Peter,
You are an expert on finishing. I have heard that if a gunstock has too much oil in it, you can use calcium carbonate to suck the oil out of the stock.
The reason that I ask is that I have some bowls that I carved from green wood six months ago, but are now dry. A few of them took in too much mineral oil during the first five days of the drying process (when I put oil on for the first five days and put them in a plastic bag for a half of each of those days.). Now I am much more careful to not put too much oil on.
But I have a few bowls which are now dry from a moisture point of view, but are still have “too much” oil on them. In other words, if you touch them, you get a slight bit of oil on you hands. I would like to remove some or all of the mineral oil.
I did some research and found that calcium carbonate could be used to take oil out of gunstocks. I have three bowls that i would like to get some oil out of – sycamore, maple and poplar. I didn’t know where to buy “Pure Calcium carbonate” so I bought a 40 bag of pulverized limestone at the local nursery (the type that sells plants, not the type that takes care of kids).
I haven’t tried it yet. I guess that it could cause discoloration, and it could possibly “poison” the bowl forever, even if I wash it out a few times with soap and water.
Originally I wanted to put a General Finishes Salad Bowl finish on them. But I found out that that is an urethane finish. I don’t want to leave the bowls the way they are, and I don’t really want to use a mineral oil finish for them. They will either be used decoratively or to put fruit in on the kitchen table (I believe). Now I am thinking of using a Walnut Oil finish.
Any thoughts or suggestions on all of this? Should I try the pulverized limestone on one of my bowls? What finish would you suggest?
Mel
Measure your output in smiles per board foot.
Replies
Mel,
My gut feeling is to use the KISS method. Have you considered a solvent wash?
I would try using some naptha. It has about the same cutting strength as mineral spirits but will evaporate a little quicker.
Have lots of paper towels at hand. I would use a heavier type towel for this.
Liberally apply the solvent and wipe it out constantly turning over the towel to reveal a dry face. This could take repeated applications and removals.
There are other solvents you could use but naptha is the least onerous to start with. You can move to a more aggressive solvent such as acetone, which evaporates almost instantly. You would need to work quickly. Obviously it is work best done outside (in the shade)
This should take care of the excess oil. You could sand with some 320 paper to see how clean the surface is. If it is still loaded, it will clog the paper quickly. I can't tell you exactly how the surface will react to a walnut oil afterwards.
Initially you could have applied a varnish or urethane that was thinned to a wiping consistency and been done with it.
Just an observation on your post; you seem to go to extremes. KEEP IT SIMPLE.
Peter
Peter,
Thank you for your advice. Ray Pine suggested using whiting (calcium carbonate). On the other hand, the KISS method may be best. I may just let the bowls go the way they are, and try some walnut oil on one of them to see how it does. I have never used it. I hear that it dries better than other nut oils, but it takes a while.Of course, the simplest solution is - nothing. Bowls for actual use are often used without any finish - oil or otherwise. Again, Thank you very much.
MelMeasure your output in smiles per board foot.
Mel,
I would try both ways and see what works best on the oil.
As far as putting walnut oil over mineral oil?? You know mineral oil never dries. Why put a drying oil over the top?
