After reading (with considerable interest) the thread on DIY defoamers, I'm left wondering if the rinsing aid liquid intended for dishwashers might be used to prevent excessive foaming in grain-based washes during distillation. We make and supply products for home and craft distillers, and especially our home distilling customers have apparently been experimenting with a variety of grains lately, some of which may be somewhat high in protein and other compounds promoting wort viscosity, and we've had a lot of inquiries about products to prevent "puking". The only commercial product on the market in our neck of the woods is a silicone-based defoaming agent which works well but is expensive and difficult to obtain. The combination of 1/2 tsp of olive oil and 1 drop of dishwashing liquid per liter of wash (as suggested in the above thread) works, but on a 5 gallon batch of wash you'd need quite a bit, which makes some of our customers worry about residual flavors.
The "rinse aid" liquid used in dishwashers, as I understand it, reduces the surface tension of water. Rather, it contains surfactants and uses Mangoni stress to prevent droplet formation (Wikipedia) and the latter is based on surface tension while surfactants also reduce surface tension. Rinse aid is also notorious for ruining the head of foam on a beer served in glasses cleaned in dishwashers with rinse aid.
Has anyone tried this? If so, what sort of dosage would be effective? If not, I will conduct my own experiments and publish the results here, but I hate duplication of effort so I'd rather ask first.