18 replies to this topic

[Aaronw]

I've finally got a work space set up in the garage for casting again. In the past I had a room in the house so temp control was not an issue, the garage is not heated so this time of year it probably averages 45-50 degrees. Other than possibly making the silicone and resin take a little longer to cure has anyone found cold weather to create problems?

[jeffb]

most resins are very temp and mositure sensitive. i used to cast in my garage and had a lot of trouble with humidity in a cool enviroment. try to keep it as dry as possible.

[BigPoppa]

I store the molds and resin in the house and the pressure pot in the garage. When it's cold out, I put the pot on a hot plate set just warm enough to touch, I guess you could use a thermometer to be more exact. I turn it on while I'm setting up so it's ready by the time I put the molds inside. I'm not in much of a hurry so I usually leave it on overnight, flip it off in the morning and pull pieces in the evening. The cool down seems to help pop them out.

[CAL]

It's not recommended.

Humidity and moisture is more of a problem than temp, so you defiantly want to keep it dry and the humidity low.

What I have found even at 60-65 degrees, which sometimes it gets that cold where I cast a couple of problems.

1. Drastic reduction in cure times.
2. The color and grain of the cured resin is slightly different. Lighter and grainer when it’s colder.
3. Parts stay soft for several days even after it warms up. compared to when it's 70 I can make a rock hard cast in 30 min
4. And I have had zero luck pouring RTV molds when it’s that cold. The center of the mold never seems to cure. So I just to pour RTV unless it's 68 or warmer.

I can't imagine casting resin at 40-45.

Edited by CAL, 27 November 2007 - 07:56 AM.

[Aaronw]

Well then I guess I'll need to get a portable heater. I kind of thought it might be a problem but wasn't sure.

[CAL]

Well then I guess I'll need to get a portable heater. I kind of thought it might be a problem but wasn't sure.

I am not sure where you live or your what your humidity is like.

you probably what to get an Hygrometer to keep track of relative humidity and dehumidifier if necessary.

I live in the high-plains desert average humidity 10-20% so it's not a problem but for a couple times a year when we get 3 feet of snow.

[Modelmartin]

Resin and rubber set-up and cure from the heat produced by chemical reaction. The cold temps kill the heat and then kill the curing resulting from the heat. I once filled a mold with resin and left it in temps like you described and came back the next day and the resin had set-up enough to get it out of the mold but was still very soft. I could take the casting ( it was a bodyshell) and crush it into a ball with my hand and lay the ball on the table. 10 minutes later it unfolded itself and resumed it's original shape! You could do it over and over! I don't know if I could ever duplicate that result again!

Moisture is more of a problem for resin shelf life than for a one-time casting situation. In Urethanes it will turn the A part into gravy eventually.

[CAL]

Resin and rubber set-up and cure from the heat produced by chemical reaction. The cold temps kill the heat and then kill the curing resulting from the heat. I once filled a mold with resin and left it in temps like you described and came back the next day and the resin had set-up enough to get it out of the mold but was still very soft. I could take the casting ( it was a bodyshell) and crush it into a ball with my hand and lay the ball on the table. 10 minutes later it unfolded itself and resumed it's original shape! You could do it over and over! I don't know if I could ever duplicate that result again!

Moisture is more of a problem for resin shelf life than for a one-time casting situation. In Urethanes it will turn the A part into gravy eventually.

ooooohhhh is THAT what that is in my A bottle. I been trying to figure it out for a week now. All the sudden one day it was starting to crystalize.

I had some goofy reaction but was still able to cast decent parts.

My Pur A Kast never did that and I recently switched to Smooth On 320 so I never experienced that before.

Edited by CAL, 27 November 2007 - 03:39 PM.

[Modelmartin]

ooooohhhh is THAT what that is in my A bottle. I been trying to figure it out for a week now. All the sudden one day it was starting to crystalize.

I had some goofy reaction but was still able to cast decent parts.

My Pur A Kast never did that and I recently switched to Smooth On 320 so I never experienced that before.

My resin guy has told me that theoretically you can warm up the A and get the moisture out but have never tried it. I am sceptical to say the least and don't like chemical fires and fumes, etc.

[CAL]

My resin guy has told me that theoretically you can warm up the A and get the moisture out but have never tried it. I am sceptical to say the least and don't like chemical fires and fumes, etc.

