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slimjerkins
Fireman



Posted - 09/12/2005 :  11:35:57 AM  Show Profile
I tried doing some resin casting for the first time. When I first received the resin (about 4 months ago) I just played around with it by casting a little foundation piece into some clay for a mold. Everything turned out as expected and the resin dried white and hard. BTW I'm using the sutff that has a 7 minute mix time and a 30-40 minute de-mold time. I closed the resin bottles tightly (after squeezing the air out of the bottle) and put them in the fridge.

Well, after making a two part RTV mold I was ready to do some real casting. I mixed up a small batch of resin last night and something went wrong. It seems that this stuff never cured. After a couple of hours I opened up the mold and wiped out the mess that was inside. It just got white and gooey /crunbly.

I cleaned up the mold and tried again. I used an eyed dropper to make sure I had equal amounts of A & B. Same problem this time too.

Did I ruin the resin by keeping it in the fridge? Anyone else have this problem?

Country: USA | Posts: 1320

Rusty Stumps
Fireman



Posted - 09/12/2005 :  12:18:41 PM  Show Profile
Slim, You must absolutely mix Part B well before mixing it with Part A. Then your mixture of Part A to Part B must be exact; 1 to 1. If your mixing small batches you will have a problem as you can't get the two in exact equal proportions, so make the larger batch pouring two or more molds at one time.

Last; make sure that parts A & B are mixed totally before pouring the mixture into the mold. This is very important, scrape the sides and bottom of the container as you mix. This is a leading cause of what you describe, the two parts were not mixed well and so what you had was the raw material. Hope this helps.



Edited by - Rusty Stumps on 09/12/2005 12:22:02 PM

Country: USA | Posts: 7859 Go to Top of Page

Rusty Stumps
Fireman



Posted - 09/12/2005 :  12:18:41 PM  Show Profile
Slim, You must absolutely mix Part B well before mixing it with Part A. Then your mixture of Part A to Part B must be exact; 1 to 1. If your mixing small batches you will have a problem as you can't get the two in exact equal proportions, so make the larger batch pouring two or more molds at one time.

Last; make sure that parts A & B are mixed totally before pouring the mixture into the mold. This is very important, scrape the sides and bottom of the container as you mix. This is a leading cause of what you describe, the two parts were not mixed well and so what you had was the raw material. Hope this helps.



Edited by - Rusty Stumps on 09/12/2005 12:22:02 PM

Country: USA | Posts: 7859 Go to Top of Page

Philip
Fireman

Premium Member

Posted - 09/13/2005 :  07:00:13 AM  Show Profile  Visit Philip's Homepage
Slim,
Just as Walt suggested but also try heating your mold in the microwave oven and let your resin reach room temperature before using it. Resin cures very slowly if cold. A cold mold will also slow the process.

Resin normally has a one year shelf life. If the resin is smooth-on it could be a bad batch as someone was complaining a few months back at the casting forum over on yahoo. Simple a bad batch.

As far as ruining the material from being in the refrigerator. Unlikely unless the resin takes on moisture. You will know if moisture is a concern as the resin will boil over when curing and have a zillion air bubbles.

philip



Country: USA | Posts: 2696 Go to Top of Page

Philip
Fireman

Premium Member

Posted - 09/13/2005 :  07:00:13 AM  Show Profile  Visit Philip's Homepage
Slim,
Just as Walt suggested but also try heating your mold in the microwave oven and let your resin reach room temperature before using it. Resin cures very slowly if cold. A cold mold will also slow the process.

Resin normally has a one year shelf life. If the resin is smooth-on it could be a bad batch as someone was complaining a few months back at the casting forum over on yahoo. Simple a bad batch.

As far as ruining the material from being in the refrigerator. Unlikely unless the resin takes on moisture. You will know if moisture is a concern as the resin will boil over when curing and have a zillion air bubbles.

philip



Country: USA | Posts: 2696 Go to Top of Page

slimjerkins
Fireman



Posted - 09/15/2005 :  09:20:59 AM  Show Profile
After reading the fine print on the bottles I noticed that it DOES say to gently mix the individual bottle contents prior to mixing them together.

I hadn't done this and upon close observation noticed that the bottle contents do need to be mixed up.

Since my two batches were small, I hope that i didn't ruin my resin components by just pouring off the top off the bottle.


Live and learn!



Country: USA | Posts: 1320 Go to Top of Page

slimjerkins
Fireman



Posted - 09/15/2005 :  09:20:59 AM  Show Profile
After reading the fine print on the bottles I noticed that it DOES say to gently mix the individual bottle contents prior to mixing them together.

I hadn't done this and upon close observation noticed that the bottle contents do need to be mixed up.

Since my two batches were small, I hope that i didn't ruin my resin components by just pouring off the top off the bottle.


Live and learn!



Country: USA | Posts: 1320 Go to Top of Page

Mario Rapinett
Fireman



Posted - 09/15/2005 :  09:36:27 AM  Show Profile
Good advice by your mates...mixing is the key.

Not sure why you have resin in the frig......maybe our Oz product is different....

I am interested in your future results..... I luv casting..... ( hate the fishing type )

Mario



Country: Australia | Posts: 5846 Go to Top of Page

Mario Rapinett
Fireman



Posted - 09/15/2005 :  09:36:27 AM  Show Profile
Good advice by your mates...mixing is the key.

