FrameItEtc,
You are right. The foil holds up equally well on plastic, glass, stone or wood.
However, a good finish is not about foil holding up well, but about "foil" showing through and looking right, mate or shiny, opaque or transparent at will. A good finish has plenty to do with what's going on beneath the foil. More over, a truly good finish has to do with the transparency of the "foil" too. And only genuine gold (silver) can be rubbed to different degrees of transparency.
Metal leaf (imitation gold) was introduced in the market when some smart businessmen noticed that most people can't say the difference between distinguished, elegant and precious gold finish, and cheap brass foil finish, especially if the latest was very inexpensive and could fool the untrained eye from across the street. Much like plastic molding today, imitation gold opened a profitable and crowded avenue populated by less affluent and demanding people. It's worth mentioning that
1. Imitation gold is notoriously unresponsive to any sophisticate finish approach, for which reason it is always less expensive to go for genuine gold finishes when quality and accuracy is needed than try coping with metal leaf
2. Noticed that those gilded statues and cupolas are NOT finished in metal leaf ("foil finish") even though most by passers can't say the difference between gold and brass foil?
EllenAtHowards,
You put that wide plastic molding of yours at its truly best use. Gilded wood in the open does not last long
as a sig. If you were having a bookstore and wanted a large book for a sign, a large plastic book would still be your best choice for that purpose.