Rather than using pumps or measuring in cups, I made a balance to get my resin/hardener mix ratio. There are lots of great ways to get that correct mix ratio and the more exact you can get it the better off you'll be in the end. This way worked well for me, and there was no burping the pumps, no counting, no trying to eyeball the line when filling the container to a mark, and you measure and mix in the same cup which gets thrown away after use (it is easier and cheaper than tyring to clean and re-use 'em). It works for any batch size you want(limited by the size of cups I used). (I do however use the small pharmaceutical dosing syringes / condiment bottles technique for micro-batches.)

The RAKA 127/350 I used has a mix ratio by weight of 43:100 -- I made the dimensions of the balance accordingly. I pour in the hardener first, balance the scale with the counterweights, then move the cup to the outer hanger, and pour in the resin to get the scale to balance again. It is simple to use and you're certain to get an accurate mix every time. (The design also allow for the possibility of overshooting on the resin pour with a way to re-balance and add correct amount of hardener -- but, on the whole kayak project I only had to correct one overshot pour). (And, I did pour the resin and hardener into smaller containers for use as the gallon jugs are a little clumsy to pour from.)

-John D.