vinylester shelf life and the definition of "promoted resin"

[loop]

first off thanks to all who offered advice on my core thickness thread. It will be 1/2" balsa with vinylester.
What is the shelf life of vinylester resin? So far I've read 2-3 months
The reason I ask is I have found about 40+ gallons of Hetron 922L25 for practically free. It was deliverd to the customer in September and only a small amount was used. Is this stuff already too old?

I only need 5-10 gallons for my Allison and a couple of other projects that I expect to have completed in the next 1-2 months. I dont need a 1/2drum of resin left over. Unfortunately they wont sell me just what I need. They are moving and want everything gone. I would give away the rest to anyone who wanted it if its not already outdated. Surely wouldnt want to have to pay to get rid of it.

Could someone please explain what "promoted resin" means. And please, dont use too many big words. Explain it like your talking to a dumb Texas redneck with a short attention sp......

[bigboy]

If I were you I would go and check it out. Just mix a batch and check out if it cures like it should.

[ondarvr]

It should be OK.

I'm not familiar with that code, did they say it was pre-promoted, or un-promoted? I ask that because the last two digits are 25, which could easily be the gel time, if that is the gel time, then its promoted. Un-promoted resin hasn't had the correct chemicals added for it to start crosslinking and cure, so it has a much longer shelf life. Old resin tends to drift out in gel time and drop in viscosity.

VEs tend to drift in gel time faster than polyesters, so they frequently come un-promoted.

[loop]

Thanks for the replies
They are going to send me a picture of the label. I will post that when I get it.
Unfortunately they know little about it. Their father purchased the resin and alot of other chemicals. He did repairs and made some small parts. He passed away shortly after buying the stuff. The family members were just cleaning out his building and nobody wanted to deal with all the chemicals and such so they just want it gone.
What do you mean by gel time "drifting out"?
Would a drop in viscosity mean its thickening or thinning?
If it is un-promoted what chemicals are added to promote it and can this be done in small batches,say 1-5gallons at a time?
If this resin were to start going bad shortly after I got it, could it be catalized in small batches so it could be easily disposed of?

[Riverman]

From what I remember the promoting chemicals are too nasty to leave the warehouse - resin is promoted prior to delivery to the customer.

[ondarvr]

Shelf life is determined by how long the resin will still meet certain specs met during the QC process. Drift is just a change in gel time or viscosity from where it started. <O</O
<O</O
Lower viscosity means the resin will appear to be thinner.

A resin can have a gel time from around 5 minutes to about an hour and there is a range met for QC purposes. If the resin has a gel time of 20 minutes it means the range would be from around 18 to 22 minutes or maybe 17 to 23 for this product, anything in this window would be OK. The manufacturer is saying that for at least 3 months (the shelf life) it will still be in this range, after that it may or may not still be in this range. It doesn't mean the resin is bad or can't be used, just that some production processes rely on a specific gel time and if it drifts out a few minutes it may cause problems in the plant or in the quality of the product being made. For doing small repairs or making parts in a non production environment it won't make a big difference.

Viscosity is set in the same way.

Cobalt and DMA are used to promote resin, mixing either of them with catalyst can create a small bomb, so you want to keep them apart. The amount of each one determines the gel time and gel to peak of the cure profile. Gel time is the length of time between adding the catalyst and when it becomes very thick, about like pudding. Gel to peak is from that point to where it reaches its highest temperature.<O</O
<O</O
Cobalt is dark purple and DMA is a light amber or yellow, both are liquids.<O</O
<O</O
Cobalt has more of an affect on the gel time and DMA has more of an affect on the gel to peak, so by adjusting the amount of each you can fine tune the resin for exactly how you want to use it.<O</O
<O</O
When you get a pic of the label just Google it and look for the data sheet, this will tell you if its promoted or not.


VE resin tends to drift in both gel time and viscosity faster than polyester, this is why it normally comes unpromoted

[loop]

Wow!
Thanks for alot of very useful info.
So if its unpromoted can i buy the cobalt or DMA?
Is it typical for a small shop that does mostly repairs to buy the resin unpromoted and add the chemicals as needed?
sounds like the biggest problem with a resin thats on the older end of its range would be a less predictable gel time. Correct? if so that shouldnt be too much of an issue for my project

[native2]

I have used cobalt to promote some VE Durakane resin. You only need a small amount of cobalt. Be careful not to add too much as it will practically go off while you are stirring it.

[ondarvr]

Wow!
Thanks for alot of very useful info.
So if its unpromoted can i buy the cobalt or DMA?
Is it typical for a small shop that does mostly repairs to buy the resin unpromoted and add the chemicals as needed?
sounds like the biggest problem with a resin thats on the older end of its range would be a less predictable gel time. Correct? if so that shouldnt be too much of an issue for my project

Yes, you can buy both of them, you may only need one though, it just depends on the resin.

Yes, most VE is sold un-promoted, the data sheet will give you options for gel times, you just vary the amount of cobalt.

Correct, if it is already promoted, and if the gel time is the last two digits of the product code (common), then it may be 30 minutes or so after several months, you could still add a small amount of cobalt and bring it back into spec if needed.

[ondarvr]

http://www.ashland.com/Ashland/Stati...0922%20TDS.pdf

[johnboy 88 vegas]

The only thing I have found out about shelf life is that if its kept in a climate controlled environment it tends to last a lot longer than if kept outside where temperature change frequently occurs. If it sits in the direct sun it wont last too long. Old resin=more hardener.

[Liqui-Fly]

Do the experiment. Resin is most likely fine. The resin is most likely simply catalyzed with MEKP. The MEKP catalyst is more likely to go bad than the resin. Mix a small batch with the suggested catalyst amount and spread some out. Promoter is sometimes loosely used and means the same thing as catalyst. There are all types....room temperature cure, moderate temp. cure and high temp cure. Resins systems won't have a room temp. cure promoter in them for obvious reasons. I think many manufactures are very very careful about the shelf life they will assign to materials given they have limited control of how it will be stored after it leaves the plant. I have some really old stuff that still cures just fine.

[loop]

good news
thanks again to all that have replied. I've really learned alot.
The resin seems to be fine. I mixed up a small batch and it set up just fine at 2%hardener. It was about 50 degrees outside.
found it on craigslist. This is what I got for $250,plus about $80 in fuel to pick it up,plus a breakfast biscuit and a What-A-Burger w/fries

35 gallons of Hetron 922L25
30 gallons of acetone
2-5 gallon pails of White gelcoat,one unopened
almost 2 gallons of MEKP, one unopened
2- 5gallon pails of Valspar EZ bond putty,one unopened (see below)
1 gallon mold cleaner
1 gallon mold sealer
1 gallon mold release
And best of all the seller gave me the the phone# of a guy who may want to buy anything I dont use.

regarding the Valspar EZ bond. I cant find anything info online except the MSDS. If anyone knows anything about it please let me know. I did mix some up with MEKP @2% and it hardened,very slowly in 50 degree temps
Thanks again

[OFFSHORE GINGER]

Hey guy that is just awsome , and did you use a gun . Ha Ha Ha Ha just kidding .

[Liqui-Fly]

I have never heard of a laminating resin being promoted at 2%. Only some gel coats. Make sure you get it right....it's typically 1%. Too much cataylst can give you a resin with different properties.