Can someone explain the different resins please

[dr4g0nfly]

I've never tried casting resin but from everything I've read about it the stuff used is Polyester Resin, a 2 part plastic.

Then I come across AuS MaDDoG's thread 'Taking The Next Step (Casting)' and he's using West System's Epoxy Resin.

I think of this as a thin marine 'Araldite' type of glue. Which I use it for waterproofing the inside of vases and giving a great smooth shiny finish where I can't get the abrasive.

Can it be used for casting, I'd have thought it would be too brittle to turn once set.

Please somebody - sort out my confusion and teach this pomme, MaDDoG's tricks!

Thanks,

[Bernt]

I was explained in a fiber glass shop: fiber glass resin shrinks more then epoxy resin. Epoxy resin yellows more then fiber glass resin.

For filling gum veins or pockets in timber I use epoxy because it doesn't shrink as much and the yellowness is not very noticeable. For casting I suppose the polyester resin would be more suitable if you want the color to last.

If you go to a fiber glass supplies shop you probably find all you need and the professional advise to go with it.

[benupton]

You can use clear casting resin
Clear Casting Resin : Adelaide Moulding & Casting Supplies (http://www.amcsupplies.com.au/index.php?main_page=index&cPath=398_400)

[dai sensei]

There are lots of different resins with lots of different uses and associated costs.

For casting the cheapest is fibreglass resin (resin plus catalyst), but it is not clear, so only good for solid tinted work. It also goes yellow in time and can only be cast in relatively thin layers.

Next is clear casting PR (polyester resin - resin plus catalyst), this is by far the most commonly used by back-yard casters. Good for most things except it doesn't stick that well, so for WW applications you need to cast under pressure, but even then some thin CA may be necessary.

Then clear casting epoxy (2 part resin), often 3x PR cost, but does stick well. It should only be cast in relatively thin layers. It does not pollish as well as PR.

Then Alumilite (2 part resin, and there are various types), fast setting clear product a lot in USA use, but not available at a reasonable cost here in Aus (ie 4x PR cost) unless you want to ship in a 24gal drum.

Hope this helps.

Cheers

[dr4g0nfly]

Thanks for taking the time to set this straight for me guys.

I'd never considered using fibreglass resins and never heard of Alumilite before.

As always the group mind is more knowledgeable than the individual and to quote dai sensei 'Every day presents an opportunity to learn something new', and with any luck that will be the first of several for today,

thanks,

[dj_pnevans]

If you sand your WW resin will stick to it real good.
David

[NewLondon88]

If you sand your WW resin will stick to it real good.
David

if you use a bit of cobalt napthenate and styrene thinner to mix
with a bit of resin, you can make yourself a primer. It will
seep into the wood and never let go, so the resin will form a strong
bond to itself. Some say to mix the cobalt with acetone 1:4 and
paint that on the wood for a good bond, but I've never tried that.

ps. never let the cobalt come into direct contact with the catalyst alone,
as it will explode. or at the very least, go up in a puff and leave you
with a room full of noxious cloud.

[dai sensei]

if you use a bit of cobalt napthenate and styrene thinner to mix with a bit of resin, you can make yourself a primer. It will seep into the wood and never let go, so the resin will form a strong bond to itself. Some say to mix the cobalt with acetone 1:4 and paint that on the wood for a good bond, but I've never tried that.

ps. never let the cobalt come into direct contact with the catalyst alone, as it will explode. or at the very least, go up in a puff and leave you with a room full of noxious cloud.

Thanks, I'll have to give it a try, just need to find out where to get the cobalt napthenate here :?

[NewLondon88]

Thanks, I'll have to give it a try, just need to find out where to get the cobalt napthenate here :?

It is used to 'pre-promote' the resins, so it is possible your supplier would
have it. Or the manufacturer could probably tell/sell you some.