Does anyone have any hints & tips on making really nice-looking cubes out of polyester clear casting compound - mould materials, polishing methods etc. I've not found much beyond some very basic guidelines so far - hints from people who've actually done it would save a lot of time & experimentation....
of polyester clear
people who've actually
You can get some lovely shapes from Ice Maker Trays. It is a simple process, as long as you follow the instructions on the packet. Food colourants make great dye for different layers. Remember to cover / reseal the packet as soon as you have dispensed your powder, as moisture can ruin it if left open. A tupperware tub is good for storage.
Glass and smooth moulded plastic containers make good moulds. Finger prints stay on the material if you touch it while it's still curing, so give it its full setting time. But, as I've said already, follow the instructions on the packet and you'll not go wrong.
Have fun.
Powder? I've only ever come across 2-part liquid resins. Any preference for either type?
If you're using either, then go for it. I have tried both, but the powder was my personal preference. There are two types of powder resin. One is dissolved in plain clear water, which takes ages to cure but is good for moulds with organic things in, like flowers and insect displays. And the other type with a solvent, which is good for quicker curing and with inorganic items in the mould. But either makes a nice moulding.
I got in to the process when the oldest daughter wanted to try it after her experiments at school with it. We get most of the supplies from a seller on eBay. The shops around here are expensive for this type of stuff, so eBay was the cheapest we found. Now we have ornaments made from photographs and items we've got on holidays and things. The colouring of layers as a background or base for the moulding, is great fun to experiment with.
I have a long triangular name sign for my office desk, with plastic gold coloured birthday cake lettering through it. The daughter made it for me about 10 years ago and it looks like it's just been made yesterday. It's got the company colours (royal blue and maroon) for the base and the background and changes all colours depending on the angle you are looking from.
It's great fun. You'll enjoy it when you get passed your first panic. :-)
polyester clear
people who've actually
Used to dabble with it many years ago (anyone remember "plasticraft" as it was called?). That used plastic and glazed ceramic moulds. IIRC it worked much better with a release agent on the mould before pouring. I used two part resin and hardener. It pays to not mix it to vigorously since you don't want air entrained in the mix. With complicated mould shapes a cocktale stick / toothpick is handy to make sure you have pushed the resin into every corner. Once turned out of the mould, you will normally need to sand down the top surface to remove the slight radius caused by the meniscus at the edges, and also take off any finger prints you got on it removing it!
neither sounds like what I have used, which was simply clear polyester resin with a catalyst.
Provided you don't over catalyse it, and make it explode from exothermic heat, it is totally inert for all stuff you put in.
Sounds like your stuff may actually be an acrylic type resin, rather than polyester.
out of =A0polyester clear
When I did this as a kid, I hated polishing. Now I do it, I've got a random orbit sander and then micromesh abrasives (yes, I know they're expensive) to do the rough quickly then put a shine on it. Piece of cake...
Moulds should be as good as you can make them - saves a lot of effort later. Accurate shapes (and lack of deliberate draw) mean less roughing to shape, but releasing without draw needs a flexible mould. I'd be inclined to go for something dismantlable instead, using mylar (polyester) stuck to MDF. A little flash on the edges is fine - it'll fettle off in moments.
It's worth vacuum degassing when casting as it shifts bubbles out of the corners with no fuss - especially if you're embedding stuff. I have an electric vacuum pump, but you can easily de-gas resin mixes or small items with just a Vac-u-vin storage jar (drops to abbout 1/4 atm. which is plenty). Polyester is quite low viscosity so if you're gentle when mixing it you shouldn't have entrained air in the unpoured resin anyway. However for opaque resins or polyurethanes it's worth vac degassing the mixed resin even before you pour it.
Real wholesale suppliers are so much cheaper.
I'd like to see you achieve that with a clear casting resin! (Layup resins, now you're talking)
A'dunno. :-) I think it is acrylic resin in powder form. The polyester resin is the one that gets hot in the mould, so then it must be acrylic powder because it doesn't get as hot as the pouring resin. It goes pasty greyish when mixed with the water, then you add the catalyst powder before you pour it and it cures clear like glass. Is that acrylic? It only says Casting Resin (Clear) on the front of the bag and has instructions on the back.
I thought they were all the same sort of stuff.
out of =A0polyester clear
people who've actually
We don't know how big and what for, but it may be a lot easier to cut cubes from acrylic perfectly cast by professionals (perspex). You can buy precut pieces from many glass or plastic shops, sand and buff.
Leo
Well what you describe i have never come across, so all bets are off.
I haven't a clue what it is!
Sounds like my info is too out of date to be useful, so I'll shut up ;-)
Any more info/leads on powder based resins?
Never come across them and googling on embedding resins leads me to ones do know.
Polyester clear resin , sets really clear , hardens with drops of hardnener, hits gel stage in about 30 mins dosn`t hit hard for another
23 hours, outside stays sticky untill you bake it off.Epoxys step up in cost but lose long hardening time and stay sticky problem.
Always found
Thanks Adam
What sort of time/temperature for baking off?
Any hints for mould release and/or polishing?
Heres a better tip, baking does work but only if have an oven that is never to be used for food:
The casting may remain sticky on the surface even though the underlying resin is fully cured. This is entirely normal and is caused because the clear polyester resin is unwaxed. Wax is added to polyester laminating resin to exclude air and thus cure surface tack free. If wax were to be added to the clear resin it would not remain clear when cured.
This surface tackiness may be overcome by covering the exposed top surface with a piece of cellophane while the resin cures. The same result may be obtained by spraying the tacky surface with PVA release agent. PVA release may be washed off with water prior to sanding and polishing. This surface tackiness may also be removed by wet sanding with wet and dry abrasive paper (W&D).
Polyesters release from slicone and polyethelene moulds without release, latex inhibits surface cure apparently.PVA or wax polish wrok as long as careful to coat everything. Better the mould surface less polishing required after, usual 100- 1200 w7D treatment.
The Prop Builder's Moulding and Casting Handbook by Thurston James is an excellent book on general techniques.
and the very active Casting mailing list
It's used by dental technicians in making false teeth. It's cast into the shape of the plate that the teeth are moulded in. Acrylic Powder and the catalyst is a polymer of some kind. Non-Toxic, which is probably why it's used in making false teeth, and is simply mixed with water. And, I've just been told, it's also used by manicurists to sculpt finger nails.
All I know is, we used to get from someone on eBay, but the daughter now buys it in 1Kg bags from a shop in town. When she gets home, if she comes home tonight, I'll try to find out more about it.
Alginate is the mould making material, made from seaweed used to have a plant near Girvan, it dosen`t get hot while curing and dosn`t immediately shrink a lot makes it good for life casting , unlike plaster which gets darn hot in bulk.
Thanks to BW now know acrylic powder is methacrylate family of resins and used for denture making and acrylic nails and for Lucite (R) embedded trophys, still can`t get a handle on a good price though.
Thanks Adam
Bondaglass Voss, Beckenham, Kent are specialist suppliers of this type of stuff. Alas thy don't have a website
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