Casting Burrs

[Chilprufe]

I have a few elm burr offcuts and i'm planning casting then in resin, but i'm not sure will it work with polyester resin, with the shrinkage you get in PR will it delaminate from the wood? or am i better casting it with a polyurethane resin? any help would be much appreciated.

 

[robutacion]

Well, if you have the option of resins to use, I would go for the Alumilite as it has more wood adhesion strength.

I only use PR and I cast all sorts of wood with it, there are 2 things that I found that can assist PR to stick to wood better, one is to soak the blanks in un-hardened resin overnight, then cast as normal.

The other things is to look carefully at the resin/wood joins after you get your blanks resized/sanded and using the thinnest CA you can find, pour some into that same joint until it soaks no more. The very thin CA is capable to go through any gaps or separation between the 2 materials however, don't do this for the first week of casting those blanks, as any shrinkage will happen by then while too soon and the CA does nothing.

The CA that finds its way through the 2 materials, is invisible when turned so, a simple and effective way to solve some of the possible separation issues when using PR with wood...!

Good luck,

Cheers
George

 

[Dai Sensei]

I too only use PR as here in Australia we have limited resin types that are cost effective. Yes it can have "sticking" problems, but I find as long as I ensure they are clean dry and walm (both resin and wood) and using pressure casting it works pretty well.

As George suggests, thin CA can also help or fix any failures. Stabilizing with Cactus Juice after casting will also fill/seal any shrinkage issues.

Cheers

 

[Chilprufe]

I will be using vacuum to make my blanks which should give me a slightly better contact as well ... but as you say the cost of some of the resins are just not cost effective, especially when your experimenting. Also the lack of availability of some some resin brands.

 

[robutacion]

I too only use PR as here in Australia we have limited resin types that are cost effective. Yes it can have "sticking" problems, but I find as long as I ensure they are clean dry and walm (both resin and wood) and using pressure casting it works pretty well.

As George suggests, thin CA can also help or fix any failures. Stabilizing with Cactus Juice after casting will also fill/seal any shrinkage issues.

Cheers

Neil,

I'm yet to try stabilising after casting, a though that did come to to mind, some time back however, I'm a little sceptical on to what cactus juice and PR will do together...!!!

You obviously have tried this with "some" success, I wonder how much and what woods you had embedded in the PR...???

Cheers
George

 

[Dai Sensei]

Neil,

I'm yet to try stabilising after casting, a though that did come to to mind, some time back however, I'm a little sceptical on to what cactus juice and PR will do together...!!!

You obviously have tried this with "some" success, I wonder how much and what woods you had embedded in the PR...???

Cheers
George

Hi George

I've cast a lot of timbers in PR, anything that isn't whole blanks, well known for it on the Aus forums rather than on here. I also do other cast blanks, ie pepper grinders and turning blanks, not just pen blanks.

I don't use Cactus juice on all blanks, just those woods needing stabilizing such as the wormy mango and other spalted woods, plus seed pods and croc jaws. I have had no problems with the Cactus Juice & PR, but always do the stabilizing after casting, as PR can have issues with other resins.

I will be using vacuum to make my blanks which should give me a slightly better contact as well ... but as you say the cost of some of the resins are just not cost effective, especially when your experimenting. Also the lack of availability of some some resin brands.

DON'T use vacuum when casting your timber, especially elm that is relatively porous, use pressure. The vacuum will continue to draw air through the wood before the resin goes off, resulting in your PR full of bubbles, and if cast in normal molds will cause the resin to overflow out.

 

[Jim Burr]

Good advice so far! I have good results pressure casting with PR then stabilizing in the vaccum. YMMV and this is a good time for Curtis to pop in!

 

[BangleGuy]

I have vacuum stabilized alumilite potted wood blanks with Cactus Juice and had good success. The main concern would be the 200 F baking step, which did soften the alumilite slightly but didn't degrade the blanks or cause separation.