First casting..thought(s) on why it failed

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PTJeff

PTJeff

Member
Joined
Jun 13, 2007
Messages
228
Location
Berea, Ohio, USA.
After reading for months i finally got everything set up: HF pot with vac press. It holds either greater than 48 hrs with no significant change. Got alot of help from everyone here at IAP:D


2007103141559_pot-vac2.jpg



Painted tubes white and green. Wanted to make pen for graduating High School senior with label and clear casting.
Used Simlar 41 from popular vendor. I read how most use 3 drops per oz. and followed suit. Math: 5 oz = 15 drops, one more for good measure.
I vac resin for 10 min. to degas (prior to catalyst), bubbles in resin, thought that was strange. Added catalyst, mixed gently but thoroughly. bubbles remain. decided to pour into voids of mold so as not to ruin tubes. Bubbles dissapate, suddenly. Use remainder of pour to cover 3 tubes.
Press it up to 25 lb at 10 pm, get up at 6 am and resin is still liquid. Finally read handout that came with resin, it says 10 drops per oz. i'm a little short.
Finally firmed up at day 10. 2 weeks later this is what it looks like. label lift, paint stripped, still stickey and soft.

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Any thoughts as to why this failed?
 
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Well... I am gonna go out on a limb here, and I am new to casting myself, but maybe not enough catalyst? ;)

If you think about it, you are missing 70% of the catalyst. The lable lift could simply be from long term soaking in the wet resin.


Oh, and in the future, use some junk pen blanks or 3/4" pine "pen blanks" and cut to fill in the extra space in the mold and you could cut your resin in half for the cost of some homemade pine pen blanks.
 
I don't know about that Lee. I cant see a big diff in resins, not that big. 4 drops should have cured the resin. I may suspect the MEKP. Who was the "popular" vendor? Even when I started casting and was carefully adding "3" drops, I didn't have that big of a failure.
The label lift and pealing paint is probably due to the resin staying liquid for so long. It soaked everything for the whole time.
The vacuum and pressure steps sound good, I don't suspect them.
The only time I have had resin that wasn't cured over night was with dark liquid color in it.
Unless you have some strange type of resin (but you said it is silmar 41), I'm at a loss. Maybe someone will have an idea. Cant tell you if MEKP goes bad with time. Resin does, but you would have known if the resin was bad. It starts to gel in the can.
Try a test pour of an ounce or two tonight and see if it cures properly.

Also, let us know which labels and paint you used.
 
Painted tubes white and green.
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For the label lift my money is on the paint. I have yet to discover a paint that does not break down. I will be going to powder coating SOON.

For the cure time I agree with Steve; I suspect the MEKP. If left long enough resin will cure on its own with no catalyst added.

- OR -

Added catalyst, mixed gently but thoroughly.
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How long did you mix the resin? It may not have been thorough enough.
 
How warm was the room you did this in? A cool room will not allow the resin to get warm enough and it will not cure properly. As mentioned old resin will not cure properly and will take a while.

Aren't you supposed to degass after mising in the hardener? Or is there not enough time? It would seem to me that adding in hardener after degassing just adds more air back into the mix.
 
Karl, look up Gadget here on the site. They seem expensive to some, but they are SO worth every penny!! Case in point, I had a tupperware container that was almost 4" wide exactly, but 7.5" long. I placed a pen blank cut up on each end of the cactus I was pourning. I had to mix 20oz of resin and had only enough left to fill one cavity of the purple mold.

I then cut the cactus 3/4" wide and stuffed it into the mold. I mixed 10oz and filled the mold and had enough left over to tint black and pour TWO 6" 3/4" pipe molds!! The savings on wasted resin, and the fact that you have perfect 3/4" (or what size your order) blanks without the need to cut them up (what a mess!!) makes it all worth the cost all day long!
 
Thanks to all that have responded.

I would agree that there needs to be more catalyst, but it will take a few trials to figure out how many is enough. Heating is an interesting concept, especially when a few who do alot of casting, do not even use pressure or vaccume. The way the paint dissolved tells me that the next spare $100 will go to a powder coating unit. The label lift was probably due to all of the errors, too long as liquid which dissolved the adhesive, Avery 5163, which were the "jam free." These jam free versions probably mean a less aggresive adhesive so as not to stick to the printer.

Lee the pine block filler is a great idea, i made the paint stick end blocks to stand off the tubes from the bottom, but one leaked and the level dropped to the top of the tube, so even if the label stuck there was not enough resin to fill.

Steve, I thought the resin was bad so I called the vendor who then referred me to US Composites. Mark was very helpful and we talked at length about the product and its behavior, so from that discussion it was probably not enough catalyst and not enough heat.
Scott, if you ever get a powder coating unit, i'll pay you to practice on a few tubes for me;)
Mikey, i'm a little unsure if you degas before or after the catalyst. When I did this trial, i degassed the resin before the catalyst and there were bubbles in the syrup thick resin, thats why i poured into the voids initially. I didn't want to spoil tubes if the resin was full of bubbles. Then all of a sudden they were floating quickly and popping, heat from the catalyst making the resin thinner? If thats the case i'm trying to degass after the mix.
Ed, wow a trade secret comes forth. Now thats valuable[8D]!
Karl, you have got to get these molds!
Rick, thanks for the help
Lastly thanks again to all that are helping me grow as an artisan

This is my birthday weekend and i may get some good shop time to cast some more. I'll post up my progress
 
Originally posted by PTJeff

Scott, if you ever get a powder coating unit, i'll pay you to practice on a few tubes for me
Click to expand...

I picked up a HF unit yesterday. Let me tell you it isn't as easy as it is made out to be [B)]. There is a steep learning curve. Two coats (and counting) on my first three tubes.
 
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