visible chunks in it? Sometimes I accidentally contaminate my shellac with sawdust or wood bits, but you can filter it through a cotton shirt or cloth. Quote Link to comment Share on other sites More sharing options...
Wood Basher Posted February 9, 2017 Author Report Share Posted February 9, 2017 No, no visible chunks and no solid bits at all. The discoloration is noticeable because this is a light shellac on a light wood (birch). Perhaps the problem would not be seen on a darker wood. Yesterday I bought another tin of the exact same product but from a different store. This tin has the same issue so perhaps it is something I am doing wrong. Not a show stopper as I can get rid of the marks, but certainly an annoyance. Quote Link to comment Share on other sites More sharing options...
AceHoleInOne Posted February 9, 2017 Report Share Posted February 9, 2017 17 minutes ago, Wood Basher said: No, no visible chunks and no solid bits at all. The discoloration is noticeable because this is a light shellac on a light wood (birch). Perhaps the problem would not be seen on a darker wood. Yesterday I bought another tin of the exact same product but from a different store. This tin has the same issue so perhaps it is something I am doing wrong. Not a show stopper as I can get rid of the marks, but certainly an annoyance. Can you post a picture of your issue? -Ace- Quote Link to comment Share on other sites More sharing options...
Wood Basher Posted February 24, 2017 Author Report Share Posted February 24, 2017 Getting a photo to show the problem proved to be more difficult than I would have thought. The attached picture is the best I can do. The darker smudge in the center of the image is just a "stain" of some kind - it does not exist in the wood itself. I can get rid of it by rubbing with alcohol, or shellac and alcohol, but this messes up the finish and puts me back a few steps in the polishing process. Quote Link to comment Share on other sites More sharing options...
gee-dub Posted February 24, 2017 Report Share Posted February 24, 2017 I cannot tell what the material is from the picture but, many woods like maple and cherry are "blotch prone". The nature of the wood absorbs finish to a differing degree in different areas. A common fix for this is some form of sealer often a very thin wash of dewaxed shellac. There are also commercial products available. The challenge here is that you have already applied some finish and the deep absorption has taken place. The fact that you can remove enough finish by scrubbing with DNA to get back to the look you want is encouraging. This would make me think that a very thin cut of shellac could still be used as a pre-conditioner. Any places that went too dark could be corrected in the manner you have already used. After the area is sealed, other light coats of shellac padded on may not aggravate those trouble spots. You may notice their return as you pad over them but, hold judgment for an hour and then look again. This bring up a very important part of applying shellac; do not go back and try to fix things during application. This generally only makes things worse or causes other problems as the finish dries so quickly. Apply one thin coat and let dry 30 to 60 minutes. Then fix any areas you missed or went heavy on. Then apply the next thin coat. I do not attempt heavy build coats when applying shellac. Once I have the build I need to do the polishing step I wait 24 hours and then move on to polishing. There are many methods described by a lot of folks who know more about his than I. This is just the method that I have morphed into based on success for me. Quote Link to comment Share on other sites More sharing options...
AceHoleInOne Posted February 24, 2017 Report Share Posted February 24, 2017 Can you use some 600 sand paper and wipe that area to even the color? I would rather see you do that then using DNA. Looks like a blotch going or your getting to much build of the shellac in that area. -Ace- Quote Link to comment Share on other sites More sharing options...
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