Ready Steady Eddy

[Clive S]

I think you should be careful re the temperature read the link to the wests system and it shows that it must not be cold, also I would check with your supply what the shrinkage and compression strength is of their product as there is not a lot of info on their data sheet. Don't forget to seal the inside of the trough because if you have any leaks it won't leave a level surface. Good luck. ..Clive

[EddyCurrent]

It's just that the West data sheet says this;

Minimum recommended temperature 70°F (21°C)
*Epoxy cures faster at higher temperatures and in thicker applications

and the Syntac data sheet quotes the viscosity at 25 deg.C

[EddyCurrent]

Well I'll be having the wood burner going anyway, it says the pot life is about 40 minutes so surely that's enough for it to settle ?

For making the trough I was thinking about using this, do you think the epoxy will eat into it ?

10x10mm, 1.75M, Foam Sealing Tape Adhesive Strip, Draught Excluder, EPDM Rubber | eBay

Edit: this is better, I'd missed the fact that previous stuff was only 1.75m long.
http://www.toolstation.com/shop/Iron.../sd2802/p70101

[Clive S]

Well I'll be having the wood burner going anyway, it says the pot life is about 40 minutes so surely that's enough for it to settle ?

For making the trough I was thinking about using this, do you think the epoxy will eat into it ?

10x10mm, 1.75M, Foam Sealing Tape Adhesive Strip, Draught Excluder, EPDM Rubber | eBay

Are you going to make a moat between the two rails so that they will be both at the same level, also the epoxy will rise up at the edges so make sure you have a wide enough flat plane to mount the rails on say at least 10mm each side. ..Clive

[EddyCurrent]

Are you going to make a moat between the two rails so that they will be both at the same level, also the epoxy will rise up at the edges so make sure you have a wide enough flat plane to mount the rails on say at least 10mm each side. ..Clive

Yes, maybe one each end, I will leave 10mm each side.

[njhussey]

Are you going to make a moat between the two rails so that they will be both at the same level, also the epoxy will rise up at the edges so make sure you have a wide enough flat plane to mount the rails on say at least 10mm each side. ..Clive

Clive, would you say it was easier to drill and tap all the holes for the rails after doing the epoxy?

[Clive S]

Clive, would you say it was easier to drill and tap all the holes for the rails after doing the epoxy?

I take it that you have seen the pics that I posted. When the mdf sides were taken away you will find that the epoxy has crept up the sides a little. I then used a flat file to scrape the high sides away just until you see it marking the centre. I left mine to cure for about 3 days before removing the mdf. I just drilled through the epoxy and steel and then threaded in the normal way. It was way easier than I had thought.

When mixing the epoxy I did it by weight, I was told by the very helpful people at Wests to mix it in a wide container as that would produce the least heat. There is no problem with mixing it in one or two batches, I also used a hot air gun to flash the surface after it was poured to get rid of any bubbles in the surface. I believe that the proportions of the two part mix should be done accurately . Hope all this helps biggest tip is sealing the moat for leaks before you start as that will give you problems. ..Clive

[george uk]

hi

The mixture will certainly start of with a lower viscosity if it's warmer but it will also set faster as well (a rule of thumb from chemistry is a reaction will go twice as fast for every 10 deg C warmer)

I havent read the manuals on these yet, but

i suspect that this would be an exothermic reaction, ( , or endothermic ). If so, it might not react properly outside the recommended temp, and the suggested temp, may be the temp that it hardens the best at.
The rule of thumb mentioned above in the quote, would generally only apply to a stable compound, not a 2 part mix, especialy if that mix is exo or endo thermic

[Wobblycogs]

I would put money on the reaction being exothermic. The epoxide ring is high strained configuration and and therefore would be expected to release a significant amount of energy upon opening. The other reactant is generally an amine and hydrogen can be made to fall off them quite easily normally (fall off being used in the technical sense here ;-) ).

From a chemistry point of view temperature generally only affects the speed of the reaction (within reason, you obviously get different products if the reaction catches fire). There are reactions where the end products you get are dependent on the temperature of the reaction but they aren't very common and I don't think that would be the case here as this chemistry is "aggressive". My guess is that this is more of a mechanical issue. To produce a strong end product the amine hardner needs to be able to cross link the epoxy. If the mixture is cold the molecules won't be very mobile so it's less likely the amine will bump into and be able to link to more than one epoxy leading to a product that is mechanically quite weak. The lower the temperature the worse this would be.

[EddyCurrent]

I realise there will be some heat generated by the mix but do you think the draught excluded can retain it ?