Alumilite is turning out brittle

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Thread: Alumilite is turning out brittle

  1. #11
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    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?


     
     
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  3. #12
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    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

     
     
  4. #13
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    Maybe your scales gave a false reading.

     
     
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  6. #14
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    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

     
     
  7. #15
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    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.

     
     
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  9. #16
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    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
    P8060639.jpg

     
     
  10. #17
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    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
    If you think my photo is upside down that's because I'm from the land down under !!

     
     
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  12. #18
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    Yes, I agree, I'd try curing in a warm room (around 23 degrees), but with no additional heat.

     
     
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  14. #19
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    Quote Originally Posted by fingwe View Post
    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
    "Top Turner" ~ Yeh right!!!

    I ask the daft questions ...so others don't have to..

     
     
  15. #20
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    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
    P8070642.jpg

     
     

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