A possibility

Capstonecare: stone and wood care products (polish, clean, restore, seal) ... FZ-Protective Impregnation The Lithofin special product for finely finished, ...
www.capstonecare.co.uk/catalog/default.php?cPath=1_4 - 34k

Red alder wood is used in the manufacture of fine furniture, ... Once the problem of protective impregnation was solved, large amounts of Beech were used on ...
www.the-tree.org.uk/TreeCultivation&Uses/Uses/usesofwood.ht...

Clear wood impregnation, containing biologically active ingredients, ... Not a finishing treatment - must be coated with a protective finish such as One ...
www.greenshop.co.uk/acatalog/Wood_Protection.html - 45k

that's what they call it (for wood) in the US. Note that coating is a noun here!

Perhaps I am overtranslating... mi sembra che ci voglia qualcosa di meno generico in questo caso; protective coating puo' riferirsi a tante cose, come ben spiega l'articolo che ti cito in calce ("Understanding Wood Finishes"). Per essere impregnante la mano di sostanza protettiva deve essere a base di olio, che penetra nel legno.

"Oil Finishes
These types of finishes have been used for centuries to treat and preserve wood. Oils are different from most other finishes on the market because they seep into the wood and penetrate the wood’s fibers. Because of this, oil finishes cannot be built up to a thick coat like polyurethane or varnish can. They offer less protection but are also easier to apply which is their primary advantage. Another advantage is that simply simply wiping on more oil can often repair minor scratches.

There are two types of oils, those that cure and those that don’t cure. Oils that don’t cure should generally be avoided because that can continue to seep into the wood leaving the surface unprotected. They can also leave a sticky surface on the wood. Linseed oil and Tung Oil are both oils that cure and work well as finishes."