: I see one problem with this, at least for me. It is easy to overshoot when
: pouring resin or hardner. ... On the other hand, the same
: can be said for Pete's scale method.

Thanks for the nice compliment, Al.

I'd like to offer a clarification of 'my' method.

While you may find this difficult to believe, I do sometimes overshoot with the hardener, but the correction is pretty straightforward:

The digital scale has a built-in tare function, so I turn the unit on with the empty cup already in place. So, any readings on the display are of the epoxy mix only. That makes it a little easier.

Let's assume I was able to get 100.0 grams of resin into the cup. That's what the SCALE display will read. I multiply that by the appropriate constant for hardener. Let's say 1.44. The CALCULATOR display now reads "144.0". Then, watching the readout on the SCALE, I add enough hardener to reach that number. That gives me my correct batch.

But, like you said, sometimes too much hardener gets in there. Smoke gets in my eye at the critical moment, I don't modulate my squeeze on the bottle properly, or I'm just not on the ball that day. Or night.

So, let's say that instead of ending right on the money at 144.0, I instead find that the SCALE display now says 154.0 grams, or 10 over. All is not lost.

We know I have 10 grams of 'extra' hardener in there. Multiply that by the inverse of 0.44, or 2.2727, (or simply divide by 0.44) to get the amount of additional RESIN needed to bring the mixture back to optimal. In this case, then, I would add another 22.7 grams of RESIN.

Yes, I'd end up with a batch of 176.7 grams of epoxy mix instead of the targeted 144, but it would be of the proper ratio. Sometimes I can successfully freeze the excess until I need it.

By the way, even shopping around on the web, I 'had' to spend more like $100 to get the capacity and sensitivity I wanted: 500 grams in 0.1 gram increments. That's a bit much for someone assembling a single boat, but I'm sure they will get cheaper, just like most electronics. That little $2 calculator I had at the demo gave up the ghost sitting there in the sunlight, so now it's a BB-gun target hanging from a tree branch in my back yard. I remember when the first HP pocket calculators came out, the ones with the red LED displays. Introduced in the mid-70s, they were about $100 for the same capacity as that $2 job.

Pete,
in Snohomish, Washington