There seems to exist two different procedures to finish wood with vegetal penetrating oils (raw linseed oil, boiled linseed oil, or pure tung oil). One method consists in letting the oil penetrate into the wood passively using only the power of passing time and a clean cloth, referred to as "oil finishing", and the other consists in rubbing/burnishing the oil into the piece ad nauseam, referred to as "oil polishing".
I can't find much information on oil polishing in newer/popular texts -- it seems to be more of a historical method. I may not have the nomenclature completely right, as I can't find a new or old text that covers both methods.
Are these two approaches complementary, or should they be perceived as alternatives to one another? What does the extra labour buy you?
A. Oil finishing
This is coat-wait-wipe dry-and-repeat approach:
- cover the work in a generous layer of oil using a soft cloth
- wait some amount of time between 10-30m for oil to penetrate
- wipe all excess oil with a clean cloth
- wait between 24h and 48h depending on environment
- repeat (optionally de-nibbing with fine sandpaper or steel wool between coats)
Quoting the label at the back of my bottle of BrandX linseed oil:
Apply on well sanded wood, concrete or stone that is free of lint, wax or debris. Apply sparingly with a soft cloth or brush. Do NOT apply with a sponge. For more even penetration, dilute with equal parts of BrandX turpentine or BrandX paint thinner. Always wipe off any oil that has not penetrated the surface after half an hour. Wait until the first coat is dry before applying a second coat...
Similar instructions are given for pure tung oil:
... The first coat should be a liberal one, and you can rub it over the wood with your hand, a soft rag, or #000 steel wool (#0000 deteriorates badly). Allow this application to sit for 5 to 10 minutes so the oil can soak in, then remove any excess with a clean, soft rag or steel wool. Check after about a half-hour for any seeping, and rub this off as well. Let dry completely (24 to 48 hours) between coats. For woods with very open pores, allow an extra 24 hours drying time.
Source: LeeValley tung oil PDF
This approach also seems to be in line with popular practice (at least of the few who choose oil as a finish). E.g., it is what some spoonmakers recommend.
B. Oil Polishing
Some texts describe a much more laborious process, described as Oil Polishing or Oil-Polishing. It would appear that rubbing (and burnishing) is done with a padded heavy object (like a brick), and continues until the oil has completely penetrated into the wood.
Central to oil polishing is linseed oil, and it should be used in its raw form [...] The oil is heated by placing it in a container and standing it in a bowl of hot water which can be frequently renewed. Warm oil will flow much more easily. Assuming that the wood is smooth and clean, a generous film of oil is applied, using a broad brush. The rubbing is done with a soft felt wrapped round a brick, and working from area to area. The first coat will rapidly soak into the wood. [...]
The end of each phase is marked by the disappearance of the oil. The first coat will not provide a mere hint of polish, but if the operation is repeated some results can be expected.
Depending on the condition of the wood the results will definitely appear after the fourth coat, and it will be marked by sweat points as saturation point is reached. These sweat marks should be removed with a rag soaked in methylated spirit, the use of which will not impair the final finish because it rapidly evaporates.
Chap 9, The complete manual of wood finishing, 1st edition, Frederick Oughton, ISBN 0-8128-2890-9, 1983
I can find a similar process described in Staining and Polishing - Including Varnishing & Other Methods of Finishing Wood, with Appendix of Recipes by JCS Brough
Oil-polishing is most useful for table tops, bar tables, counters and spirit cabinets. A dining-room table with an oil-polished top, and the sides and legs French polished, will make a most satisfactory job. [...]
For a table-top or other surface which is large and level, rub some of the oil well into it, and then polish with a rubber made by rubbing a quantity of felt or flannel round a brick or other suitable block. [...] In applying the oil, do not saturate or flood it, but scrub it in, and afterwards rub long and hard. Of course the wood will absorb the oil, even after several applications. It will need much patience to bring it up to a good glow; in fact it might be said that the work is never finished.