Paraffin Oil vs. Mineral Oil

[Ed_McDonnell]

I had been using food grade mineral oil for wet sanding. I ran out of mineral oil and bought some Behlen industrial / commercial paraffin oil at woodcraft to use for wet sanding instead. I had always thought paraffin oil was pretty much the same thing as mineral oil so I didn't read the warnings on the can in the store.

I was surprised when I started using it to find lots of health warnings and ingredients like toluene, napthalene and makusikalene. Not the kind of stuff I want all over my bare hands while I'm sanding.

I've done some research online and have become completely confused. Apparently the name "paraffin oil" means lots of different things to different people and is used interchangeably with either mineral oil or kerosene depending on the forum and country.

What I really want to know is "Is there any advantage to using Behlen industrial / commercial paraffin oil instead of food grade mineral oil as a lubricant for wet sanding".

If there isn't, I'm going to chuck it and go buy a bottle of mineral oil at the drugstore.

Ed

 

[MichaelMouse]

USP (Pharmaceutical grade - it's medicine) mineral oil comes in two viscosities around here. The lighter stuff makes better lube for rubbing out with loose abrasives. Presume the lighter fractions mentioned on the label would also thin the paraffin oil. Would help the sanding because it wouldn't build up thick mush to skid the paper as quickly, same as with rubbing. If that's what you want, rest assured that none of those lighter fractions are going to stay around long. Not that I'd sand in a closet with toluene, personally.

 

[KurtB]

Paraffin Oil

Ed,
My experience with paraffing oil is limited to recommendations by the Behlens rottenstone and pumice applications when polishing polyurethane. It is supposed to be the lubricant of choice in those applications. I've had a fair amount of experience with Toluene, though, and IMO, if you can't smell any of it while you are working with it, the exposure must be pretty small. Would appreciate any updates you discover.
KurtB

 

[Jake Debski]

I used to use "Crude oil" to rub -out years ago. When I couldn't get it any more I was told at that time paraffin oil was basically the same, maybe, I didn't like it, and switched to mineral oil.

 

[Bill Boehme]

Whatever differences that may exist between mineral oil and various formulations of paraffin oil (paraffins are a broad class of hydrocarbons known as alkanes, the simplest of which is methane and can have essentially any molecular weight), the thing that I see as a serious problem with using any of them in any kind of wood treatment is that they will never dry and that would be a problem for any type of catalyzing oil or film finish that you might want to apply over it. Although mineral oil and paraffin oil enjoy popularity as a treatment for treenware, my opinion is that it is a bad idea. The supposed rationale for use on treenware is that they are inert. However, being inert is only one small consideration -- something that never dries will forever be accumulating contamination from everything that comes in contact with it -- that will also lead to the surface appearance gradually dulling over the course of years.

 

[Jake Debski]

Whatever differences that may exist between mineral oil and various formulations of paraffin oil (paraffins are a broad class of hydrocarbons known as alkanes, the simplest of which is methane and can have essentially any molecular weight), the thing that I see as a serious problem with using any of them in any kind of wood treatment is that they will never dry and that would be a problem for any type of catalyzing oil or film finish that you might want to apply over it. Although mineral oil and paraffin oil enjoy popularity as a treatment for treenware, my opinion is that it is a bad idea. The supposed rationale for use on treenware is that they are inert. However, being inert is only one small consideration -- something that never dries will forever be accumulating contamination from everything that comes in contact with it -- that will also lead to the surface appearance gradually dulling over the course of years.

Can't speak for anyone else, but I use mineral oil for rubbing out the final finish(if it needs it.) You could use it for wet sanding between coats as the wood is already sealed and you would wipe it completely off before the next coat.

 

[Mark Mandell]

Whatever differences that may exist between mineral oil and various formulations of paraffin oil (paraffins are a broad class of hydrocarbons known as alkanes, the simplest of which is methane and can have essentially any molecular weight), the thing that I see as a serious problem with using any of them in any kind of wood treatment is that they will never dry and that would be a problem for any type of catalyzing oil or film finish that you might want to apply over it. Although mineral oil and paraffin oil enjoy popularity as a treatment for treenware, my opinion is that it is a bad idea. The supposed rationale for use on treenware is that they are inert. However, being inert is only one small consideration -- something that never dries will forever be accumulating contamination from everything that comes in contact with it -- that will also lead to the surface appearance gradually dulling over the course of years.

