Permacoll is a water-soluble synthetic size formulated to stay tacky and receptive to gold leaf for an extended period. Unlike traditional casein or fish-based sizes, Permacoll maintains its working properties over hours rather than minutes. This makes it practical for contemporary applications where traditional timing is not always feasible.
The working principle is chemical. Permacoll forms a slightly different surface than traditional size. The adhesion is slightly less aggressive—the gold does not bond as quickly—but the bond is still strong and lasting. The advantage is that you can work more methodically. You can apply gold to larger areas without rushing. You can adjust and reposition leaf if needed.
For studio work, Permacoll requires slightly different technique than traditional size. Burnishing is typically delayed longer—the size must cure somewhat before full burnishing. The moisture dynamics are different. But the final result, when properly executed, is equivalent to traditional water gilding. Permacoll is part of how contemporary gilders maintain the standards of water gilding while working at realistic pace.