At work I needed a suitable way to check the calibration of gelcoat spray
equipment. Gelcoat requires an initiator (often called “catalyst”) in the form
of a peroxide to cure. The peroxide/gelcoat ratio is important, so it is
checked regularly by spraying the separate components into suitable
containers and weighing them.
For those familiar with gelcoat spraying, this is not a system with coupled
gelcoat and peroxide pumps. But rather an external mixing spray gun where
the peroxide is simply fed from a pressurized container to the spray gun.
Since we’re handling resins, solvents and peroxide, protective equipment
including gloves is a must. That makes it cumbersome to whip out a smartphone
to use it as a calculator to check the ratio. Since you don’t want to get
gelcoat or peroxide on your expensive phone, you have to take off your gloves
to handle it. This would have to be repeated several times.
So I decided to make a diagram where one could relatively easy read off the
peroxide percentage given the quantities of both components. This can be
printed and laminated between plastic to make it resistant against stains.
The whole thing can be found in a github repo.