first pressure casting, a BUST!

[elody21]

Well my husband and I finally got everything together and I got time on my schedule to mess with casting resin. I have done MANY MANY castings without the pot. I thought I would be real smart and try a loofa sponge similar to the catcus casting. Well after an hour in the pot the resin did not set up at all! Completely liquid! I used 5 drops per ounce. All I can think of is there is something on the loofa sponge that messed with the resin. OR does resin or fixer go bad? I would think 40 pounds pressure for an hour would be plenty of time.The resin etc... has been stored in the basement for a year. I actually poured the resin back out and added fixer from a new bottle and I have it in the pot now. I don't expect too much but after all of the work cutting up the loofa I wanted to give it one more try. does anyone know how to get liquid resim out of a loofa? I will probably just throw it away. Bummer!

Well I will let you know the outcome. I hope the resin is still good. I still have a half of a gallon left! alice

 

[Dario]

Why not test a small amount of the resin without the Loofah and see if it will set?

 

[JimGo]

Alice, just be patient; it WILL set (eventually), but you'll want to keep the pressure on longer.

 

[Lornek8]

In my experience, resin can go bad, especially if subjected to high humidity, as in opening and closing the container frequently during periods of high humidity. What typically happens to me is that the resin takes longer to cure. Typically I shoot for about a 10 minute gel time from my mix (with fresh resin). With older resin, using the same ratios, I have had resin sit for over 20 minutes before beginning to gel. What typically happens is that I get impatient and after the first pour add larger quantities of catalyst to subsequent pours. When the resin finally begins to harden, the excess catalyst causes the resin to get too hot and I end up cracking the resin. The real problem with old resin is that it often not predictable and your old mixtures may not work the same. If you purchase large amounts of resin that you are not able to pour in a reasonable amount of time, you may want to pour the resin into a smaller container from which you do your casting. That way, the large container is not constantly being opened and closed all the time.
To clean the loofa, try soaking it in Acetone (for polyester resin) or whatever you use to clean up the resin. I am not sure what it will do to the loofa but it is worth a try.
Good Luck,
Lorne

 

[elody21]

Thanks guys.
I will try a small amount.
The second try is still in the pressure pot. I am afraid to open it.
Is it the resin or the activator that goes bad? It was kept in the basement which has a dehumdifier going all of the time.
I should have started with something simple, but I thought this was! Mix the resin,color and pour. I am thinking maybe I put too much colorant in it. The color is black in a paste form for resin but I did add a lot. I wanted it very black.
I am not sure if I will mess cleaning up the loofah. Too much mess. Oh well
Alice

 

[Dario]

The color might have caused the problem.

Note that the nice deep looking cactus pens were casted clear...they just colored the hole or tube (black, blue, red, etc.) FYI, just in case you missed those.

 

[Draken]

I did some casting over the weekend, and after a few hours, no heat at all, meaning it wasn't settnig. Fired up the oven, preheated to 170, the TURNED THE OVEN OFF. Placed my trays of PR on a cookie sheet covered in foil, and placed in the oven. A few hours later, everything was nice and set. Haven't seen any cracking when removing them from the molds, and drilled out a few without problems, so looks like everything came out okay.

I think my problem was switching from one dispenser of catalyst to a new one. Seems the drops are much smaller, throwing off the ratio. Next time I cast I'll double the number of drops, should make up for their smaller size.

Cheers,
Draken

 

[elody21]

Well, the great loofah experiment is tried,failed and DONE! The second try did not work either.
I made another blank ( just plain)with a new bottle of activator and everything went ok. I did not put it in the pot because I still had the other blanks in there.
So the problem was either too much color, the loofah, or the old activator. I will never know because I do not plan on trying it again!
With all of the time and pressure on the blanks the duct tape on the bottom had come apart and the STILL liquid resin leaked all over the wooden insert I made. What a mess.
I will try the pot again but on a different kind of blank.
well, wish me good luck on my next try! Alice

 

[elody21]

Originally posted by Dario
<br />The color might have caused the problem.

Note that the nice deep looking cactus pens were casted clear...they just colored the hole or tube (black, blue, red, etc.) FYI, just in case you missed those.

I sure did miss this. I thought the resin was colored!

 

[Lornek8]

It is the resin that goes bad. Once the can has been opened and exposed to humidity it doesn't matter much where you store it as the moisture is already sealed in the can. If you open the can in a dehumidified or low humidity environment then you don't really need to worry as much. Just a warning, you probalby know this already anyway, but be sure you pour the resin in a well ventilated area. The fumes from the resin is toxic and has a cummulative effect.
Black pigment(opaque) can cause problems with resin hardening, especially in large quantities. When I cast using black pigment, I simply dip a popsicle stick, vertically, app. 1/4" into the paste and pull it straight back out. That is usually enough for a 1 ounce pour. Typically, even with this small amount I can double the amount of catalyst I add and the resin still takes longer to set. Do a test with unpigmented resin to see if it was the pigment that created teh problem.
Regards,
Lorne

 

[elody21]

Lorne,
Thanks for the response. The resin seems to be working fine with the other casts I did today. It was probably the black paste colorant.
I do all my casting out on the back porch. I also wear an OSHA mask for fumes and gloves. My husband got me a hundred feet of air compressor hose so I could run it from the basement to the porch for my pressure pot. So I can only do casting when the weather is nice.
Thanks again everyone for the suggestions and ideas of what went wrong.
Alice

 

[MesquiteMan]

Originally posted by elody21
<br />

Originally posted by Dario
<br />The color might have caused the problem.

Note that the nice deep looking cactus pens were casted clear...they just colored the hole or tube (black, blue, red, etc.) FYI, just in case you missed those.

I sure did miss this. I thought the resin was colored!

It depends on the look you are after. The very first cactus pen I posted on the net was with the resin colored. The nice black baron cactus pen is with black resin. Clear resin with painted tubes gives a different effect, more of a 3-d look. With the clear resin and painted tubes, bubble free casting is much more critical than with colored resin.

 

[alamocdc]

Alice, maybe it's just me, but the only time I've had resin set up within an hour I could turn it in 4. And boy was it brittle... and full of bubbles! I use 5 drops per ounce and I'm lucky if it gels in 3 to 4 hours, so I just thought that was how long it was supposed to take. I'm working on getting my pot rigged now and plan to leave the blanks casting under pressure over night 'cause I don't wanna take no chances.

 

[JimGo]

Alice,
Too much color will SIGNIFICANTLY increase the cure time. The trick is to add just enough coloring agent to get you the color you want. Any more, and the blanks will be rubbery for weeks! Not that I have ever had this happen to me or anything.[:I]

Oh, try wiping the blanks with acetone, or putting some acetone on top of the castings. That may help with the curing.

 

[elody21]

Well. It is morning and I am rested. I plan on trying to save the loofah blanks at least one more time. I'll try the acetone and see what happens. I probably should let them air dry for a day outside to let the acetone evaporate before trying the resin on them again. I think this time I will try clear resin and just paint the tubes! Man for what I thought was a good idea I have really made a mess! I hope I am not the only one that does stuff like this! Alice

 

[elody21]

Up Date! Well Jim you were right what did not leak out of the mold DID harden! Although it is very sticky. So I think I will wrap it up again and try to fill the remainder of the space with black( only a little of color) or maybe claear and see what happens. Alice