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View Full Version : Shelf life of lacquer and/or sealer



deepsplinter
12-06-2008, 09:23 AM
I sprayed some drawers with pre-cat lacquer sealer yesterday at about 5:00 PM. They were still tacky at 9:00. They're good-n-dry this morning. I've been using out of this (5 gal) can for well over a year with no problems.

I know lacquer has a shelf life, but no idea how long. The only thing I find on the can that mentions a date is, "Inst. Rev.:05/31/06"

Is this stuff starting to go bad, and if so, is that why it took so long to dry?

TDHofstetter
12-06-2008, 09:40 AM
Shellac has a mixed shelf life of about two years at the outside... but it's hard to imagine why lacquer would; they act in two entirely different ways, the lacquer being simply dissolved in a solvent (lacquer thinner). What was the temperature, and was there plenty of ventilation for the solvent to flash off? What was the humidity?

-- Tim --


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Tony B
12-06-2008, 10:03 AM
Pre-Cat lacquer is only good for i think 5 months from the day it is mixed. You will have to call the menufacturer or the local paint store with that brand to find out.
When I bought Sherwin Williams pre-catalized lacquer, they marked to expiration date on the can. Pre-Catalized means that the paint store mixed the 2 components for the entire 5 gallons when you purchased it. They "pre-Catalyzed" it for you. My best guess is that the stuff you have left over is way past its expiration date. I personally would not use.
Pre- Catalyzed lacquer should be tack free in just about 5 minutes. You should be able to move things like table tops without thumb printing them in 10 minutes.
Once you go past the shelf life, which you did, even though it may seem hard to you, it is no longer the product that you think it is. Call the manufacturer and ask for technical support and they will tell you exactly what to expect.
As a side note, Catalyzed lacquer is where you get the 2 components and you mix them yourself as you use them. They have a shelf life that is good for several years. I bought the Pre-Cat only because they didnt have the catalyzed stuff in stock at the time.
Tony B

Tony B
12-06-2008, 10:23 AM
When I buy a 5 gal can of lacquer, I also buy empty 1 gal cans for about a buck apiece and fill the 1 gal cans. I pay about $135 for the Pre-Cat Lacquer and 5 more dollars for clean empty cans is a wise investment.
Tony B

cabinetman
12-06-2008, 04:34 PM
You mentioned that you sprayed a lacquer sealer. Some packaged lacquers that are nitrocellulose are sold "ready to spray", and may not need a catalyzer, but may require thinning with lacquer thinner. This applies to acetone based lacquers (thinned with lacquer thinner), which are different than "acrylic lacquer" which is also thinned with lacquer thinner, but an acrylic lacquer thinner.

Acrylic lacquer thinner can be used in either NC lacquer or acrylic lacquer, but lacquer thinner designated for NC lacquer should not be used with acrylic lacquer.

If your product is what's called "waterbased lacquer", that is a whole different animal than solvent based lacquer and it thins with water, not lacquer thinner.

Unless you dumped retarder into your batch, it shouldn't take that long to flash dry. Try thinning some with lacquer thinner (up to 50%) and see what happens. The label on your can may have suggestions for thinning.

deepsplinter
12-06-2008, 04:58 PM
Uggh!

That wasn't the answer that I was looking for, but I'm betting you're right. It's expired.

Always before, this stuff has worked like a charm.

I'll call the manufacturer Monday.

Thanks

Jim_J Lazy 3
12-06-2008, 11:40 PM
"pre-cat lacquer sealer" huh,... I use a vinyl sealer myself, still thins with lacquer thinner though. Maybe I'm not understanding... are you spraying a seal coat with the lacquer, and then building the finish from there? If so, is this how you always do it? I only ask because I've never had much success doing it that way. Was the temp on the cold side, and/or the humidity on the high side? If so, then do like Mike says and thin things 50/50 and see what happens.
One other question, how big are the drawers? deep? bottoms attached? (ok, that's 3 questions). The inside of deep, high sided drawers, with bottoms attached can take forever to dry if it's cold and damp, and you've sprayed a heavy "real wet" coat.
If the lacquer mixes with thinner, you know, no "floaties", it's good to use. I personally haven't experienced any shelf life problems. I'll occasionally find a can with a "dribble" left in it for one reason or another, and I know it's old... but if it mixes - it'll spray.
Oh, and I use "Gemini" brand. In my neck of the woods, it's sold at KWAL paint stores............Jim@JLazy3

"The only thing certain in life ...is uncertainty!"

deepsplinter
12-07-2008, 02:22 AM
>"pre-cat lacquer sealer" huh,... I use a vinyl sealer
>myself, still thins with lacquer thinner though. Maybe I'm
>not understanding... are you spraying a seal coat with the
>lacquer, and then building the finish from there? If so, is
>this how you always do it?

