How to store Shellac long term.

[Tom Baugues]

I’ve been using clear shellac over the past 10 years. Only comes in quart cans. I’ve had two cans now rust through before I can use up the shellac. At $15 a can I would like to find a better way to store it. I usually just store it out in my shop which can go several months without heat in the winter months. Would simply storing this in the house prevent this? I have 20 year old cans of stain that don’t have rust in them so why does my shellac rust?

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[Darren Wright]

My last gallon can sprung a leak, so transferred it to several mason jars, and stored fine in them. I just used the last of it up on the motorcycle rocker I've been working on after about 3 years of being stored in them.

Edit: mine was the de-waxed version (sealer), I think the milky part of yours is probably wax.

 

[Rennie Heuer]

My two cents with the reminder that you get what you pay for - Moving it inside COULD help as the rust MIGHT be a product of condensation. To echo Darrens comment, I've had good luck with storing it in mason jars. You might also look at the collapsible bottles photographers use for storing developer fluids. I go through a couple of quarts a year so I've not dealt with very long term storage problems though I did think I was being smart one day and purchase a new 1 qt paint can from Menards to store some garnet shellac I wanted to mix from flakes. It started to leak in just over a month.

 

[Tom Baugues]

Rennie, I looked at the new plastic “empty” paint containers also but thought I would ask here first.


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[Rennie Heuer]

Rennie, I looked at the new plastic “empty” paint containers also but thought I would ask here first.


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The one I used was metal - and it leaked. Haven't seen the plastic ones. Might be worth a shot.

One more observation, stains have a different solvent base (Mineral spirits) than shellac (alcohol) which might account for shelf life.

 

[glenn bradley]

There is a small amount of water in the solvent. Stored air-tight over time (temps up, temps down, temps up, etc.) puts that water to work. Even the lined cans seem to fail. I open new cans and decant into, in order of preference:
- Accordion plastic containers that Lee Valley used to sell. These allow you to minimize the air space.
BTW, I have stored shellac in these plastic containers for years without issue . . . not the same shellac for years . . . but various shellac for years
- Mason jars with plastic lids of reducing sizes to control the air space. Lids from Lee Valley or other canning suppliers fit all my jars the jars just get shorter; cheap insurance in my book.
- Mason jars of reducing sizes to control the air space.



I cleverly used the bananas for scale.

The first can I had leak was reported to Zinsser via their website. They sent me a coupon for a replacement good at any Zinsser dealer.

 

[fred hargis]

It's not uncommon. After I had one leak and make a mess I started putting the cans in plastic bags to at least contain the leakage. It is a chemical reaction (the rusting) so refrigeration might help, but the alternate containers is a lot easier to deal with. My preference would be glass, that's what I use for the flake shellac I mix.

 

[Charles Lent]

Shellac is a mixture that contains large amounts of alcohol. Humidity from the air will unite readily with the alcohol. Zinser Shellac has a fungicide in it's formula that prevents, or at least minimizes the degredation of the shellac due to bacterial sources, and this extends it's life significantly over other shellac products, but moisture getting into the alcohol can rust out the can. I have had problems with the shellac cans rusting and leaking, making a huge mess of my paint and finishes cabinet. I have since been using Bloxygen to drive the air out of the can in the hope that it will also reduce the amount of moisture that gets absorbed. Unfortunately, I've only been doing this for about a year, so I can't say that it is the solution yet, but keeping the shellac and the moisture in the air from uniting with each other certainly is. I'm hoping that the Bloxygen will not only keep the oxygen out, but will also keep as much moisture as possible out of my shellac. It does work great for keeping paint from skinning over in the can, so maybe it will help with the shellac problem.

