BL is only about 10% impervious . This is why with original stocks you often see them darken greatly . This is called a patina and its caused by dirt , oils from you hand and moisture getting into the oil . While the oil does feel dry to the touch , its infact not completely dry , ever . Its also why when we do a repair , we can often match the color . As the oil is only about 10% impervious , you can stain through it .
However harder more deeply penetrating oils like Tung , are around 90% impervious . IE they do not allow a great % of penetration. Be that from other oils like from your skin , or moisture . . Also because they penetrate so deep , its very difficult to do a repair and match the original color of the stock . So you either have to float the color of air brush it . Then re oil over it . Your only other option is to sand the wood to a level below what the penetration level of the oil . In doing so you have to be very consistent in your depth or you get blotch stain patterns.
The other thing with sealer s is that the stock must be able to breath if it doesn’t and you miss an area , over time you can end up with oil rot .
2nd is the consideration of what you want in your finish . There are basically two different types .
You have whats called an American finish or a European finish .
The American finish didn’t really become all that popular tell the mid 20th century and is what you often see on higher end guns today . Its very smooth and is done so as the pours of the wood are all filled and level like glass .
Prior to that you have the European type finish . With that finish the pours are left visible and un filled . This doesn’t mean they don’t have oil in them . It just means that the grain and pours show
The nice thing however is that oils like tung have a larger molecular structure then oils like Linseed . There for the linseed will hold the harder Tung oil above the wood while at the same time bonding with it so that you don’t get separation/ flaking which can happen with lacquer type finishes when moisture gets under them .
There is frankly no need to put on countless layers of Boiled linseed . You can just put on one very good flood coat . let it set for 15-20 minutes then wipe down the excess.
Once dry apply a 2nd light coat and rub it in , nice and smooth . After that add a couple even lighter coats of Tung . .
If you work slowly in your rub down coats , there is nothing IMO that will produce the depth , color and translucency of oil
