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Casting resins

Tephy

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Oct 14, 2014
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Steve
Hi
having seen many questions about casting resins I thought it might be nice to give a general guide to the four most popular resins.

POLYESTER RESIN

I think this is the one we all know, a cheap mostly clear resin. It is slow setting and stinks like hell, I use it outside as I do wonder if the fumes are toxic . Manufactures do state use in a well ventilated area. It is described as hard and chippy/brittle when turning ( often will chip or break when dropped ) , however fast lathe speed and good sharp tools tend to get around the problem.

EPOXY RESIN

It is expensive compared to other resins. Often used with fibreglass for repairs on boats, Robin reliant cars and Kit cars and similar. Again a slow setting resin like Polyester but without the smell. Good as a glue. Sets hard so would follow turning guide for Polyester resin.

POLYURETHANE RESIN

Manufactured in USA by a company called Alumilite. Polyurethane is softer than the above resins so no chip outs as such, also there is no smell and is readily available in the UK from various manufacturers. It is a fast cure resin, going from casting to turning on a lathe in 1hour. BUT due to the fast cure it tends to trap bubbles and so needs to be used with a pressure pot, it has been said to me to vibrate or use a vacuum chamber, even with what they call "slow set " you haven't got time.Comes in clear and opaque, the product I use is not a true white like Alumilite but very close.

UV RESIN

Probably not used a lot by pen turners /casters as as its name suggests it is cured by ultra violet you can take it outside or use a UV lamp, I have used this to stick mirrors back to car windscreens and for repairing Swarovski crystal and other glass with a high lead content.I am not going to say much more as I doubt that many of you will ever use this.

As I child I had access to many wonderful things that health and safety have now banned, my dad ( now deceased ) was involved in the development of a type of epoxy for use in the aircraft industry and also worked on Concorde, so I gained a lot from him. I had my first motorcycle before I was 7 years old and my first car when I was 12, I later became a design engineer like my dad and began to add to my knowledge of adhesives and resins. It is from this back ground that I make the above statements just in case anyone is wondering .

I hope this helps many of you casting or thinking about it

Good Luck :winking::thumbs::thumbs:
 

Grump

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Aug 17, 2013
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Brian
Jim, can you add a casters forum to the board so I can avoid it?
All these dodgy practices and unhealthy goings on is bringing back to many bad memories.
I will not give advise on how to ruin your health and too many of you want to do it.
 

ataylor

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Andy
Thanks for this I dont do any casting as yet but who knows in the future.
 

Tephy

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Steve
The Alumilite I got from Metal Clay recently says it takes 24-48 hours to set :nooidea::thinks:

this is the full cure time . working time of Alumilite is normally about 10 mins max on warm days it is a lot faster. Once set can be worked in about 30 to 45mins
 

paulm

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Thanks Steve, that is very interesting. When starting out, this casting malarky is a bit of a minefield and something like this helps. :thumbs:
 

Tephy

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I just hope I haven't wasted my money buying alumilite as I don't have a pressure pot and I can't really justify buying one so I hope it works.

When mixing go gently and try to create as few bubbles as possible, when pouring into mixing cups don't " glug " it as this causes bubbles and when filling the mould start from a corner and go gently try not to trap any air. If you have the white alumilite you might not see any until you cut or start turning ,if using clear you can always fill with CA. Don't try to drop a perfect one first time and then give up if it fails , treat it as a learning curve. The very first time you used a lathe were you perfect ? Learning is what it is all about, the most important thing is to have fun
 

Tephy

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Steve
Wonder how fast it will set on a warm 40°C day?:thinks:

get the 2 parts in mixing cups get everything ready and to hand then .... mix when it goes clear add dye stir mix pour ...whack it in pressure pot tighten top let pressure in .... breathe
I have stumbled tightening down the top before now and had it go off before getting pressure... it starts to gel you need pressure at that point at the latest once it gels past a certain point you are buggered ( technical term ):tongue:
 

Tephy

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Steve
Just a quick one I forgot to add are you aware that resin has a shelf life after which it is no good? Most resins have a shelf life of around 6 months after that it is in the bin. I have seen some very reputable DIY stores that have silicone and other products on their shelves which are way past their self life, went to buy some Sikaflex from one company that was solid in the tube and about 18 months old, the shop had no idea, thought I was joking so I waited there while he phoned and checked. He was not chuffed at having 3 cases to throw in the bin. Remember 'buy it when you need it' and 'fresh is best'
 
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