Slow setting PR

[mhbeauford]

Does the catalyst for PR get old? I cast some today and use 5 drops per oz. The sample in a cup is just jelling good after about 7 hrs. Haven't opened the pressure pot, will leave it over night. Usually it jells in about 40-60 min. Had the PR and catalyst about yr.+ This is the first time I have used it in about 3-4 months. I noticed last time was pretty slow, had to heat the blocks to get them good and hard. First use seemed to set much faster when fresh. PR from Douglas & Sturgis.

 

[Tim'sTurnings]

Are they clear blanks or did you add colorant? Different kinds of colorants can drastically change the set up time. DAMHIKT.

 

[Lenny]

I think the shelf life is generally 1 year from the time you open it. Other factors like how it was stored can also have an effect. That would be my GUESS!

 

[EBorraga]

USComposites now has on their label - Use within 6 months.

7 hours to setup in Texas seems whacked!! It could of been the hardener, but like Lenny said, it could be your coloring agent - if it wasn't a clear cast.

 

[Ruby pen turning]

I have cast blanks that are just fine. The next time I cast they dont seem to harden. So I switch to a new bottle of MEKP (hardener) and all was well again. I do think also colors sometimes play a part.

 

[mhbeauford]

I used colorant from Hobby Lobby said for PR and some pearlx. I suspect the catalyst.

 

[PTownSubbie]

I used colorant from Hobby Lobby said for PR and some pearlx. I suspect the catalyst.

Do a 1oz test cast. Put 1oz of resin in a cup and add 3-4 drops of MEKP. If it doesn't harden, it is the MEKP. If it hardens, it was too much colorant....

 

[Dai Sensei]

I have use catalyst that is over 3 years old without issues. How warm was your mix? Remember setting takes longer under pressure as the boiling point/setting point is higher under pressure.

 

[bruce119]

MEKP and the PR dose go weak or bad BUT also remember mass greatly effects cure/heat. For instance take 1 oz. w/3 drops MEKP put in a wide cup maybe only about 1/8" deep it will take hours to cure. Take the same 1 oz. put it in some tall and thin like a 3/4" tube now it will be about 2" high will cure much faster more mass generates more heat.

Something to think about. You need to adjust the MEKP according to mass. That's only one of the many, many variables.

.

 

[Jim Burr]

I'm thinking 7 drops per oz was the norm, but as mentioned above...temp is a huge factor in PR setting up.

 

[BRobbins629]

Go to the goodwill store and buy a $5 toaster oven. Set to about 150F. I suspect as others did that its the colorant, but a few hours at this temperature and it will cure.