Lots of professional beekeepers are using plastic foundation instead of wax foundation. Because plastic foundation is stronger and less likely to break during honey extraction. Bees will generally only draw or build comb on pre-waxed plastic foundation when there is a honey flow on or if they are being fed sugar. This is because bees prefer to build comb on natural beeswax and will only draw comb on plastic as a last resort.
You can melt the bee wax in a skillet and apply the wax on plastic foundation using a paint roller.
Another way is to boil the wax and water in a deep stainless steel bucket. Then quickly insert the plastic foundation into the liquid and quickly withdraw. In this way, the surface of the plastic foundation will be coated with a layer of beeswax
We designed a spray machine to coating the plastic foundation. You can buy the already waxed plastic foundation from us. https://ktbeekeeping.com.au/product/waxed-plastic-foundation-sheet/