Glycerin For Films With Oxalic Acid
The preparation recipe is 100ml water + 130ml glycerin + 120 grams oxalic acid. First the water is mixed with the glycerin and then the oxalate is added. Since complete dissolution is also the most critical factor, the solution should be placed in a transparent container (eg a glass bottle) so that it is easy to check if any sediment remains. The vessel is then placed in a bain-marie and heated (70°C) for 45' with regular stirring until no undissolved oxalic acid remains and the final solution is completely clear. Sponge towels (Wettex) measuring 45 cm x 3 cm x 1.5 mm are immersed in this solution. The immersion is done immediately as at room temperature the solution tends to crystallize very quickly. As much solution is left over, it can be kept in a closed container which will be completely crystallized in half an hour. The quantities described (100 ml water + 130 ml glycerin + 120 grams oxalic acid) create a solution weighing 360±10 grams and volume 300±10ml. Given that the strips as described absorb an average of 27.5 grams of solution each, this solution is sufficient to soak 13 strips. For the application, 4 strips are required per ten bees which are placed in the combs 2,4,6 and 8.