Wet sanding question

[Trevor Mills]

I use power sanding for bowls but I've been wet sanding platters and enjoying the absence of dust. I've been oiling the platter and soaking the sandpaper in walnut oil. It makes a nice slurry and works quickly but walnut oil does get mixed up in the wood chips around the lathe.
i realize walnut oil is flamable but do I need to worry about spontaneous combustion the way I would with some other oil finishes?

[John Keeton]

I never leave wood shavings in my shop overnight. Just takes a few minutes to shovel up the bulk of it. The dust and deep cleaning wait until I am done with the piece. I honestly don't understand having knee deep shavings around a lathe. Aside from losing small items, it is a safety issue in many respects.

[Eugene Dixon]

Shavings in the shop floor make a good place for snakes to shed. Don't ask me how I know.

[Bill Jobe]

I thought wet sanding when referring to wood meant water. I like to dry sand it to 2000, then wipe it with a wet cloth, when it's dry sand it again with 2000, then sometimes again. Then let it dry and sand it with a paper sack. That gives me a very smooth finish.

Is wet sanding with oil the only thing wet sanding means?
What finishes can be used and what finished cannot be used?

A few weeks back a member spoke of submerging a piece in (I think) walnut oil for several days or perhaps weeks. What does that process do and, again, what finishes can and cannot be used on top of that?

My apologies for my somewhat off topic text.

[Paul Williams]

I'm not a neat freak (like John) but I always clean up the shavings after turning and before sanding wet or dry. I think my motivation is to keep as much dust as possible out of the switch and speed control on my lathe. I also don't like to track the chips or dust out of the shop. I like the finish achieved by sanding bare wood with oil, or oil followed by shellac and finished (burnished?) with shellac and just enough oil to keep my paper towel from catching and tearing apart. When I wet sand a finish I use water.

[Trevor Mills]

I do sweep up and vacuum after every turning session, but the question I have is "do I have to worry about spontaneous combustion with walnut oil? The chips I'm sweeping up are going to contain some walnut oil and a potential fire in a trash bin is my concern.

[John Keeton]

I don't think I would put oil soaked anything in a trash bin. Can't you mulch somewhere with the shavings?

[Grant Wilkinson]

From what I've read, walnut oil, like many other oils, dries by exothermic reaction - it creates heat. If you have enough of it and the air supply is limited, I believe the heat it gives off could cause flammable material around it to spontaneously combust. We were taught to hang our oil rags on a line or lay them flat on the cement floor until the oil was dry and hard.

[Trevor Mills]

Thanks Grant. That's the info I've been looking for. I'm always careful with oily rags but didn't know if walnut oil needed to be treated with as much caution. I'll treat it the same as I would any other oil finish.
Thanks everyone.

[Reed Gray]

I have been using walnut oil for over 10 years. Spontaneous combustion is a major problem with most of the furniture oils that have hardeners and/or accelerators in them, and left in a pile, they will ignite in a few hours to over night. With the walnut oil, this does not 'appear' to be a problem. I made a point of piling them up in the gravel outside the shop to see what happened. Results: nothing, not even warm to the touch. Walnut oil takes a week plus to cure, where most furniture oils are dry to the touch in 12 to 24 hours. What little heat walnut oil generates, is able to bleed off way before it can reach combustion temps. Note here, I am not saying it can never happen, I am saying I tried to make it happen and it didn't, kind of an 'individual results may vary' situation.

I don't care for wet sanding. The slurry tends to cover scratch marks and tear out, especially in darker woods, and you don't realize till after you are done sanding. Some really like it, especially for the more toxic types like rose wood. I would rather deal with the dust than the oil sludge.

robo hippy

[Trevor Mills]

OK. Thanks Reed. .. Back to where I started.
i like wet sanding when I want to keep sharp edge detail and tight contours. I remove all the tear out with a NRS and do preliminary sanding with 120 to remove tool marks, coat the bowl with walnut oil, then sand by hand, keeping the paper wet with oil. It creates a sludge and seems to cut quickly.

[Leo Van Der Loo]

Trevor, polymerizing oil rags can become hot, because the polymerizing is an reaction with oxygen in the air, and then heat can build up, thereby increasing the reaction with the oxygen, if this is fast enough the rags can spontaneously combust.

