Alumilite and Cholla

[woodgraver]

I have done a little bit of research on here about casting cholla and done a few successfully using Silmar 41. I love the way Curtis' blanks turn though and after watching his videos I thought I would give Alumilite a try. I first used some Alumilite regular just because I had some available locally. It turns tan when cured so it is hard to get the color you want...the red cholla pictured is colored with red Alumilite reactive dye and still looks a little on the hot pink side.

I did get an order of Alumilite water clear in though and decided to give that a try. I used the same reactive dye and put some mica powder in it too. I measured both a and b parts on a scale. Mixed them together thoroughly, then added the dye and mica. I immediately poured the mixture into a cholla cactus wrapped in masking tape and used my HF pressure pot at 40 lbs for 1 hour...in a cold garage. Now maybe this is the problem, but I cast the Alumilite Regular under the exact same conditions.

Anyway, as you can see there are many bubbles in the green cholla blank. Now I was thinking moisture, but the left over resin I mixed I put in a small container and into the pressure pot at the exact same time and it has the same bubbles. I did try to dry a piece of cholla in my toaster oven at 150 but it nearly caught fire. Not sure if the thermostat is broken...I'll need to get a thermometer before I try that again.

Any other thoughts on this? Would I have had better luck if I had used the double cup hot bath method with the Alumilite like we do with PR?

Thanks for any insight! I only have 17 more of these to make and once that order is complete, I will try and find some other canvas to use! :)

Jim

[OKLAHOMAN]

Jim, I just sent you a pm. I really think its not enough pressure that has cause your problem. I had the same problem and increased the pressure from what I normally cast PR 35 PSI to 70PSI and it seems to work getting it flowing into all crevasses. Haveing never used regular and only water clear you also need it bone dry, I place in my toaster oven at 145 for at least an hour before casting. Hope this helps.. Roy

[maxman400]

Originally Posted by woodgraver

I used the same reactive dye and put some mica powder in it too. I measured both a and b parts on a scale. Mixed them together thoroughly, then added the dye and mica.

Jim

Jim it is my understanding that the dyes are suspended in "PART A" so you can add your dyes and powder to part "A" and mix them ALL DAY if you want to, to get a good mix with no clumps of powder. Alumilite is very thin and as such I believe it soaks in to the wood which disperses the air in the wood. I have had good results with treating the cholla with a wood stabilizer first, and I also cast mine at 60 lbs of pressure.

[TomW]

My money is on moisture in the green mica powder. Powders have a real affinity to moisture. You should dry the powder the same as drying the cholla.

Tom

[woodgraver]

Interesting feedback...never thought about the mica powder having moisture in it...but I used some with the Alumilite Regular and had no problems. I did notice they mixed the dye in part A but I didn't associate that as a critical step...I think Curtis' video showed mixing the dye after so you could be sure you had mixed A and B totally before you added the dye. I have a HF pressure pot, so going up to 60 PSI scares me...but I think I can use my compressor regulator and stay in another room while I pressurize it ;) I'm going to try another one with no mica and mixing the reactive dye in the "A" part...I'll report back, but if you don't hear from me...please warn others about HF Pressure Pots! :) I really want to get a bigger pot with a higher pressure rating, but so far I haven't found the "perfect" one. I did try to research a chamber to allow me to dye wood at 5,000 psi...they only wanted 10 to 15 thousand for it!

[doddman70]

When casting with a powder in alumilite I always put my powder in a small metal cup and place it in the toaster oven with my cactus,

[soligen]

Could be moisture, or If your garage is cold, you may need more time .. and pressure. I only used Alumilite a couple times, but I had some worthless wood blanks with bubbles because the resin was not quite cured enough and air came back out of the wood to make the bubbles. More time fixed it. (Was cast at 80 lbs)

[tkbarron]

I'd steer clear of Alumilite Regular and Water Clear. Regular cures way too fast for a decent mold and certainly way to fast for a pressure pot to do it's job. Water Clear doesn't like like the heat when turning or sanding. It will gum up on you.

Give Alumilite Clear a try. It works wonderfully for me.

Tom