I want to try oiling some of the wooden furniture we've just had made instead of putting on all sorts of chemical finishes. But we've had no luck finding tung oil in Nong Khai. Does anyone know where it can be sourced (in reasonably small quantities) in Udon? We had no luck at Homepro in Bangkok and they couldn't see any such product in stock at all, even in Udon.

You could try contacting True Value and see if they will ship, that is the only place I have seen tung oil so far. http://www.truevalue.co.th

I use teak oil on the furniture I make for home which I get from HomePro (in Bangkok), unless you really want tung oil it is worth looking for.

I also use teak oil for finishing furniture. Both Teak and Tung Oils are made/sold under TOA labels. They were both available in the Mai Sois off the KrungThep-Nonthaburi Road. I have only seen teak oil stocked around here, but you should be able to order either via a decent sized TOA outlet.