Yeah, I am not sure I'd want to try that either.

Only a little went bad. I keep the master container well sealed and use little 2 or 4 oz squeeze bottles for easier use.

[resinslinger]

I'd cast inside where it is warm and dry but that is just me. CB

[Aaronw]

I'm in Yosemite National Park so humidity is pretty moderate, its just the cold this time of year.

I think I've got something set up that will work now. I'm storing my silicone in the house, so it doesn't get really cold, then I'll take it out when I'm ready to make a mold. If I pour silicone during the day its warm enough, then I'll bring it inside after its set up a bit and less likely to create a disaster. Seems to be working ok. The actual casting of resin can be done with a portable heater out in the garage where no one except the mice will complain about the smell.


Thanks for the help.

[CAL]

I'm in Yosemite National Park so humidity is pretty moderate, its just the cold this time of year.

I think I've got something set up that will work now. I'm storing my silicone in the house, so it doesn't get really cold, then I'll take it out when I'm ready to make a mold. If I pour silicone during the day its warm enough, then I'll bring it inside after its set up a bit and less likely to create a disaster. Seems to be working ok. The actual casting of resin can be done with a portable heater out in the garage where no one except the mice will complain about the smell.
Thanks for the help.

That will probably work. I could still cast resin when it was colder than suggested. It was the silicone molds that never cured when it got too cold.

What are you using for cast resin?

[resinslinger]

That will probably work. I could still cast resin when it was colder than suggested. It was the silicone molds that never cured when it got too cold.

What are you using for cast resin?

Not really worried about the resin....more worried about my bones and joints....I'm one of those old geezers and the cold gets to me.....

[CAL]

Not really worried about the resin....more worried about my bones and joints....I'm one of those old geezers and the cold gets to me.....

I hear ya. That's why I stay inside

I was just wondering what resin Aaronw was using becuase I don't get much smell off 320 at all, but I have smelled some stinky resins.

[Aaronw]

I hear ya. That's why I stay inside

I was just wondering what resin Aaronw was using becuase I don't get much smell off 320 at all, but I have smelled some stinky resins.

I use Quik cast, the smell is not really that bad and the new formula they went to smells even less but I prefer not cast in the house. The clear on the other hand reaks.

Mostly its the mess of the occasional spill, but I'd prefer not to have everybody breathing the fumes either. There really isn't a good place to work in the house anyway. I have a model bench in the house but casting usually isn't as time consuming so I don't mind throwing on a coat, in the past I did my casting on an outside work bench so having a roof over my head is quite an improvement.

[Aaronw]

Just an update on cold weather casting. It is working fine to cast out in the garage, I keep the silicone and resin in the house until I'm going to cast, then I set up a little ceramic space heater on the work bench. For the silicone I made a sheet rock lean-to to help keep it warm, so the heater just blows into the small fire resistant box instead of trying to heat the whole garage, an impossible task for the little guy, I thought about just using a cardboard box but was worried it might catch fire. After about 2 hours it is getting tacky then I bring it inside (less chance of it springing a leak on the carpet once it is tacky) where it cures the rest of the way.

For the resin half I just warm the molds in front of the space heater for about 10 minutes while I get everything else ready to go. I shut off the heater while pouring because the fan tends to blow the resin stream around. Once its all poured I start up the heater and go back inside where its warm. I got three sets poured before the resin got chilly and started acting funny (had to give it a little turbo boost with MEK, then it was fine), it was 28 degrees outside last night, not much warmer in the garage. If I hadn't been leaving the resin jugs out there when I came inside I probably could have kept going indefinately.

Anyway its not an ideal set up but it works. Just thought I'd share in case others find themselves in a similar situation. Needless to say I didn't get the giant propane heater for Christmas I asked for.

Edited by Aaronw, 29 December 2007 - 12:40 PM.

[Gregg]

I casted a set of the M/T Big Block valve covers I mastered when it was freezing here, got down to 70, but they turned out okay :-)


Sorry guys, just had to throw that in

I'm packing up the FJ, cooler will be full, and we will be hitting the North Shore for the day on Sunday.....


Should I rub it in some more??????

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[Modelmartin]

Gregg! You poor thing! How DO you survive in those appalling conditions?

And who is the good-looking lady?