epoxy joint

[Adam Glatt]

West Systems also offers hand pumps for the resin and hardener cans that 
pump out the proper ratios. The downside being that you can only mix 
integer multiples of the "one pump" amount, which is more than needed 
for small jobs.

Keith Black wrote:

> Brian, I look forward to Gray's answer, but I can share my experience 
> with West Systems epoxy.
>  
> West Systems epoxy is not a 1:1 mixture like many of the hobby 
> epoxies. As I understand it the 1:1 epoxies have extra fillers added 
> to the hardeners to provide the 1:1 ratio to allow for easier to 
> mixing. West Systems uses five parts resin to one part hardener. When 
> I first started using the West epoxy I tried measuring the volume 
> either in a small mixing cup or sometimes counting drops (when using 
> very small amounts). This yielded very unreliable results, sometimes 
> it hardened, sometimes I just made rubber. Then I broke down and 
> bought a triple beam balance that measures to the 10th of a gram so I 
> can mix by weight. Using this method I'm able to mix very small 
> quantities and it always hardens properly.
>  
> My "guess" is that the hobby epoxies add fillers such that the volume 
> of the hardener is equal to the volume of the resin.
>  
> BTW, for those using the epoxies from the hobby shop, I highly 
> recommend trying the West Systems epoxy. This stuff is MUCH cheaper by 
> volume and seems to be a much higher quality epoxy. You purchase one 
> resin and different hardeners for different drying times. Also, they 
> have a larger variety of fillers for various purposes, I personally 
> like the Colloidal Silica (406) which will thicken up the epoxy to 
> keep it from running, but unlike micro balloons it is extremely 
> strong. (This is not my own discovery, Lance Van Nostrand sold me on 
> the West Systems epoxy, thanks Lance!)
>  
> Keith Black


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