Alumilite is turning out brittle

[jas46]

About a week ago I thought I'd try alumilite resin instead of my normal opticast 100
Now at first I thought everything was much better with the alumilite resin but now as I'm ramping up too what I do with the opticast100 I'm finding the alumilite is very very brittle, I had a pen blank crack and split an inch section off the blank whilst I was drilling with very little pressure I might add.....
when I was lathing the stock round the chips where flying like they where splitting not shaving, I had the chisel dig in twice and it obliterated that section it was almost like it was chipping the resin not shaving it it left holes that had definitely been snapped rather than shaved off this was with a round bit very sharp chisel

The best way I can describe it is , it has the same property's as polyester resin I even smacked some with a hammer and it shattered but the opticast stayed in one piece. ..

The measurements where done by weight and a 100 gram pour both from what I remember where correct but it's not just a one off every pour is the same time, it's under 50psi for about an hour and heated in oven for an hour at 45c the left for a day to fully cure.

Has anyone had any problems like this with alumilite resin and what could cause this?
Or is this how alumilite is supposed to be

Thanks
Jas

 

[Penpal]

Had the problem with bought ones also the earlier ones discoloured in storage.

Peter.

 

[jas46]

Any idea of how to get it sorted penpal I've got 7ltrs of it lol and don't want to use it until I know why it's doing it
Jas

 

[fingwe]

Hmmm, that doesn't sound promising.....I've never had those kinds of issues with any of the polyurethane resins I've tried. I've not had a chance to try Alumilite yet, but I was expecting it to be similar to other polyurethanes. I know that Alumilite did change the formula of 'normal' polyurethane resin to make it slightly harder and easier to polish, but I wouldn't expect it to do what you're describing. Maybe contact Alumilite in the US, and see what they suggest?

 

[jas46]

Fingwe I know I was expecting it to similar to the opticast, I have no doubt that's it's something I've done it's just figuring out what lol
I have emailed them and awaiting there reply but I'm not sure how long metal clay has had this as it was on there special deal and this stuff only has a 3 month shelf life
But I did make a 4 blank slab this afternoon which the bandsaw cut with no problems, I've just got see how it is when I lathe it down

 

[fingwe]

I don't think metal clay have had it in stock long, so it shouldn't be out of date. You could also try asking on penturners.org as there will probably be a lot more people on there who are experienced in casting alumilite.

 

[Penpal]

I bought 12 or so blanks in Aluminite that crazed in turning, able to save them but a nightmare cutting frugally. Early days I had a mate in the states who used the material when snakeskin was new to pens most all the early ones went yellow in my stash.

Peter.

 

[Penpal]

Sorry the only pic I took of a crazed blank of Aluminite I knocked the Auto to Manual, the recovered blank is on this pen. Three more of them. They are butt clenching slow to work with.

Peter.

 

[jas46]

Fingwe, that's good to know I don't think it's the resin I think it's something I did I have been reading that alumilite does take days to fully cure and is more brittle than I'm used too but this I would rank aside polyester resin if not worse which makes me think I've done something wrong somewhere along the lines
I did a slab yesterday and it has cured up perfect now it's just a waiting game to see how it lathes up
Penpal
That is the same as what mine did and good save the finished pens look cracking mate, mine split when I was drilling it took a big chunk out so I have no choice but to launch the remaining bit at the shed wall .....shattered into pieces lol

 

[wm460]

I have had a few like Peters.

 

[21William]

I've not cast any pen blanks but I have laminated items in the past using epoxy and polyester resins and not found either to be particularly brittle. In fact probably the hardest was the epoxy (Wests) but then I was heat treating it for maximum strength. From what some folks have said on here about polyurethane resin it doesn't sound like something I'd be tempted to use or am I missing something. Is it really cheap?

 

[jas46]

21william
Polyurethane resin is normally very good the opticast 100 i normaly use is brilliant stuff, I've thrown a blank at the floor and it bounced back up with only a dent lmao but for me it's this alumilte formula I'm doing something different or wrong that is making it brittle ...just need to find out what lol

I personally use polyurethane over polyester and epoxy dye to the smell and curing times but each resin has its uses the only one I've yet to try is epoxy...

Jas

 

[Paul hd]

Maybe your scales gave a false reading.

