I bought mine from local Fish store too. It's a Malaysian Driftwood. I boiled it for a few hours and once the water turned tea colour I poured it out and filled with new tap water then add some aquarium salt to the water while boiling. the water turned orange a few times and after the 4th times boiling I got rid of most tanning colour. And left it in the warm water over night to get any unwanted tanning. It still getting a bit yellowish but after I poured it out again and add warm water then my driftwood stopped leaking tanning
Hope this help you solve your problem too. Mine is happily with tropical plants in the tank right now (Anubias Barteri, java moss, indian fern and soon will be java ferns this weekend).