My Oil in Pad-can - Risk of Contamination?

To reduce friction on saws and planes I use a tomato or bean can stuffed with a rag and impregnated with 3-1 oil to lubricate the contact areas of my tools. I have used this for 50 years with no problems but woodworkers raise this question from time to time. Here is an original blog post:

Question:

Mr.  Sellers :  

I stumbled upon your you tube channel a few weeks ago, have watched most of your videos and am very much inspired by them. 

I've been curious as to what oil is in the can that you use to lubricate your planes and saws.  In one of your son's sharpening videos which I watched earlier this week, he mentioned that it is 3-in-1 oil.  I've no doubt seeing the care with which you undertake matters that you have determined that this oil does not contaminate your finishes. Do you have to do anything to assure that this is the case? 

Paul

Answer:

The oil on the rag in the way shown in the blog post will not affect finishes in general, but this another good question. In general, not all finishes are affected by oil unless the oil is excessive or some has penetrated the surface and prevents the finish from adhering to the wood. Many oil finishes will be unaffected except that machine oil or the like will perhaps have changed the colour in a localised area and thereby show as a blotch when the final appearance is done. I think most people are more concerned that they have read of problems occurring by silicone which causes 'fisheye' in the finish. Silicone is in most furniture polishes and such and so when refinishing, if silicone is on the surface before applying finish, even a small amount, the surface tension of the finish is broken in that area and causes the 'eye' or 'eyes' to appear in the surface. Not pretty and very undesirable. In 50 years of using the 3-1 oil I have never know any problem with finishes. That said, I also know that the impartation of oil to the plane is so minimal you can scarcely get it to colour your fingertips. Only when the oil is put into the rag is the amount more than needed. When the pad-can stands on the bench for a short while the oil is dissipated into the rag more evenly. Once you use this tool you will never want to be without it.