Observations about Alumilite White and Foams

[aka anglinarcher]

I think you might find the following observations useful. If your results differ from mine, please comment in this thread.

I have had the pleasure to do density testing on Alumilite White, 610 foam, and Super Foam 320. Frankly, I have probably done too much, and got far too deep into it. After all, the alternative, wood, is not as consistent as any of these, so the results I will be offering soon are going to be far more reproducible then any wood product. Still, I offer these results for your consideration and possible use.

My first tests were done on Alumilite White. This product can be mixed either with equal volumes of Part A and Part B, or by equal weights of Part A and Part B. My test shows that both create perfect results; strong, consistent, excellent.

I did notice that Part B is slightly heavier (denser) per unit volume then Part A. What this means is that if you measure by weight, and not volume, you will end up with a little of Part B left over at the end of the bottle.

I also noticed that this means that if you test the density of the two mixes, the equal volume mix is slightly denser then the equal weight mix. The difference is so little that it is hardly worth mentioning, but some of us are working on suspending baits so you should be consistent in which method you use. Also, the measuring cups that are disposable are not marked with as small a unit as you can get if you use weight, so, in short, I suggest that for greater reproducibility, the use of a scale is best. A scale that measures down to 0.1 grams works well. Keep in mind that most of us really don’t need that kind of accuracy and the plastic works well either way.

I also noticed an additional factor. For my testing, I used a 5/8” diameter wood dowel to make a mold. I made the mold 4” tall. The reason is that as we mix the two parts together, we introduce bubbles. These bubbles do not have time to escape before the plastic sets up, but they do rise, so the density of the plastic at the bottom of the mold proved slightly greater than the plastic at the top of the mold.

OK, we are talking differences, so now I need to give the differences. With equal parts, by volume, of part A and part B, with no micro balloons, you get no expansion of the plastic as it cures, and the density of the bottom half is 1.09 grams/cubic centimeter. The density of the top half is 1.08 g/cc.

If we mix equal volumes of Part A and part B, with no micro balloons, by weight this time, the density at the bottom is 1.08 g/cc and the density at the top is 1.07 g/cc. Again, you get no expansion.

With so little difference, you might as well consider there to be no difference, but all of my test will now use equal parts, by weight, for the test. Notice that with no micro balloons, the density of Alumilite White is 7% greater than water, without hooks, eyes, hangers, etc.

OK, enough for now, I continue with Alumilite White using Micro Balloons next.

[Mike - Alumilite]

Great info!

[aka anglinarcher]

Thanks Mike, I am working on a graph on AutoCAD now.

[aka anglinarcher]

Sorry I have not get back sooner, but let me add a little to this thread.

As mentioned, my test used equal parts A and B by weight, but I thought you might like to know that the two parts are not the same density.

Alumilite White Part A is 1.11 Cubic Centimeters per gram or .9 g/cc. Part B is 1.07 Cubic Centimeters per gram or .93 g/cc. I hope this helps you in your pouring.

I measured the microballons by volume because they are so light. For the dedicated, 7.5 cubic centimeters is only 1 gram.

More info to come later.

[aka anglinarcher]

Let's side track a little now. For the Record, Balsa wood is a common lure making material. It is light, but not that strong. Still, it is a standard. My test showed that my balsa came out to .18 grams/cubic centimeter. Notice that this is about 18% the density of water.

I know of lot of us have used Cedar Wood, and Alaskan Yellow Cedar is one I could test. It turns out that the Cedar wood density was .47 g/cc or 47% as dense as water.

Alumilite makes a product known as 610 Foam. This stuff is pretty cool. It is a foam, and you need to follow the instructions to allow for expansion, but, inside the mold where it is constrained somewhat, it forms a skin that is pretty smooth, as strong as Balsa, and about the same density. My test show the density of 610 Foam is .24 g/cc. It should be noted that the foam that was not constrained and expanded out of the mold was even less dense, but just as strong. It tested only .15 g/cc, Now keep in mind that this unconstrained material did not have a smooth surface, but on an open face mold it might make a material much less dense then Balsa. It bares some investigation.

Alumilite has another foam, Super Foam 320. This stuff is not strong at all, but it makes a super light structural filler for hollow baits. Constrained in a mold, it has a density of only .07 grams per cubic centimeter; now that is pretty light, and far lighter than any wood. The unconstrained is .05 g/cc, so I would stick with the constrained form of it. Like the 610, it needs to have room to expand (up to 20 times) and a hole to expand from.

In correspondence with Larry Dahlberg, he mentioned that the 610 Foam sticks to the Alumilite White well. Larry has a taste for understatement. I allowed it to over flow into a glass measuring beaker I had and it stuck like it was part of the beaker. To remove it, I soaked the foam in MEK (those that know about this stuff would tell you not to fool with it, but I am not smart enough to leave well enough alone ) and then it finally came off. Larry mentioned that he was working on hybrid lures using Alumilite White on the bottom and 610 Foam on top, so now his secret is out. Sorry Larry.

[aka anglinarcher]

I hope the following information will be of use to you; the density of Alumilite White with different amounts of microballons.

I tested several runs of Alumilite White with differing amounts of microballons, to help myself, and perhaps you, to determine how dense each amount of microballons would make the end product. The first bit of information that might be noted is that adding microballons will cause the product to expand a little. Leave a little expansion room at the pour hole and in air holes to allow this small amount of expansion, but fill the mold up with the mixed product.

The mix percentages are best described as percentage of microballons added to the mix. For example, 20% microballons would mean that for every 100 cubic centimeters of Alumilite White, you would add 20 cubic centimeters of microballons. Or in other words, for every 10 cc of Alumilite White, you would add 2 cc of microballons. The instructions say you can mix up to 100% microballons (100 cc Alumilite mix and 100 cc microballons). In the test below, the 92% was almost the thickness of “half and half”, the stuff a lot of you mix into your coffee.

Based on equal parts 1 and parts 2 by weight (converted to volume), and then adding equal microballons by volume.

% microballons ----- Density in g/cc

0 ------ 1.07
22 ------ .91
25 (predicted) ------ .89
46 ----- .79
50 (predicted) ----- .775
66 ----- .74
75 (predicted) ----- .72
92 ----- .69
100 (predicted) ----- .678

Depending on how you graph this, it is almost, but not quite, a straight line. In fact, it is a power curve. I suspect that it is due to the expansion created when you add the microballons. Still, for the mathematically inclined, the equation that comes closest to this graph is:

1.6469* X^-.19248 = Y, X is the variable that is the percentage of microballons. Y is the density of the end product.

I have graphed it using a method to expand the coordinates and make it easier to predict what you will get. There is no real way to post it here, so I will try to post it in the lure section. Notice that due to the coordinate expansion you can actually see the curve. This graph will get you closer then the approximate equation that is above.

Final Notes:

1) Just because you cannot get exact with the equation, or the curve, does not mean the product is not predictable. In fact, it is far more predictable then wood. Wood density will differ from climate to climate, from year of growth to year of growth, and from location to location. The Alumilite will be very “repeatable” from batch to batch.
2) The densities do not account for the weight of hooks, hook hanger, ballast, paint, finish, eyes, etc. Mike told me that usually a mix of 20% to 25% will give you neutral density in most cases, but this really depends on how you design your lures.
3) If requested, I can provide a method of using buoyancy to test your master and determine what density you need, but this is another topic completely.