Yep, one seal coat of pre-cat lacquer sealer, then two or three coats of pre-cat lacquer. That's the way I was taught way back when.


>Was the temp on the cold side, and/or the humidity on the high side?


Nope, temp was about 65 and humidity about 35. (forced air heat)


>One other question, how big are the drawers? deep? bottoms
>attached? (ok, that's 3 questions). The inside of deep, high
>sided drawers, with bottoms attached can take forever to dry
>if it's cold and damp, and you've sprayed a heavy "real wet"
>coat.

Drawers are 22"x20"x6", and I did go pretty heavy on the bottoms.


>If the lacquer mixes with thinner, you know, no "floaties",
>it's good to use.


It mixed just fine, like it always has before.

FWIW, it's made by Mohawk.

I'm not gonna do any more to the drawers until I talk to somebody from Mohawk.

Postman
12-07-2008, 07:34 PM
I think you told me one time that you got the Gemini pre-cat lacquer from Sherwin Williams. I noticed on the can that it says not to spray more than 2 coats because it may fail. ???

deepsplinter
12-08-2008, 08:36 AM
I just talked to a guy from "Mohawk Finishing Products". He said that I can safely use their pre-cat lacquer sealer three years from the manufacture date.

He couldn't explain why it took so long to dry the other day (too many variables)

Good news. I'm gonna carry on.

Nope, not me Joe. I've been using "Trinity" or "Mohawk".

Postman
12-08-2008, 09:55 AM
Trinity! Yeah, I remember. Maybe I'll switch over to that.

Tony B
12-08-2008, 09:56 AM
Deep
I'm sure you asked the right questions but I will ask you again.
Did you give the Mohawk guy the 'mixed' date and did he give you the 'shelf life' of 3 years or the product life after it was mixed of 3 years?

Tony B

deepsplinter
12-08-2008, 01:55 PM
This morning's conversation went something like this;

me...What is the shelf life of your pre-cat lacquer sealer?
him (with no hesitation)...Three years.
me...I tell him the story about it being over two years old and taking too long to dry, but feels OK the next morning.
him...There's lots of variables involved (heat, humidity, how heavy was the coat, how much was it thinned, etc...) If it feels and looks good, I'm sure it'll be fine.
me...Alright, good news.

So, I go out to the shop and spray a coat of pre-cat lacquer (purchased the same time as the sealer) on the drawers. It goes on and dries just fine. Then I come in for lunch and read your post #11. That got me thinking/rethinking. So I get on Mohawk's web site and find their reference chart that says the "pot life" of their lacquer and sealer is 6-12 months. UGGH!!

So I call Mohawk back, the same guy answers. It goes something like this;

me...You told me this morning that your sealer is good for three years, but your reference chart says 6-12 months.
him...What it the product number. I need to look it up.
him...My chart says 6 months. I think you need to talk to Bob.

Now I'm talking to Bob.

I tell him the whole story.

him...I don't like to put a number on "shelf life", too many variables. If your sealer did eventually dry and your top coat of lacquer dried good, then I'm sure you will be fine.

Well, I sure hope Bob is right.


Wish me luck.

Tony B
12-08-2008, 07:01 PM
I wish you luck. The main thing is that the primer dried and dried to a hard finish.
I would think that the guys at Mohawk would realize that the 2 parts were mixed before or at the time you bought it. Then they would be talking pot life and not shelf life. Shelf life is the life of a product starting from the day its made. Pot life of pre-cat starts from the day its mixed and once mixed, it's life is much shorter.
In either case, you should be OK if everything gets hard like it's supposed to.
Unless I'm using a paste wood grain filler or going to use glazing, I dont use a primer. I just thin out the pre-cat.
Tony B