I have a project I would like to attempt but not 100% on how to achieve it, any input would be appreciated.

I am looking to use a white epoxy or polyester to encapsulate some wooden branches to create an indoor table top. I will cut a flat surface onto the branches before laying them into an open mould. The branches will be visible on the table top but as the epoxy/polyester will be pigmented white you won't see any branches that aren't on the top surface. I hope that makes sense.

The upper surface needs to be durable, i.e. not easily scratched and fairly resistant to heat. It also has to be UV resistant - no discolouration.

Initially I was thinking of using Waterclear Polyester Casting Resin with a white pigment and treating the wood with Polyester Infusion Resin before pouring to reduce are bubbles.

My concern with this approach is the durability of the Waterclear Polyester as a table top.

Would it be possible to pour a very thin (1-2mm) layer of epoxy (with white pigment) in order to get the durable surface then make the bulk of the'body' in polyester (up to 50mm thick).

Is this possible?

Would the epoxy yellow over time?

Is there anyway I can use filler in the polyester pour to reduce costs?

Is there anything else I should consider?

TIA

Matt

Easy Composites have some pretty UV resistant epoxies these days, so that probably is an option. I'm sure one of their staff will be along to suggest the ideal product. 

Thanks - good info

I've ordered some small quantities to try a layer of epoxy cured and then polyester. What should I expect to happen if I did this?

I'll try polyester on its own to see how durable a finish I get.

Your biggest concern should be controlling the heat build up from the reaction, especially PE resin - less than 1" of resin in a bucket can catch fire, let alone 2"

I guess keeping volumes low and doing several pours would be advisable.

The reading I've done suggests heat build up but no one has said anything about fire risk. The datasheet for the polyester I've gone for says it's good for up to 75mm which was one of the reasons I selected it.




https://www.easycomposites.co.uk/casting-resins/water-clear-polyester-casting-resin.html

Polyester casting resin is different to polyester laminating resin, you can do thicker pours. In fact I believe polyester casting resin has less exotherm than most epoxy casting resins, it's quite a low exotherm resin. 

Another potential difficulty that you may not have thought of: have you considered how you will 'seal' the wood branches to your tool surface to prevent the resin leaking underneath where you don't want it? Resin will find its way into extremely small gaps, it flows quite a lot like water. So even if you have your branches cut extremely flat so that they appear to sit perfectly against the tool surface, you will probably find that the resin leaks underneath and causes some funny patterns where you don't want it to be. 

Thanks Hanaldo

I'll trial epoxy and polyester separately. I'm not convinced the polyester casting resin will be durable enough for a table top.

The plan is to pour a small amount of resin and place the wood into the thin layer which will hopefully fill all the gaps. I'll sand back the surface if its not perfect. I've also purchased a polyester infusion resin to treat the wood prior to casting.

I was planning on doing this in the garage but it sound like the exothermic reaction of polyester is very temperature sensitive and the garage will be too cold.