Pour temp for polyester resin (castin craft)

[Dr_N]

I've found information here regarding 95 degrees being a good target temp to pour alumilite and maintaining color separation. Is there a similar "magic" temp to shoot for with polyester resin.

I just poured my first 4 attempts at resin casting this evening! We will see how it goes...

 

[Super Dave]

I'm not an expert on casting but living in Florida I have better luck in the hot summer months....

Dave

 

[TattooedTurner]

I live in AZ and prefer casting in the hot summer months as well. With PR it's a waiting game. You'll find that the effect you want will depend on how much the resin has started to gel. In the cold months it can take 20 minutes, in the hot months 3-5. Placing the container in a bucket of warm water helps speed it up during the cold months.

 

[chartle]

I go by how it flows off the stir stick as it thickens. But it can go quickly.

 

[its_virgil]

Reread the original post.the question is not the temp for just casting but at what temp is the catalyzed resin allowed to reach to allow color separation when colored parts are mixed together. Too soon and the colors dilute each other. Wait too long and no swirling happens. I wish I had the answer. Try contacting Brian Blohm.
Do a good turn daily!
Don

 

[Dr_N]

Reread the original post.the question is not the temp for just casting but at what temp is the catalyzed resin allowed to reach to allow color separation when colored parts are mixed together. Too soon and the colors dilute each other. Wait too long and no swirling happens. I wish I had the answer. Try contacting Brian Blohm.
Do a good turn daily!
Don

Thank you for clarifying for me, I often think in more detail than I speak or type! I was just wondering if there was a good way to determine how close the PR was to gel stage by temperature. I have begun to develop a "feel" for the thickening as I cast more. Only had one pour ruined by PR that was too think to pour from the cup...so far...

 

[TattooedTurner]

Thank you for clarifying for me, I often think in more detail than I speak or type! I was just wondering if there was a good way to determine how close the PR was to gel stage by temperature. I have begun to develop a "feel" for the thickening as I cast more. Only had one pour ruined by PR that was too think to pour from the cup...so far...

You pretty much nailed it. You'll get the feel for it by how thick it feels when stirring and also how it looks when you dribble it into the cup from the mixing stick. It looks like a coiled snake rather than mixing in right away, for lack of a better description. At this point you need to work fast, it turns to a thick gel in no time and you'll get air voids even with pressure.

 

[gotitjr]

As I was told. Pr does not really begin to heat up until after it has gelled and is too late to try to pour. As everyone else has mentioned you have to get a feeling for it. I have had many cups go from what I thought was still too thin to almost solid in just a few minutes


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[Dr_N]

Thank you for clarifying for me, I often think in more detail than I speak or type! I was just wondering if there was a good way to determine how close the PR was to gel stage by temperature. I have begun to develop a "feel" for the thickening as I cast more. Only had one pour ruined by PR that was too think to pour from the cup...so far...

You pretty much nailed it. You'll get the feel for it by how thick it feels when stirring and also how it looks when you dribble it into the cup from the mixing stick. It looks like a coiled snake rather than mixing in right away, for lack of a better description. At this point you need to work fast, it turns to a thick gel in no time and you'll get air voids even with pressure.

You're snake-like description seems pretty spot on, that and the thicker feel while stirring. Have/do you use a mold release with PR. My most recent pour seemed to really sick to the pvc when I tried to de-mold them today. Never really had a problem prior to today, though this is only my 5th pour, the others came out relatively easily.

 

[Brian G]

Were they new PVC molds? Sometimes the blanks stick a little with new PVC.

I lightly spray a paper towel with cooking spray and pull it through the PVC before I tape the end. That's my mold release for PR.

 

[Dr_N]

Were they new PVC molds? Sometimes the blanks stick a little with new PVC.

I lightly spray a paper towel with cooking spray and pull it through the PVC before I tape the end. That's my mold release for PR.

Thanks, I'll give the cooking spray a try. This was the third or fourth pour in that set of molds.

I've been using pvc pipe caps currently but I read that you tape your ends. Could you explain how you do that?

 

[chartle]

If pvc tubes just wait it may have not completely shrunk.

 

[TattooedTurner]

My experience is the exact opposite of Brian's. I have no problem with new pvc but after a few uses the blank sometimes sticks to the residual resin in the mold from previous uses. Pam cooking spray is a cheap release that works great. I don't use it on the pvc, but I've turned wood plugs for the tubes so I don't have to keep taping them up. A light spray & wipe with a paper towel keeps the resin from sticking to the plug.

 

[Brian G]

I've been using pvc pipe caps currently but I read that you tape your ends. Could you explain how you do that?

Sure. I use 1.5" painter's tape.

Cross one piece over the bottom:

Press and smooth:

Cross a second piece over the first and smooth:

Wrap a third piece around the first two:

Finished and ready for filling:

Whenever I think I can get away without wrapping the third piece around, I regret the decision and end up with a few leaks. There's also a risk of poking a hole in the tape if a piece of wire or something is used to swirl the resin in the mold.

If you're having success with end caps, there probably isn't any reason to stop doing that. Taping the ends takes time, but I'm never in a hurry when I'm casting. I cast for fun, not for profit.

 

[Dr_N]

Thanks for the pictures! I decided to try it yesterday and that's the way I went with the tape. No leaks! Good point on the stirring rod. I didn't use one yesterday, but good to have that in mind for next time.

 

[Dorno]

Reread the original post.the question is not the temp for just casting but at what temp is the catalyzed resin allowed to reach to allow color separation when colored parts are mixed together. Too soon and the colors dilute each other. Wait too long and no swirling happens. I wish I had the answer. Try contacting Brian Blohm.
Do a good turn daily!
Don

Thank you for clarifying for me, I often think in more detail than I speak or type! I was just wondering if there was a good way to determine how close the PR was to gel stage by temperature. I have begun to develop a "feel" for the thickening as I cast more. Only had one pour ruined by PR that was too think to pour from the cup...so far...

From what I have been told and also from my own work the simple answer in NO to a tempreture you just have to watch it and as you keep stiring it when it starts to feel and run like oil instead of like water give it a go then.

Cheers Ian

 

[chartle]

If you're having success with end caps, there probably isn't any reason to stop doing that. Taping the ends takes time, but I'm never in a hurry when I'm casting. I cast for fun, not for profit.

I use rubber stoppers covered in the tips from ripped up gloves. You just have to make your tubes a little longer since the stoppers go into the tubes a little bit.

 

[Dr_N]

My experience is the exact opposite of Brian's. I have no problem with new pvc but after a few uses the blank sometimes sticks to the residual resin in the mold from previous uses. Pam cooking spray is a cheap release that works great. I don't use it on the pvc, but I've turned wood plugs for the tubes so I don't have to keep taping them up. A light spray & wipe with a paper towel keeps the resin from sticking to the plug.

Man, the cooking spray worked wonders! My blanks slid beautifully out of their tubes today. Thanks for the advice.