Thank you all for support.
I just applied some tannin to get rid of whiteness of fresh wood and than varnish but only as much as soaked into wood and rub off rest. But I can't say if it is good or bad.
Looks to be available here https://sklep.mnp.art.pl/produkt/polska-szkola-lutnicza-2/
I am going to buy one, so if it is not available for you I can order 2 pieces and send one to you together with violin.