I am preparing shellac from flakes for the first time. I have a 1/2 pound of garnet flakes and want to end up with a 1 lb. cut.
Per instruction, I am soaking the flakes in half of the final amount of alcohol (quart). It has been 2 days. I am ending up with an inch or so of goo at the bottom of my container. I’ve stirred it, shaken it, and left it upside down.
Should I: Have more patience? Add more denatured alcohol? Pour out the liquid into another container and mix new alcohol with the goo?
Something else?
Thanks, John
Replies
John,
Patience. Sometimes its taken me 5 or more days. It helps if you start with smaller chips...
My shellac flakes are usually more of a shellac brick because they completely fuse together. It takes a hammer and screw driver to break them into chunks. I finally got an old fashioned food grinder and now grind them into very small pieces before mixing them with alcohol. It speeds up the process tremendously.
Leave it for a day then strain it.
John,
If the temperature of the shellac/alcohol mixture is cold the flakes will take much longer to dissolve. I can dissolve 1/2 pound of flakes in a quart jar in a few hours if I run hot water in the sink and put the jar in it.
How old is the shellac and where did you get it? Even in the flake form shellac has a shelf life depending on how it is stored. If stored in a cool, dry place (read refrigerator) their shelf life is probably longer than yours. If they are kept where it gets hot or they are allowed to get damp they can be ruined pretty fast. If they get turned into a brick they have either gotten too hot or have been exposed to too much moisture.
I don't see any reason for mixing the flake in only half the desired alcohol. If I am looking to mix a pint, I'll mix a pint. If I want a quart, I'll mix a quart.
Try the hot water bath. If that doesn't work I would test the shellac before you use it.
Rob
Thanks. I just received it from Shellac.net. I used their instructions about the 1/2 amount mixing. I'll try the hot water.John
A thrift store Mr. Coffee grinder does a first class job of reducing the flakes to a fast dissolving powder.
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Men will never be free until the last king is strangled with the entrails of the last priest.~ Denis Diderot
John- Just a thought, but you'd really need to be re-finishing a gym floor to use that much shellac at one time. You may know this, but once mixed with alcohol, shellac has a shelf life of about a month (perhaps more if kept cool).
You've given us the shellac amount, but you didn't say how much alcohol - you've probably got the amount calculated correctly, but it helps to be sure. If you've got 1/2 lb. of shellac, it's 1/2 gallon (or 2 quarts) of alcohol to give you a 1 lb. cut. That means a separately measured 1/2 gallon - not filling the container with shellac already in it to the 1/2 gallon mark.
Warming the container will help greatly, but be cautious. Heating a sealed container of alcohol in a bath of hot or warm tap water can easily pressurize the container beyond its limits - besides being really exciting (ka-boom), it'll make a huge mess and result in a large vapor cloud of ethanol - which is potentially explosive given an ignition source.
Regarding containers, there is an old thread started by me describing leaking cans when used for shellac. Others also encountered the problem. Do not use empty cans from HD, etc. Stick with glass or some other seamless material not effected by alcohol.
Put on some Led Zeppelin and dance that jar around the shop for an hour...
I have had good luck shaking the jar for 1/2 an hour. I usually grind the flakes in a (cleaned out) coffee grinder. Shellac is approved for food use, (ever eat M&Ms?). So you can use the wife's, but you probably don't want to tell her...
Any way, I mix all the alcohol and shellac at once. I think a little heat might do you good. Put it in the oven with just the light on. Don't forget it's there or you'll burn the house down.
Lot's of good info on this thread. Especially: check it before you apply it. That might save your project.
Best of luck, post some pictures of your success.
Fred
Are you now going to assert that leaving the light on in your oven is a leading cause of house fires?
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Men will never be free until the last king is strangled with the entrails of the last priest.~ Denis Diderot
Editor's Note: Deleted personal attack and vulgar language.
Editor's Note: Deleted personal attack and vulgar language.
Well, you have a point greenie. But if you wear a hat no one will know.
John,
Just to bring this thread back On Topic.
Sorry for some bad news. Your shellac is bad. It happens all the time. Just because it is a new batch to you, doesn't mean it is fresh.
I always mix my shellac from flakes. I use a coffee grinder (used only for this purpose) to grind the flakes into a fine powder. The powder dissolves in about 15 minutes if I keep the solution constantly swirling. This makes it easy to quickly mix up a new batch when I need, and not more than I'm going to use at a time.
But I've had shellac that would not dissolve even after being ground. Unground, the flakes should dissolve in 24 hours, 48 absolute max. You should not have to warm the alcohol above normal room temperature. Some people recommend filtering out any slight amount of residue after trying to dissolve for a day or two,
Don't accept such advice or shellac that results in that situation. Fresh shellac dissolves very readily and leaves absolutely no residue, even if mixed to a high concentration. If there is a gummy residue in liquid form, the shellac will never properly harden, even if you use the clear portion and discard the gummy residue.
Shellac flakes that don't dissolve readily have "expired." They have been exposed to humidity and heat for too long in storage and should be thrown out. Like a shellac solution that has gotten too old, they undergo chemical changes (esterification) that make them unusable. I'd demand that your batch be replaced.
Unless you are preparing a very large batch, there is no good reason for using 1/2 the amount of alcohol to dissolve your shellac. It simply results in 1/2 the volume at twice the concentration that you need. Just weigh out or measure the amount of flakes you need and use the total amount of alcohol right from the beginning for any reasonably-sized quantity.
Rich
What are the characteristics of shellac that is bad? What signs should I look for? I did get it to dissolve and have applied it to a prototype that I'm working on. Just testing different combinations of finishing products for now.Thanks for your interest, John
John,"What are the characteristics of shellac that is bad? What signs should I look for?"As I said, it should dissolve easily, usually in 24 hours, just sitting over night in alcohol. Nothing more. OK, no more than 48 hrs. Extraordinary measures such as warming the alcohol should not be needed. If ground into a powder, it will dissolve in no more than 15-30 minutes. There should be NO gummy mass swirling at the bottom after 24-48 hours.You got yours to dissolve. How?Apply it to a scrap piece that has been sanded through the grits to 220. It should be perfectly hard and dry at room temperature (68-70 degrees) in 1/2 to 1 hour and such a thin layer should sand easily at that point with 320 grit to a fine, dry powder. If not, don't use it.Rich
John - Rich's given you good advice, with a couple of exceptions. If you've just poured the alcohol on top of shellac flakes, then you can indeed get a gummy layer on the bottom that's not a problem. It's just softened shellac flakes that have melted into a gel layer. If you then mix this gooey layer up into the alcohol by stirring it several times over the course of a couple of hours, it should also dissolve.
However, regarding Rich's advice - if you still see a gummy layer of residue on the bottom of the container even after throughly mixing and waiting about a day, you probably do have shellac that's gone bad. Rich's test is a good one - if a drop of it does not harden within about 30 minutes, it's probably no good. Throw it out and get a new batch of flakes.
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