So Polymerized Tung and Boiled Linseed oil (BLO) will react with oxygen fast enough for this to happen, Walnut oil without accelerators will not do this, as Walnut is barely a hardening oil, and it takes forever to get there, I would say it is not a hazard, but then again, I would not take chances and get rid of the rags or your sanding dust, yes rags outside will probably get cooled enough but hung up on the wash line is a better away or just burn them in your wood stove right away :).

Just drying finishes do not react with the air, as there the volatiles like thinners just evaporate, no heat from that.

[John K Jordan]

Is wet sanding with oil the only thing wet sanding means?
What finishes can be used and what finished cannot be used?


Bill, I like to sand with oil in certain circumstances. The wood/oil slurry can fill in open pores and leave a smoother-looking surface. I only do this when I'll be applying oil as a finish or as one step in a finish. I have also sanded with water on trouble spots. I haven't tried sanding with any other liquid or finish - it seems like most would dry or set up too fast and make a mess. I know people who say they've sanded with paste wax.

I've never heard of soaking in walnut oil. I've never used walnut oil on a turning. I have saturated things with Watco oil in a plastic bag as the initial step in an oil finish.

JKJ

[Leo Van Der Loo]

I thought wet sanding when referring to wood meant water. I like to dry sand it to 2000, then wipe it with a wet cloth, when it's dry sand it again with 2000, then sometimes again. Then let it dry and sand it with a paper sack. That gives me a very smooth finish.

Is wet sanding with oil the only thing wet sanding means?
What finishes can be used and what finished cannot be used?

A few weeks back a member spoke of submerging a piece in (I think) walnut oil for several days or perhaps weeks. What does that process do and, again, what finishes can and cannot be used on top of that?

My apologies for my somewhat off topic text.

Bill water or oil can be used to do the wet sanding, though wet sanding brings rust into play, plus your wood will absorb water, and so you’ll have to dry it again.

If you use the same oil as what you will using to finish there is no problem of waterwet or rust, some even use paint thinner to sand with, anyway I tried it and didn’t like it, besides I don’t have problems with dry sanding.

About soaking in oil, that is done to get translucency in things like NIP (Norfolk Island Pine) see pictures, it is a time consuming process, but if done well, the outcome is mesmerizing

If you want to know more about Ron Kent and his process, here’s a link to that.

http://www.ronkent.com/index.php

353247 353245 353246

[robert baccus]

Wet sanding(water) is very useful on film finishes especially although It works well on wet woods also. Very useful in sanding hard, oily tropicals and "rich lighter pine" as well. My lacquer finishes get wet sanded(water and light soap) with 3-M fine grit sponges to kill any dust motes or orange peel. After this it has a fair matt surface which is easily taken to a full gloss or any duller gloss with white plastic wool and various liquid auto compounds. Now I'm dizzy too. There are some great compound/wax liquids available as well. Wet sanding prevents buildup on your paper 0r plastic wool and stops scratches and goes much faster.

[Paul Williams]

Back to the issue of spontaneous combustion. I wonder if oil in shavings might not be worse than rags. It seems that the shavings make a nice insulator and keep the developing heat in the pile. I realize that a pile of rags would do the same thing, but I have never seen a pile of rags, only a few spread out on the floor. If you wet sanded as bowl and then turned another bowl without clearing the shavings that contain the oil, you would be insulating the oil soaked shavings. Unlike Reed, I am not going to try that, not even outside.

[Leo Van Der Loo]

Back to the issue of spontaneous combustion. I wonder if oil in shavings might not be worse than rags. It seems that the shavings make a nice insulator and keep the developing heat in the pile. I realize that a pile of rags would do the same thing, but I have never seen a pile of rags, only a few spread out on the floor. If you wet sanded as bowl and then turned another bowl without clearing the shavings that contain the oil, you would be insulating the oil soaked shavings. Unlike Reed, I am not going to try that, not even outside.

I would believe that is not the case, as for the polymerizing to keep going faster, there has to be Oxygen, lots of that in the loose pile of rags, not so in the closely packet shavings and sanding dust, but as I said before, I would not want to take the chance by waiting with something that has to be done anyway, cleaning-up.

[Bill Jobe]

Have you ever tried powdered silk?

[Bill Jobe]

Thank you for the link, Leo.

[Bill Jobe]

I just might give silk a try. I happen to have some on hand.
Not sure whether to mix it in water or an oil.