[BondoKing]

You know I have had hardner go bad after 2 months, and I have also had hardner stay good for years.... I here soooo often how reactive reducer is only good for a couple months tops... I have used 18 month old reactive reducer before without complications, same goes for the hardners/activators... Am I missing something along the lines here?? I have not had any failures with the jobs I have done with these, nor is there any sanding problems, buffing problems etc..... What is the catch???

Jim and I have talked about this before among ourselves, so now I will bring it in here..

BK

[crashtech]

Maybe the quality of the seal on the lid has a lot to do with whether a product will last or not. The volume of oxygen in a partially used container is probably not enough to ruin the rest of the hardener, but if the container can "breathe" by expanding and contracting, it will be introducing new air into the container every day. My trick is to invert the container briefly after closing the lid, hoping that the product itself will help fill any small gaps in the seal.

[powderbill]

I agree with crashtech's comment that the seal of the container of isocyanate curing agents is critical. Despite some previous comments, there is actually little or no danger of isocyanate reacting with oxygen, but considerable problem with atmospheric moisture. (There are also some possible slow side reactions that involve self-condensation, which can probably be minimized by storing in a cool place.) If stored in a cool place and not repeatedly re-opened, I've had quart metal cans of isocyanates stay in good shape for over five years. Conversely, I'm sure we've all seen cans go solid pretty rapidly if stored in hot conditions and re-opened repeatedly under conditions of high humidity.

To BondoKing's question, in general I think that the majority of "bad" things that can happen to isocyanate during storage would manifest themselves by a noticeable viscosity increase, up to the point of gellation. So, as long as the viscosity appears to be reasonably close to that of fresh material, I would not be overly concerned about the film properties obtained from use of somewhat aged isocyanate. (Probably less danger there than would result from using a non-urethane reducing solvent that has some alcohols in it!)

I'm still concerned, but not positive one way or the other, about the advisability of using glass for eliminating air. I've sent a message to BarryK asking for his opinion. If he's not certain, I may ask a guy I know from Bayer (one of the manufacturers of isocyanates) his opinion on this one.

[BarryK]

WOW!,
Had not herd this in years and have NO experience as far as testing to prove either way.

But like PowderBill, I was always told the silanol was a problem and not to do it. On top of that just plain contamination from the marbles would make me wonder.

Like PB said use use your mig gas or just get the top on as soon as your done pouring and make sure sealed good.

[n66ht]

Using marbles will just take up space pushing the level up closer to the top leaving less air in your container thus allowing the product to last longer. I use argon gas from my tig welding bottle and have never had any problems. The gas being heavier than the air pushes' it up leaving a layer of gas to separate the hardener from the air which contains moisture that cures iso's. Bloxygen does the same thing as the welding gas. But you need a good seal for all this to work.

[Dailey]

Well, have we all got beer fridges in the garages. Keep your hardeners in the fridge, seal it with some glad wrap or plastic lunch wrap and push it further into the can eliminating as much air as possible. Bang the lid on and you should be ok. Hey its worked for me, and if its that long since you last painted a car or your ride, and you want to be sure, turf the can and start afresh. Dave