Builders Bog cures by a chemical reaction which consumes the volatile component as it cures – tying it up as a cross-linking agent in the chemical reaction. If you add insufficient hardener, this reaction will not go to completion and you will be left with a weak compound that still smells strongly of styrene monomer. We adjust the gel time of every batch to between 6 and 8 minutes art 22 Deg C. using 40 gram of paste and 1 gram of hardener. This is 2.5 % by weight and 1.9% by Volume.

This is the ideal ratio for cure. You can go outside this and still obtain good cure, using from 1.1% to 5% by volume of hardener and this will vary the gel time. But 4 match heads to 250 ml will be about 0.25 ml. to 250 ml or 0.1%, which is far too little hardener. You can extend the gel time by putting the two components in a fridge first. Or use successive smaller fills one on top of the other. But you will not be able, at room temperature, to get longer than about 18 minutes working time before you spoil the cure.

The whole concept of Builders Bog is that it is fast enough for a tradesman to complete a job and finish-paint it in a couple of hours. Whereas water-based or solvent based fillers take longer and longer to dry as the thickness of the fill is increased, Builders Bog does the opposite, so the thicker the fill the more chemical heat is given off and the faster it cures.

I hope this helps
Regards Stuart Jordan
Managing Director