DOT3 brake fluid contains mostly alcohol, and the old automotive brake systems were vented to atmosphere. Over time, atmospheric pressure changes would cause moisture laden atmosphere to enter the brake system. In a few years of this, the inside of the brake system would begin to rust because of the moisture that had entered and united with the alcohol. They now make sealed brake system reservoirs with a bladder that allows for the atmospheric pressure changes, but the bladder keeps the moisture laden air and the brake fluid separated, thus keeping rust from forming in the brake systems.

When you get water in your gas tank, you add Dry Gas, which unites with the water and also the gasoline, and then burns along with the gasoline and the water. So sometimes this alcohol/water thing is good, and sometimes it is not.

Charley

 

[Mike Stafford]

I quit buying ready made shellac. It always goes bad. I think the best way to store shellac long term is to not store it for long term use.

Instead I buy super blonde shellac flakes and a high quality denatured alcohol. I make mine in small quantities just when I need it. Generally I make a 1 1/2 or 2 pound cut which sounds like a lot of shellac. But I usually only make 4 ounces at a time one day ahead of when I am going to need it. I carefully measure half the alcohol (I use 190 proof denatured alcohol that I buy from Amazon) required for the cut I am intending with a measuring cup. I pour that into a clean jar and then carefully measure the flakes on an accurate scale. These I add to the half of the denatured alcohol in the jar and cap it tightly. I swirl the contents around and put it in the cabinet to dissolve overnight. The next day I measure and add the remaining denatured alcohol, the other half, and stir the two liquids together with a popsicle stick being careful to make sure there is no shellac flake sludge on the bottom of the jar. If there is you should decant the shellac through a fine filter.

I think you will like freshly made shellac over the store bought stuff. It flows better, dries quicker and seals the wood to perfection. Multiple coats can be applied very quickly and rubbed out easily with an abrasive pad between coats to achieve a really smooth finish. Sometimes it can dry too quickly before it flows enough to eliminate the brush marks. When that happens you will need to add some retarder to slow the drying process. I use retarder from Mohawk Finishes. You can add up to 10% of the volume to slow down your drying time which I had to frequently do in the hot dry/humid climate where I live. But you do have to remember that when you want to apply multiple coats as it does slow down the drying time.

Dewaxed super blonde shellac flakes appear to be very expensive until you realize how much shellac you can make and not have to throw away the shellac that goes bad. I keep them in the original plastic bag and store that bag in a new paint can which seals tightly. I like to make lighter cuts of shellac because of easily and quickly it can be applied. Of course there are other shades of shellac ranging from brown to red to orange to platinum blonde.

A gallon of good quality Denatured Alcohol (190 proof) can be bought from Amazon for about $40.

You can make a lot of shellac and I do mean a lot of shellac from one gallon of denatured alcohol and one pound of shellac flakes if you make small quantities as needed rather than buying it by the can and letting it good bad. It is actually cheaper than buying it by the can but you do have to plan ahead.

Below is a shellac cutting chart I downloaded from Shellac.net.

 

[glenn bradley]

There could be something in the 'rate of consumption' that applies to people's experiences. I have yet to have any canned shellac go bad and have been using it pretty regularly for 15 years or so. I did have a can leak as discussed but, I learned from that and no decant. Due to being between shops I have some that is well over a year old so I will be testing that prior to any use. It may be my first batch to "age out" due to sheer boredom; I should bill Zinsser for testing their shelf life for them.

 

[Ryan Mooney]

I use 190 proof denatured alcohol that I buy from Amazon

Mike, do you have a pointer to the brand you're using? I've had some mixed luck and the last few rounds managed to convince a friend to hook me up with some food grade "cleaning" alcohol (which is not denatured and a smidge over 97%, less if you let it sit out as without dryers it'll start absorbing moisture from the air). But that hasn't been an entirely reliable source and it's somewhat more $$ than decent DNA seems to be.

I'll second the mix on demand, although I have kept some extra in a jar for a few months with more headspace than seemed reasonable and it still worked fine.


