How long to maintain PP pressure ?

[Gordon]

I've been doing some searching for the length of time it is necessary to maintain the pressure pot pressure - and it appears to be about 20 hours.

Why so long ? - wouldn't it be no longer than it takes the resin to gel (10-20 minutes) ?

Thanks

 

[Draken]

The resin is still pliable when gelled, as it hasn't hardened yet. If you release pressure too soon, any air bubbles can still expand, voiding the use of the pressure pot in the first place. Best to keep the pressure on until it has hardened. Since it is hard to tell when it has hardened in the PP, and it varies with temp, humidity, and amount of catalyst, most choose a safe route and leave it on for at least several hours. I tend to cast in the evening, let the pressure sit until the next evening, when I have time to get them out of the pot.

YMMV.

 

[Gordon]

James - - thank you -wish me luck.

Gordon

 

[gketell]

Gordon, I do like James except I usually cast Saturday evening and open Sunday morning. Of course, if time is money alumilite can be removed in 1 hour.

GK

 

[Gordon]

Thank you both - - - I'm presently using Castin Craft PR - what psi pressure do you use ?

 

[Blind_Squirrel]

Originally posted by Gordon

Thank you both - - - I'm presently using Castin Craft PR - what psi pressure do you use ?

Depends on what I am casting. For straight resin blanks (no tubes) I go with 4 bar (approx. 60 psi). If I am casting labels I drop it down to 15-20 psi.

This may beg the question "why use a higher psi if you get crystal clear casts using 20 psi?" My answer is because I can.

 

[Draken]

I've had good luck at 20 psi, and not so much so at 60 psi. [?]

 

[Neodon1]

I use alumilite for many reasons, but to answer your question,
I found this brief article on their website.

http://alumilite.net/HowTos/PressureCastingClear.cfm

"We let the material set for 45 minutes before releasing the air pressure and removing it from the Pressure Pot."

I followed these instructions and all was well, no bubbles.
clear and set (cured).

Hope this all helps,
Neodon1 [8D]

 

[Gordon]

Neodon -

Thanks for the internet link.

 

[Neodon1]

Your welcome.

Neodon1 [8D]