After shellac has been dissolved in ethanol it is possible to introduce additives that cause the shellac to cross link over a period of about 20 days after application. This can be shortened by 2.5 days for each 10 degree increase in temperature with lights or a heater. This additive has been mixed to be appropriate for maximum hardening. It is added after the shellac has been put in to the solution. Weigh the shellac before putting it in to the solution. Keep some metho aside from you shellac mix so that you can wash all the additive out. Stir it into the shellac solution. The hardened shellac can be used on table tops so that condensation & heat rings do not occur. Also increases resistance to alcohol.
The additive must be in intimate contact with the shellac solution for 72 hours before the hardened shellac can be used. Application gear must not be allowed to go dry otherwise brushes, rubbers & spray nozzles will go rock hard. Wash them out well with metho. For heat resistance on window frames, tables etc, every coat should be with hardened shellac. Process of application & coating time gaps of hardened shellac is identical to unhardened.
Using some oil on long strokes to prevent rearing seems to work for some, yet others report difficulties.
This additive slightly slow drying which reduces blooming & allows for a brush to be used on large surfaces without the ‘edge’ drying and allows
spraying without pock marks.
For lesser weights of shellac, use 10ml to 10g of shellac. Scale up to 50ml for 50g,100ml for 100g, 200ml for 200g etc.