 

[jas46]

Could be Paul, but am still not 100 % sure I put the same amounts ...I'm always question myself lol
They should be good scales nearly brand new and I use them for the opticast 100 ...
I did drain a shed load of water from the compressor trying to figure out what could have done it but water would make it bubble ...yet the blank looked perfect...
I'm going to lathe the blanks I made tomorrow to see how they are I know with these that the measurements where bang on lol so fingers crossed they turn OK

 

[fingwe]

Yes, if moisture was in your mixture then it would have foamed.

It is a little worrying that others seem to have experienced the sames issues with Alumilite blanks they have bought. To me it suggests that it has very exact parameters to cure correctly. If this is the case, it is much more trouble than any of the 4 or 5 polyurethanes I have tried so far - the only issue I've ever had was when I tried curing in a cooler room than suggested - and that just shrunk a little at the corners and took longer to cure, no issues with brittleness.

 

[jas46]

i agree i bought the alumilite as i heard good things its supposed to cut like butter polishes up better and to be fair it does polish up so much better than the opticast100

i lathed down 2 of the blanks i made after the bad one and they where so much better i got chips flying as the corners were being lathed down but that was expected
i only had the dreaded dig in once on two blanks but i was taking more care this time.
From what i have been reading Alumilite clear has been made to be more brittle than our opticast so that it easier to polish up and give the end user a higher polished product ...and it is a lot quicker to polish up and a better finish over the opticast
its almost like the alumilte is in between polyurethane resin and polyester resin to try and get the best of both
the attached pic is the blanks i made friday and lathed from alumilite today its just had 2 buffing wheels to polish half up

 

[Goggomobile]

Jas,
I've only just started using Aluminite Clear. I read a lot of US posts and Utubes. This is a list of things ... many probably are irrelevant but might trigger something in the grey matter ... most relate to moisture. I'm in the sub tropics-ish so humidity is always highish .. not like Darwin though.

- Aluminite hates moisture
- 6 month life
- once seal broken can absorb moisture ( may vary with humidity)
- store resins in a stable place
- can pull moisture from cups, pigments, and micas if not dry
- ditto for moulds
- ditto for air in compressor
- moisture comes out of air under compression
- compressed air is cool when it comes out and can creates vapour
- Part A Goes gluggy after 6 months, hard to pour( personal experience)
- resin might interact with other materials
- resin might interact with other chemicals, oils and waxes
- make sure barrels are clean
- shrinkage ? Not sure

While there is plenty on moisture I don't think that is your issue. Other ideas

- age of batch
- mixed batch .. there are other Aluminite Urethanes which are harder (most not Clear though)
- pressure in pot needs to be higher eg 50psi .. make smaller bubbles maybe less bubbles
- leave in for 2 hours ?
- heat cure to accelerate cure might cause brittleness or heat to high or for too long
- try no heat cure just natural

Randal

 

[fingwe]

Yes, I agree, I'd try curing in a warm room (around 23 degrees), but with no additional heat.

 

[KevinMc]

Yes, I agree, I'd try curing in a warm room (around 23 degrees), but with no additional heat.

Well you would wait a long time to find a room like that naturally here in Tyne and Wear

Kevin

 

[jas46]

Thanks for the list Randal
I have the pumps on both my containers but this happened with the first batch that was made and both where sealed
Pressure wise I can go upto 60psi and will give it a go I have read though that high pressures can cause problems lol
The next batch I am going to leave for longer in the pot but it is solid after the hour
I actually thought the post cure might have effected the brittleness so the last slab I made I never post cured it and although when I lathe it down it never chipped well once I knew it would do if I pushed hard.
The one thing it might be as you've said is the mold, the one that was brittleI poured in a mold made from that putty silicon mix for molds and it was an old mold that's been sat around for ages, the second slab was into my hdpe mold....
The funny thing is if I lathe a small inch section and curve the chisel I can take one hell of a cut, but if I try a sweep cut that's when it goes wrong and digs in chunking the blank.....
It could be that is just how alumilite is and I've got to get used to it, but I can't sell my blanks unless I'm 100% sure
The weird thing is everything else is perfect they gel fine, cure fine and polish beautifully it's just lathing that's the problem...

I hear you on that Kevin I've got an oil heater in my shed to get the temp's up lol then the blanks come in the house but even then it's only 17 in there
This ia what i made today from the last alumilite blank