Epoxy ratio verification method

[jbo_c]

Good list so far of ideas that might work for new folks.

(How did I never think to use Tom’s cheapo measuring cups idea?)

Jbo

[joe2700]

To throw one more opinion in the mix, I'm a fan of mixing by weight on a small digital scale for all epoxy products. I used to measure liquid epoxy in paint mixing cups but no longer trust them without verifying after a batch that was mismarked and very wrong. All the system three products give the ratio by weight right on the container. I mix by weight in grams and then visually confirm it looks about 50:50 by volume as a backup. You can clearly see the line between resin and hardener in the same cup if you haven't mixed yet. Additionally it's easier for me to look down and read the scale from above then get to eye level with the mixing cup while pouring.

When mixing paint or products that don't specify a ratio by weight I check the mixing cup markings are accurate by weighing water then use the markings on the cup.

Doing it all by weight has been the most repeatable way to mix accurately without mistakes for me and doesn't take me any longer.

[OneWayTraffic]

You can mix by weight even when a ratio is specified by volume.

Measure 100ml of hardener and weigh. Call this A.

Then measure 400ml (for a 4:1) of resin and weigh. Call this B.

Then divide A into B to get a ratio in weight. For my 4:1 generic resin I got 4.5:1. I always add one to get 5.5:1 which is the total weight of resin+hardener: hardener.
Then measure any amount of hardener first. Multiply by 5.5 and then pour resin into the same cup until it reaches that number.

e.g., 15g hardener 15*5.5=82.5g.

Pour resin in until it reaches 82.5g.

Important to add the hardener first. That way any slight pouring mistakes will be with the resin, and less critical to the overall ratio. If I screw it up, and go say 10g over I then just add a couple grams hardener.

Doing it this way, I have never had a batch fail to cure.