My first Alumilite arrived....

[Russianwolf]

So in addition to having my butt glued to the couch tomorrow, I hope to do some castings that have a chance of working. The resin that I've been playing with just hasn't been up to snuff (I have a blank that I pour three weeks ago that still isn't solid, likely my fault in the mix, but still)

 

[ldb2000]

Remember that the mix of Alumilite is much more critical then PR . You must measure by weight , a simple "that looks about even" won't work consistently if at all and you must get a thorough mix of the two parts , "good enough for government work" won't cut it either . Also try to keep the amount of air that you mix in to a minimum since Alumilite sets allot faster then PR so bubbles won't have a chance to rise to the top .

 

[Russianwolf]

Thanks Butch,
I made my first pour yesterday (about 40 grams or as close as my scale can get). I used PVC for the mold with the tubed blank sitting approx. in the middle. I left it in the shop overnight and went down this afternoon to check. Its hard, but looks white instead of clear, and the surface is tacky yet. I'll wait till tomorrow to remove the PVC/turn round and see what I have, but first impressions are disappointing with the white (this is crystal clear on the label), hopefully its just the ends.

I rubbed the PVC with wax paper as the only mold release, if it works fine, if not I'm not worried about the PVC. The tube has a water slide decal adhered with spray on Elmers.

 

[workinforwood]

It should not be white on the ends, or at least it sure isn't when I pour it clear. The ends should look clear like looking at the edge of a glass table...so it is difficult to see through the end because of the thickness and distance to see through, but clear non the less. Sure should not be tacky...sounds like you did not mix it thoroughly enough. You need to mix it like you are on crack. No need to worry about air bubbles while mixing because the pressure pot will get rid of those bubbles by squeezing them so small you need a microscope to find them. Alumilite requires a 50/50 mix by weight, and the smaller the mix, the more accurate the ratio needs to be, but with 40 grams..if you had 19 of A and 21 of B, it would still work because there is a tiny bit of breathing room in the ratio's.

Casting tubes with Alumilite is not great. You will need to be ultra careful, especially during assembly of the pen. Because the resin is clear, when the tube expands a bit to accommodate parts, it will want to stretch the resin which in turn will seperate the resin from the tubes...that will cause an air spot between the tubes and the resin..not good. Best thing to do is soak ends of blanks with thin CA, then scrape the tube so the parts will not fit so tight into them and use a touch of epoxy to glue in the parts. If the resin was not clear, then none of this would matter because any touch of seperation from tubes on the ends would not be visible.

PR is very hard and does not like to stretch. This is why sometimes PR will crack during assembly if the part does not go straight in or there is some debris in the tubes. This is why PR is better suited for clear cast tubes.

I love Alumilite and it is my favorite casting choice, but it has it's places where it is better suited, such as just plain making pen blanks, casting objects like pine cones, worthless wood, scrolling or segmenting, things like that.

Hope that all helps out Mike.

 

[Russianwolf]

yep, this turned all white on me. I thought I recalled someone else having the same issue, and doing a search found it. The recommendation from Alumilite was to mix larger batches so that the ratio would be easier to hit. My digital scale appears to hit 5 gram increments, so its harder to get the ratio just right in smaller batches.

I'll try again later. Working on something else for now.

 

[Padre]

Mike,
Which Alumilite are you using? There is water clear, crystal clear and also white, tan/black. They didn't mix up your order, did they? I mix mine by the ounce, in 1/10 ounce increments, and sometimes I'm off .3 ounces or so, and it still comes out fine.

yep, this turned all white on me. I thought I recalled someone else having the same issue, and doing a search found it. The recommendation from Alumilite was to mix larger batches so that the ratio would be easier to hit. My digital scale appears to hit 5 gram increments, so its harder to get the ratio just right in smaller batches.

I'll try again later. Working on something else for now.

 

[Russianwolf]

label says Crystal Clear. but I found a thread from a while back where the person had the exact same problem and was trying to mix small batches like I did, advice from Alumilite was to increase the batch size so that being a little off in the ratio wouldn't be as critical. That solved his problem and that's what I'll try doing also.

Mixing may have been a problem too.

 

[workinforwood]

I mix colors totally as small as .4 on my scale, I assume that is .4 ounces or 40 grams and it works out just fine. It takes 3-4 ounces to make a pen blank dependent on the size of the blank of course..but that is about the average total resin use. I do not mix .4 in clear though because I generally add colors, so that could be an issue for clear blanks, but even so, it should harden up just fine although it will take much longer for that small of an amount to cure. You need some volume to generate good heat for a fast cure.

 

[Russianwolf]

my scales increments are .2oz or 5 grams. anything finer than that is a guess. For example a AA battery on my scale reads 25g or .8 oz. But the actual weight may be a bit more like 23g or .75oz and I wouldn't know it. In small batches the amount you are off would be a greater percentage than in a larger batch. If you are off by 3 grams at 40, it's nearly 10 percent. 3 grams at 400, not even 1 %.

The batch I made for yesterday was two tubed blanks. With the tubes in place, the 3/4 inch PVC as the mold and all The 40 grams I measured out was more than I needed and is a good bit less than 2 ounces.

What all this means is that I need to be ready to cast more blanks at one time, or be ready to waste some resin.

 

[workinforwood]

You need to document your pours. Eventually all your pours will become standard, like perhaps you will be using 1" pvc at 5" long as one standard, and 5x5x7/8 silicone molds as another standard, etc, and you will be able to just peak at your chart and know exactly how much resin you need for each standard type of pour you do. I have a list of all my molds because resin isn't cheap. I always mix a little bit extra regardless, just to be safe, but that is exactly that..just a LITTLE bit.

 

[MesquiteMan]

Mike,

If you haven't already, I highly suggest you go out and buy some clear plastic cups from Sams or Costco. The reason to mix in clear cups is because when you pour in part A and part B, it will be cloudy and streaky. Mix completely using a rubber kitchen spatula, scraping the sides and bottom as you go. Keep mixing until 100% of the streaks and cloudiness have gone away. Don't rush it. You have WAY more time than you think!