Not sure why you have resin in the frig......maybe our Oz product is different....

I am interested in your future results..... I luv casting..... ( hate the fishing type )

Mario



Country: Australia | Posts: 5846 Go to Top of Page

jatravia
Fireman

Premium Member


Posted - 09/15/2005 :  09:53:21 AM  Show Profile
I've not been fishing in a long while ... gotta do that. I also want to try my hand at casting so please keep up the post on your progress. I'll try to learn from everyone elses errors.

Joe <><



Country: USA | Posts: 2831 Go to Top of Page

jatravia
Fireman

Premium Member


Posted - 09/15/2005 :  09:53:21 AM  Show Profile
I've not been fishing in a long while ... gotta do that. I also want to try my hand at casting so please keep up the post on your progress. I'll try to learn from everyone elses errors.

Joe <><



Country: USA | Posts: 2831 Go to Top of Page

wrongsideofthetracks
Crew Chief



Posted - 09/15/2005 :  10:08:37 PM  Show Profile  Visit wrongsideofthetracks's Homepage
Slim - all these comments are very good. I do lots of resin casting as well. I am not sure what is with the fridge, but I don't store my resin in the fridge. Lightly heating up the molds will certainly help and as Walt indicated, getting the proper proportions and mixing them well together is imparative. I mix smaller batches - typically 1 fl oz of A and 1 fl oz of B. I usually stir it for about 20 seconds - make sure you get it well. I always pour A into B. Not sure why - I cannot remember, but that is the way I have done it for years. The resin I use, I never stir up each component separately. Never have - maybe you have some different kind of resin. Thing is you want to keep the air out of - away from the remaining resin as it will degrade when exposed to the air - put the lids back on right away after you get out what you need. I typically start with 12 oz or so of each A and B and then do the smaller measures, then transfer it to another container to mix and pour. Lots of fiddling, but that is what I do. I no longer use Smooth On. I had several poor batches of it - maybe that is what your problem is as well. Last off - don't keep it in the fridge. Normal room temperature is better. Avoid casting if it is cold if you are in the garage or anything like that. Hope that helps you...



Country: Canada | Posts: 940 Go to Top of Page

wrongsideofthetracks
Crew Chief



Posted - 09/15/2005 :  10:08:37 PM  Show Profile  Visit wrongsideofthetracks's Homepage
Slim - all these comments are very good. I do lots of resin casting as well. I am not sure what is with the fridge, but I don't store my resin in the fridge. Lightly heating up the molds will certainly help and as Walt indicated, getting the proper proportions and mixing them well together is imparative. I mix smaller batches - typically 1 fl oz of A and 1 fl oz of B. I usually stir it for about 20 seconds - make sure you get it well. I always pour A into B. Not sure why - I cannot remember, but that is the way I have done it for years. The resin I use, I never stir up each component separately. Never have - maybe you have some different kind of resin. Thing is you want to keep the air out of - away from the remaining resin as it will degrade when exposed to the air - put the lids back on right away after you get out what you need. I typically start with 12 oz or so of each A and B and then do the smaller measures, then transfer it to another container to mix and pour. Lots of fiddling, but that is what I do. I no longer use Smooth On. I had several poor batches of it - maybe that is what your problem is as well. Last off - don't keep it in the fridge. Normal room temperature is better. Avoid casting if it is cold if you are in the garage or anything like that. Hope that helps you...



Country: Canada | Posts: 940 Go to Top of Page

wrongsideofthetracks
Crew Chief



Posted - 09/15/2005 :  10:11:15 PM  Show Profile  Visit wrongsideofthetracks's Homepage
One other thing - when you mix the A and B together - you will start to feel the mixture reacting and heating up. You know it is going to work when you get this reaction. Without using your mold, you might want to try mixing a couple small batches to see if you do indeed have a bad batch.


Country: Canada | Posts: 940 Go to Top of Page

wrongsideofthetracks
Crew Chief



Posted - 09/15/2005 :  10:11:15 PM  Show Profile  Visit wrongsideofthetracks's Homepage
One other thing - when you mix the A and B together - you will start to feel the mixture reacting and heating up. You know it is going to work when you get this reaction. Without using your mold, you might want to try mixing a couple small batches to see if you do indeed have a bad batch.


Country: Canada | Posts: 940 Go to Top of Page

Rusty Stumps
Fireman



Posted - 09/15/2005 :  10:24:30 PM  Show Profile
Cooling part B in the refrigerator is done to slow down the pot life. In hot weather this helps. ALWAYS mix Part A and Part B into a third container at the SAME TIME. These directions are quite explisate on the products I buy which are Alumilite and Smooth-On. Heating the molds helps but I've found not necessary with Smooth-On that much and also in warm weather. Cold molds, under 60 degrees F. must be heated.

I do a lot of casting and I also use micro-balloons on some to get more distance out of the resin. I've built a vibration table out of a heavy duty back massager that helps move the bubbles to the top quite quickly on large castings.

Also, vacuum degassing your mold material, before and after pouring, is a big plus for really good molds that don't have "built in bubbles." Smooth-On recommends this on almost all their silicone mold materials.





Country: USA | Posts: 7859 Go to Top of Page
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