Peter
Peter,
Thanks for the update. So why should I put a drying oil over a non-drying oil?When I started working with green wood, I researched the methods of getting carved bowls to dry without cracking. I found a number of them. I met Rip Mann, who wrote a book on carving bowls, and saw his bowls. That is what got me started making bowls. I decided to try his method, and it has worked very well. I have not had any bowls crack while drying!! I am very happy about that, since it takes me about two days to carve a bowl. Rip's method of getting carved green-wood bowls to dry without cracking is described in his books. After finishing the carving, you liberally put on mineral oil and then put it in a plastic bag for a half day. Then take it out of the plastic bag for a half day. You do this for five days, then you do not add any more mineral oil or use the plastic bag again. You just leave the bowl in a cool dry place, out of direct sunlight, and let it dry. I used a moisture meter to check dryness, and it seems to be taking about five months, depending on the type of wood.So I didn't put the mineral oil on as a "finish" but as a method of keeping the bowls from cracking while drying. When I read your first response to me, I was puzzled as to a number of things you said. Did you think I was using a complicated method of applying a mineral oil finish? Well, now that the bowls are "dry" from a moisture standpoint, most seem to have lost their mineral oil. If you rub your hands over them, there is no residue. I am going to try General Finishes "salad bowl finish" on one of them. It is a thinned urethane finish that I have used on kiln dried wood. I called General Finishes, and talked to their tech guy, and asked about putting it over a bowl which still has some mineral oil that is visible -- ie, you can see its shine, and it comes off on your hand when you touch it. He said to get rid of the mineral oil by putting "furniture refinisher" on it and wiping it off. Formby's sells this, as do a number of other makers. I believe the stuff is "not good for human consumption". However I tried it on one of the bowls, and it when I finished, there was no change. So I gave up on that. Because of that experience, I don't think that the general approach of trying acetone or anything like that will work. So I have a few options. Rip Mann just uses mineral oil as his finish. He adds it every six months, or as needed. I didn't want use a mineral oil "finish" because it comes off on whatever you put it on. So I was looking for an alternative. One is not using anything. That is traditional for treenware. However, I like a little sheen (not much, but a little). So I wondered what I could do to the few bowls I have which have a bit too much mineral oil. I asked around and learned about walnut oil. Would putting the walnut oil, which dries (slowly) over the mineral oil cause any problems? I don't know. What do you think?I am also trying Watco.I am not trying to be complex or obtuse. I learn by asking and experimenting. When I have tried a number of different things, and find what works for me, I'll post a message on Knots about it. Interestingly enough, people who use green wood, each seem to have different, but strongly held opinions. I know a number of turners. It is almost like religious wars (not my style). So when I ask their opinions, I don't find anyone who has tried lots of stuff and can explain the differences and the reasons for the differences. (After 30 years at NASA, I feel the need to understand things.)When I ask for the opinions of people who don't work with greenwood about what to do with my mineral-oiled bowls, there is a tendency for them to wonder why I don't just use kiln dried wood. I know one guy who is quite ingenious and thoughtful -- he really tries to analyze woodworking questions -- he goes below the surface. His response to my question was quite thought provoking. He said that the guy at General Finishes, who recommended using a strong solvent was probably wrong, or at least, it is hard to tell. His rationale is: a solvent may thin out the oil, but that may just may make it harder to get out of the wood. He recommended trying a chemical process that will draw the oil out of the wood. That is what caused me to look up info on getting mineral oil out of wood. I found a few items on this, and they pointed to calcium carbonate. This is available at some of the nicer paint stores as "whiting". I haven't tried this yet, but I may -- just for the sake of undersanding. Hope I haven't bored you. I believe I have only used "Ask the experts" three times. I don't like to bother others with stuff that I can look up in books or the web, and test myself. I'd heard that you are quite knowledgeable about finishing, so I thought I see what you had to say. I don't consider my "situation" to be a problem. It is merely an opportunity to learn. I have a lot of options - more mineral oil, nothing, walnut oil, Watco-type product, etc. You mentioned the KISS method. That has long been my approach to woodwork, and to finishing. In science, we call it, "Occam's razor". If there are two explanations, take the simpler one. I often quote Einstein, "An explanation should be as simple as possible, but no simpler." I like that way of saying it better than Occam's razor or KISS, but they are all the same. Have fun. I won't ask you any more questions.
MelMeasure your output in smiles per board foot.
Mel,
Have I hurt your feelings? You worked at NASA for thirty years and you're that sensitive? I mentioned extremes; look at the length of your reply. Ask a question whenever you want to, I never find these boring.
A solvent could spread it but with repeated washings and dryings I feel it would help. Calcium carbonate is very useful for many things. I use it regularly in gesso for gilding. As they say there is ALWAYS more than one way to skin a cat.
Experimentation with finishing is indeed the best teacher.
Speaking of NASA, I'll be at the launch of Endeavor in November. A good friend is on board. He even gets to do three EVA'S.
Keep in touch.
Peter
Peter,
Thank you.
Enjoy the launch of Endeavor in November. I am jealous.
MelMeasure your output in smiles per board foot.
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