Alumilite not curing?

[bgio13]

Well its been over a week now so I decided to see how my first casts with Alumilite turned out. I didn't have the Alumilite dyes so I used some of the PR dyes to see if they work, and also cast a clear blank. I did the fingernail test on the edge of the blank and they seemed like they were good and hard. After drilling a couple of blanks I noticed the shavings were really soft and pliable, not really what I am used to when I drilled Eugenes blanks. After about an hour I cleaned up the drill press and noticed the shaving had hardened up. What I was wondering is does this mean the blanks are not fully cured and if so how long should they cure for, or does drilling the blanks help them cure faster, thanks. Forgot to mention that my basement is around 55-60 degrees. Is this too cold for Alumilite to cure?

Bill

 

[dasimm]

Hi Bill,

The temperature should not be a factor - I have cast in similar conditions with no problem. The curing process does create a small amount of heat.

As you are probably already aware, the Alumilite resin parts absolutely must be mixed "really-really-really" well before pouring them into the mold. Also, the two resins have to be as close as possible to equal parts. I found that measuring in grams helps get an exact ratio of 1:1 and I usually have little issues with it curing.

FWIW - I believe your Alumilite is probably still in the curing process - the heat generated from the drill probably accelerated the curing time which is why the shavings from the drill press felt harder after a few minutes.

Some casters here on the IAP will heat (@ low temps) the casting after the PV to accelerate this curing time. I do not - I simply leave mine for about 24 hrs before cutting or drilling on it - sometimes it's longer but always at least 1 day. Thats my preference and not a hard-fast rule.

Hope this helps

 

[baker4456]

I have an old refridgerator that I put a small space heater in to help my resins cure after the pressurization. I also use it for a drying cabnet

 

[fiferb]

Something else that may have happened to get the soft shavings when drilling is you let the drill bit and blank get too hot. This will melt the Alumilite as you drill. This could also account for it getting hard after it cooled.

 

[ElMostro]

Hmm…the only time I had something similar happen was
1) when I mixed part A from clear alumilite with a part B from the white alumilite
2) and when my scale was off and I put about 1 ounce of one part too much
3) once I got lazy during mixing and did not mix completely
4) I tried a very thin layer (1/8" thick) ...it eventually cured but the next day it was still flexible
5) I tried to mix ½ ounce of each to fix some blanks and that mix took a while to harden…maybe bec the small amount did not produce enough heat

Properly mixed alumilite should be more than cured in a couple of hours…I usually pull mine out in about 3 hours and as you know I put some weird stuff in the casts. If you measured by weight and used the part A & B of the type of alumilite and mixed well then the only other thing is the dyes may have reacted (I use trans tint from woodcraft and it slows the curing a bit so I leave the blanks under pressure overnight). Try putting the blanks in a toaster oven for a while at about 150 degrees (not a microwave) and then see if they get any harder.

Eugene

 

[workinforwood]

Sounds close to normal to me. Sounds like the bit got a bit hot is all. Alumilite doesn't melt, but it will get soft with heat and re-harden when it cools down. So get spinning it. It'll spin different than PR of course.

 

[JAG]

I have had this same problem with mine. Cast them hard as a rock drill good but when I turn them down I can squeeze it like a sponge. Put on the shelf in a couple of days it hard cant figure it out. my blanks I make are 1.5 inch by 1.5 inch and 3 inches long. The first 10 blanks IU made I didnt have a problem now that all I have is problems.

 

[NewLondon88]

Is the clear blank doing this too? I could understand if the wrong dyes caused the
problem, but the clear blank shouldn't be an issue..

 

[JAG]

Mine was clear

 

[mostangrypirate]

i agree with those who say it was caused by heat. this stuff is basicly plastic. it will probably melt even catch fire if you apply flame. stands to reason that it will at least soften under intense fricion. my PR blanks do the same thing and I have never had a problem.

 

[Glass Scratcher]

Not all Polyester Resin pigments are compatible with Polyeurethane resins (Alumilite) and not all Polyeurethane resin pigments are compatible with Polyester resins.

Did the pigment you used state that it was compatible with Polyeurethan resins?

 

[td]

By

Where resins are concerned there is nothing "basic" about it. The chemical process that happens while curing polyurethanes is different than the polyester resins, although both go through an exothermic reaction. This is why they have different shrinkage rates and why not all dyes and coloring agents used are compatible. By the same token there are literally 100's of formulas of polyester resins and polyurethane resins on the market. Print off your MSDS's and know what you're working with.

 

[bgio13]

I decided to turn one of blanks I cast the other day and had the same thing happen as Jag. The blank was rock hard on the outside but I could squeeze it after turning the blank round. It was so soft that instead of nice ribbons or some sort of chips coming off the skew, I was getting white dust. These were the clear blanks with the tubes and hole painted. I set the blank aside for the day and came back to it. It was hard as a rock again. So I turned it down to the bushings and started to sand with 400 grit. When I sand I move the paper pretty fast and don't let it it in one spot, and only leave it on the blank for a few seconds at a time. A I was working my way down the blank I noticed the blank looked like it was wobbling from being out of round. I stopped the lathe and there was a bump at the end of the blank. It looked like I pushed some of the material to one end. There was even a void where the bump was. I tried to see if I could push the material down and just peeled the material from the blank it was so soft. I have turned blanks from Curtis and Eugene and have never seen this before. Sorry for being so long winded but I did not take a picture as it went right in the trash. The blank cured for about two week before I tried turning it so I have no idea happened besides heat building up. I just don't remember having to worry about heat when turning Eugenes blank. Thanks, Bill.

 

[WoodWizard]

could it be a bad batch of resin? I have no clue...but it almost sounds like a bad batch of something...hope you get it worked out