I had two can's of Zinsser go.had (gelled out and popped the can seams), but the shop is HOT in the summer, and I actually may have gotten them from an estate sale so who knows how old they actually were.. so I'm not throwing any stones in that direction

 

[Mike Stafford]

Mike, do you have a pointer to the brand you're using? I've had some mixed luck and the last few rounds managed to convince a friend to hook me up with some food grade "cleaning" alcohol (which is not denatured and a smidge over 97%, less if you let it sit out as without dryers it'll start absorbing moisture from the air). But that hasn't been an entirely reliable source and it's somewhat more $$ than decent DNA seems to be.

I'll second the mix on demand, although I have kept some extra in a jar for a few months with more headspace than seemed reasonable and it still worked fine.


I had two can's of Zinsser go.had (gelled out and popped the can seams), but the shop is HOT in the summer, and I actually may have gotten them from an estate sale so who knows how old they actually were.. so I'm not throwing any stones in that direction

Ryan, I don't know much about alcohol and I don't drink but your 97% alcohol translates to 194 proof; that much I do know. So your alcohol is stronger than what I am using. I know that denatured alcohol is pure ethanol that has additives to make it smell and/or taste bad so people will not drink it.

Does the alcohol that is used to dissolve shellac flakes have to be denatured? I don't know that answer either. I am a creature who reads and follows directions. When I first started messing with making my own shellac I read that one is supposed to use the best denatured alcohol you can find and that is what I have done. My directions also said it was best to keep the mix in a jar with a metal lid in a dark place when not using it. I use small pickle jars (around here pickles mean Mt. Olive ) with metal lids both of which have been thoroughly washed in the dishwasher. I also keep my mix while the flakes are dissolving in a cabinet in the shop. And when I have completed the mix I place it back into the cabinet until I am ready to use it. How's that for being anal? Like I said I follow directions.

And yes, I have kept my mix for a week or two (in the dark) and there did not seem to be any problems with it. I don't know how long it takes before the mix begins to degrade.

I buy my denatured alcohol from Amazon. Here is what I use: https://www.amazon.com/Denatured-Alcohol-190-1-Gallon-128/dp/B07XSLD2XF/ref=sr_1_6?dchild=1&keywords=97%+denatured+alcohol&qid=1599041789&sr=8-6

It reads directly on the label that mixing with shellac is one of its primary uses. I can tell you this, this stuff dissolves the flakes readily and completely. I have only had a problem one time with mixing my own shellac and that was when I wasn't paying attention and bought shellac that wasn't dewaxed. I did use some denatured alcohol one time from Lowe's when I did not have enough of the good stuff and the flakes took much longer to dissolve than normal and the shellac did not flow as easily as with the good booze . Of course I am kidding about it being booze.

By the way Shellac.net is a good source of information on shellac. That is where the cut table I showed earlier came from and they offer good products for sale and links to suppliers. I have done business with them and they are a good company but they are in California and I am on the other side of the country and I can get the same or similar products from Amazon in much less time. With you being in Oregon the distance may not be a consideration.

 

[Ryan Mooney]

Does the alcohol that is used to dissolve shellac flakes have to be denatured?

It doesn't, in fact sometimes the denaturing agents can mess with the shellac (some of the DNA as I suspect the one you has problems with have a fair bit of methanol and less ethanol plus sometimes other stuff). DNA is however a whole lot cheaper than the non denatured stuff mostly because it can be sold under a different tax regime. So really pure straight ethanol is IMHO best but cost wise it's not very attractive. I paid close to as much for 750ml (about 0.2 gallons) as the Amazon stuff is per gallon. But I'd had a few annoying won't dissolve well and doesn't dry well experiences with the local home store stuff so wanted to take that out of the equation.

I hadn't found one I was very confident of trying online at a good price, so thanks for the pointer. I'm pretty much out of the high dollar stuff so it was good timing


I've bought a couple bags of shellac from shellac.net and also some from toolsforworkingwood.com IMHO they're both good stuff. At least I wasn't smart enough to tell the difference in quality.