I would stay away from store purchased, I used some from awhat you could get at a store and this was not treated with any chemicals, how do I know cause I spoke to the representative of the company which supplies our company which happens to be one of the biggest Lumber suppliers in the North East. He said with the way they go through this lumber they dont even have time to treat it but other smaller companies will and do. I would use your firewood and make sure if your gonna put it in your carboy that you make it small enough to allow for some expansion of the wood as my toasted sticks barely made it out of a one gallon bottle. Judging by the smell and taste of the wood that came with my RJ Spagnols kit, it doesnt even come close to comparing with the quality, I will throw mine away and just buy some. I must say hat my wine came out okay with it and the house never smelled better then when toasting that but I dont think it compares to the chips at the store and definitely not the Stavin cubes.