I've put poly and other polymerizing oil finishes over mineral oil with no problem so long as the excess mineral was been wiped off and was not weeping.

But I use and recommend mineral oil exclusively for treenware because the items are being continually used and washed, so any film finish is going to fail over a relatively short time and will then have to be refinished. Mineral oil, however, is gradually leached out or washed off, so a light rub with more restores the item to its original appearance (with the use-scratches intact of course). I've had people tell me that they like the look of the piece more after several years of use, washing, and reoiling. I also cook up a little "shine" out of mineral oil and candle wax. The oil penetrates and the wax gives a little low sheen that is pleasant to touch. 1 cup of oil and 1 tablespoon of wax heated up to where the wax melts and "dissolves" into the oil is fine. I then pour it into small plastic cups where it cools to a paste. The cups are recycled from powdered drink mixes.

This also completely avoids the "is the finish food safe" issue with some people.

 

[waltben]

Ditto Mark's post, but I don't buy food grade. I found horse people use the non-food grade on animals, and it's about half the price. I picked up a five-gallon bucket for about $20 back three years ago and still haven't used it all up. I also use it when turning wet wood. When I want to take a break, I'll coat the outside with mineral oil (and bag it if I can) to stop the wood drying too fast.

 

[Griesbach]

I have frequently wet sanded with mineral oil and have had no problems applying danish oil as a final finish. I do, however, make sure the mineral oil has been sanded to a dry finish before putting on the finishing oil a day or two later.

 

[Ed_McDonnell]

After more research, I still can't find any advantage to paraffin oil over mineral oil. I did find a lot of people recommending water as a good lubricant for wet sanding a film finish. It is reported to make the abrasive more aggressive than the oil requiring a little more caution to avoid oversanding.. (I guess more correctly stated oil makes the abrasive less aggressive).

I decided to abandon the paraffin oil but I had a project that I wanted to work on this morning. Didn't feel like driving to get some mineral oil so I decided to give the water a try as a lubricant. It worked great. Cleanup was a breeze. I just took the piece outside and hosed it off (the piece was finished with poly so it's waterproof at this point). I really like the results.

Ed

 

[MichaelMouse]

After more research, I still can't find any advantage to paraffin oil over mineral oil. I did find a lot of people recommending water as a good lubricant for wet sanding a film finish. It is reported to make the abrasive more aggressive than the oil requiring a little more caution to avoid oversanding.. (I guess more correctly stated oil makes the abrasive less aggressive).

Free advice, don't use it on shellac. Try a bit of cooking oil instead of your mineral oil. It'll still leave your initial coat of finish a bit softer, as the mineral oil will, but it's a good compromise between heavy oil and light water on rubbing out finishes.

 

[Mark Mandell]

Agua Pura

Didn't feel like driving to get some mineral oil so I decided to give the water a try as a lubricant. It worked great. Cleanup was a breeze. I just took the piece outside and hosed it off (the piece was finished with poly so it's waterproof at this point). I really like the results.

Ed

Water (with a tiny bit of detergent added) is the only thing I use to level hard film finishes, especially solvent finishes like shellac and lacquer and their hybrids like the acrylic waterbornes. The detergent acts as a surfactant to prevent corning of the slurry as well as help with clogging of the abrasive. Silicone carbide paper is a must. I rinse the paper often. (For reactive oil finishes, I simply use liquid finish for the lube.)

The benefit here is that your lubricant comes off easily and will not inhibit recoating, whereas oil on the surface (or in the pores) can play tricks when it's incorporated into a top coat, or can reek havok with fish-eyes and adhesion of waterborne finishes.

 

[Bill Boehme]

Didn't feel like driving to get some mineral oil so I decided to give the water a try as a lubricant. It worked great. Cleanup was a breeze. I just took the piece outside and hosed it off ........

Clever .... water can be washed off with ... water! I agree that wet sanding with water works great. It is what I have used for years on flat work. As you say, sanding with oil just loads up the paper much more quickly than it would otherwise.

I have been using linseed oil and tung oil as a finish on bowls and treenware and like them because they catalyze to a dry (if not durable) finish. Recently, I also tried walnut oil and like it because it not only has a great color, but smells great and will also dry. However, no oil finish is particularly durable on treenware if you wash it, so the treatment will need to be refreshed periodically.