Use-by dates for lacquers

[Arron]

I am wondering about how strictly one needs to follow the 'use by' dates on lacquers.

In my case it's Wattyl Stylwood and Wattyl Readiseal, but I expect the question would apply to any industrial nitrocellulose lacquer and its modern derivatives.

The problem is I have overbought on 20 litre drums - I thought I could use them within the year but now see that I can't. The product literature gives them a 12 month use by date. I dont want to be throwing them out but I don't want to be using them if I'm not confident in them.

So does anyone have any experience in this area ?

Soundman, if you are out there, I'm sure you would know.

Cheers
Arron

[dinosour]

In my humble opinion the use by dates are to cover the manufacturer/maker but I would ring technical people at Wattyl, they usually give good and reasonably unbiased advise.

[Mobyturns]

I've been using Wattyl Stylwood 30% for quite a while but I am not a big user volume wise. I purchase 4lt and my product is way past the 12 months use by date and still looks and sprays fine. I always decant the 4lt down into three 1lt cans and two 500ml cans that I purchase from a paint supply firm. As I use the 500ml cans I then decant from the 1lt cans down into fresh 500ml cans. Keeping the volume of air inside an opened can to a minimum seems to help greatly.

The Rediseal sanding sealer seems to go to a deep honey brown quite quickly in the smaller cans once opened.

[soundman]

The first thing to understand about laquers is that they work mostly by solvent evaporation.
Reactive finishes that work by reaction do not keep particularly well ... the resins react with oxygen in the air and the driers degrade and react.
My understanding is that this is far far less of a problem with simple true laquers ..... particularly if they are kept in sealed containers.

Worst comes to worse .... draw off a sample at the time and see how it sets up. ....... remember if you do something with simple laquer and it turns out to be a disaster ..... you can scrub it all off with a rag and some solvent.

cheer

[rob streeper]

Heat is the primary problem with most finishes. Lacquers are more stable chemically than most other classes of modern wood finishes. Keep them cool and they should hold fine. I have a couple of cans that I stored unintentionally for about four years - no problems.

[Arron]

Thanks for the input guys.
I will check their seals and move them to the cool space under the house.
Cheers
Arron