If the sewing cabinets are later models then they could have a lacquer finish on them. I mean after the 1940 or so. They sealed the wood with wood filler to close the grain so the lacquer would be very smooth. Stripping will not get this filler out of the wood grain and tung oil will not penetrate properly. This is one reason I use shellac. They used lacquer because is dried in just a few minutes. Shellac dries to the touch in 30 minutes and can be recoated then so with in about 2 hours you can apply three coats and the next day can be used. You can rub down the finish with paste wax(I use briwax clear) and 0000 steel wool, this will take the new look off the finish.
Billy who need the NB anyway!!! Glenn