Old Polyester Resin

I have never kept resin that long in the past so I have no idea what to expect from this old batch that I have now got. It has crystallized around the top and formed some lumps so I strained it and I have used it to make some bog for a non critical non marine application.

How compromised is this stuff? I don't think I would use it for a critical application but I would like to know what to expect from it.

+ I stuck it in jars for the lack of a suitable container, I suspect that it should be stored in something that keeps the light and air out. I that right? I have always had it in tins before.

Cheers
M

 

Get rid of it.

 

Using old resin isn't all that unusual for me...customer has a project and provides the material...it can be a crap shoot some times. I've found old resin to have some of the following characteristics:

The instability of the product can make it difficult for me to accurately time the gel stage of the resin. It can Flash off too soon or require extra heat and time before it kicks at all. Resin run out can also be a serious issue where it just doesn't want to kick at all...this can lead to big problems.

Depending on the situation and it's degree of suitability I'll either stop using it altogether or blend it (in small doses) with some fresh resin. It's up to you of course, but Ike is right...probably better to just get rid of it.

MM

 

Yeah I figured it was not up to much and it is a little slow going off but it still makes up a good filler for odd jobs. Like I said what I am doing is not critical.

"Just chuck it" didn't really answer what I wanted to know!

So if I get it to go off then is it still as good as new product? I'd assume not... but?!

 

Well using it for filler is probably exactly what I'd do with it. I think you've answered your own question...is there something I'm missing?

MM

 

No, I just didn't know if it was going to do something silly like crumble after a month!

 

The gelled stuff you saw around the top doesn’t necessarily mean the resin has a problem (it’s not good though), some resins tend to do this rather quickly. As the chunks form they will speed the process by causing more cross linking to take place.

As the resin ages the promoters tend to become less effective and the gel time will drift longer, some resins types are more stable than others, and within types some formulas are more stable than others. Then it comes down to each batch and how the product was stored. The more the gel time drifts out the poorer the cure, small amounts of drift are normal and expected during its shelf life, but as time goes on the physical properties will be reduced, sometimes dramatically. There is no way to say exactly when the resin will be of no value due to the many variables, so the shelf life is set so most resins will still be very good on that last day. After that it’s up to you as to whether it can be used for a particular purpose.

The viscosity will also prop, so if used in a laminate there is a better chance it may drain out of the glass easier. As it continues to age some cross linking will take place and the viscosity may increase and gelled particles can form.

 

Thanks.

Re: Storage.

I assume cool and dark is the best way to store this stuff, would that be correct?

 

You are correct, cool and dark, along with well sealed.

 

Resin Shelt Life, etc.

Moggy,
Here's information on Shelf Life, Pot Life Etc, I found for a Urea Resin, Ultra Cat PPA Venear Glue. Don't know your product brand but this should be somewhat relevant.

"Pot Life
Once mixed with water, the resin begins curing/hardening. The amount of time between when it is first mixed until it reaches the unusable point is termed pot life. As with most directions for gluing, this is a dynamic value. It will change, primarily due to temperature. Hotter temperatures yield a shorter pot life, and vice versa with colder temperatures. There is no problem putting mixed resin in the refrigerator to extend its pot life; however, it should not reach below 55°F, as it will thicken to the point where it will not spread well. Do not freeze the adhesive. If you opt to refrigerate the mixed glue, be sure to bring it back up to 70° before using it.

At 70°F pot life is less than 4 hours.
The adhesive will continue to cure until it is rock hard—generally within 24 hours.
Only experience and a careful eye will tell you the point when the mix is unusable, so err on the side of performance rather than yield. When it has thickened to the point that it is not spreading well, consider the mix unusable.
Before it gets too heavy, a small amount of water (up to 3%) may be added to keep the glue thin enough to be used. Additionally, a new glue mix can be added to a small amount of thicker product, and after being stirred, will yield a new full pot life.

Storage
Because Ultra-CAT is extremely hygroscopic, it should be stored in a tightly closed container in cool, dry place at all times. You can expect 12 months of shelf life when Ultra-CAT is stored properly.

Keep in mind that the rated shelf life pertains to unopened containers stored in a cool (60°-70°F) and dry place. Higher temperatures will severely reduce the shelf life (only 6 months @ 90°F), and exposure to high humidity may cause severe lumping or actual catalyzation of the powder resin.

Times and Conditions
Open time: 20 to 30 minutes
Assembly time: 40 minutes
Pressing time: cold vacuum press - 4 to 6 hours @ 70°F
Pressing time: heated vacuum press - 2 to 4 hours @ 90°F
Dry shelf life: 12 months

Hope this helps

pw
"

 

Thanks!