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I Forge Iron

Wood Treatments


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So the more I read here the more I see some really old school techniques for all kinds of stuff, I want to learn more but I also want to share what little I know from working in a paint shop many years ago.  

So if you want to preserve a chunk of wood, understand what it will be used for.  If it's a fence, you have things like Thompson's water seal, which works fine if you re-apply regularly and it's fairly cheap.  Exterior woodstains also do a good job, imparting color, but most of those can't be walked on.

Polyurethane's vary, but most do better inside, and most require a very thorough surface prep to come out right.  It ends up being very tough but will likely yellow with age.

Laquers and varnishes are great for ultra smooth finishes but often have to be applied in multiple coats.  Not like 2 coats, more like 6 or seven, with tedious sanding in between.  They also aren't all that tough.  

that's what I learned working at the paint shop, but coming here I learned there are other really old school techniques

I have heard about Tung Oil or Linseed oil, neither of which ever came up working at the paint store outside of the two old guys who came in and bought a gallon once every 2 years, so I wondered what do ya'll use for treating handles or other wooden things and how long do they last?  Google only goes so far and does not trump experience.

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Wood handles for knives; I like tung oil with as many applications as you can stand!  Don't know how long it will last in normal use as so far it's doing better than I am; got a piece done about 37 years ago still going strong on it's original application.

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Tung oil and linseed oil (specifically "boiled linseed oil" or "BLO") are both in the same family of wood finishes -- that is to say, the oil finishes (surprise, surprise). Both work by soaking at least partly into the wood and then hardening; subsequent coats build up a thicker film for a higher finish. Both are vegetable oils, with tung oil coming from the nut of the tung tree and linseed oil coming from the seed of the flax plant (the stems of which produce the fiber in linen).

Both tung and linseed oil harden by polymerization from exposure to oxygen. Tung oil dries faster and harder than boiled linseed oil and is generally more durable. Linseed oil often has metallic driers added to it to shorten its hardening time. Raw tung oil has a satin sheen to it, but you can get "polymerized tung oil" that can be rubbed to a much higher gloss.

Both tung and linseed oils have an amber color, so neither is great when you want an exceptionally blonde finish on a light material such as ash, maple, or bone. However, it does give some extra warmth to reddish and brown woods, such as cherry or walnut. Dabbing some on a scrap of your material will give you a good idea of what the finished piece will look like.

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They also allow "repair" to a damaged finish.   For linseed oil; exposure to UV can help speed up the polymerization. I use sunlight, people faking old masters oil painting have used UV bulbs...

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Posted (edited)

Part of why the topic came up is I am thinking of doing a couple of things, one is to trim back some branches on the huge silver maple out front of the house.  When I do that, I will likely have several  sticks that I can use to make walking sticks or canes.  On the walking sticks I think I may use a couple to tie staff slings to.  I think it would be nice to put an old school finish on them.

I have some BLO on hand.  My wife has some for use with oil painting.  I think I may just buy some tung oil too, to compare the finished surfaces.  I also have some polyurethane, but I dunno if I want to go that route.

Thanks guys, and I hope this info can help some other folks

Edited by Paul TIKI
added something I forgot
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Whatever you do, make sure you let whatever application rags or paper towels you use dry COMPLETELY before you throw them away. The oxidation of the oil is exothermic, and it can put out enough heat under the right circumstances to cause spontaneous combustion. There was a high-rise fire in Philadelphia twenty or thirty years ago that was caused by linseed oil-soaked rags; three firefighters died.

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A blacksmith up in Albuquerque worked with a painting contractor that refinished a gym floor and then burnt the place down with the used rags.  It's a KNOWN Danger.  I throw them in the coal forge firepot.  If they catch on fire I might not notice.  If they don't they are starter for the next fire in the forge.

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5 minutes ago, ThomasPowers said:

a painting contractor that refinished a gym floor and then burnt the place down with the used rags.

I heard of some folks who put several years and many thousands of dollars into building their dream home. After they finished oiling the floors, they went out for a celebratory pizza and came home to a smoking cellar hole.

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To give an idea of the amount of heat released while polymerizing, polymerizing oils like Tung oil or BLO release about half of the heat that would be released by straight up burning the oil. That's certainly more than enough to light the rag on fire, and the only reason they don't always ignite is if the heat is released slowly enough to transfer out into the surroundings. The issue is if the rag is insulated and the heat can build up (like a tightly balled up rag, or buried under other insulating material in a trash can)

Whether linseed oil is boiled or not shouldn't really affect the total amount of heat released as it polymerizes, but the critical difference is the rate at which the heat is released (much higher for BLO).

I believe I read somewhere that the oils continue to release quite a bit of heat even after polymerizing to the point of the rag becoming stiff. So be really careful about throwing rags in the trash that "feel dry".

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i just bough 1 L of BLO off amazon has lasted me since November last year with 1 knife and multiple hammers redone for almost no show on level drop i am happy with it though my mother says it stinks

M.J.Lampert

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I accidentally bought multiple quarts from Wally world. I think I have three quarts of BLO now or I've discovered three so far anyway:wacko:. I wouldn't be surprised if a couple more show up. 

Pnut

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Both tung oil and linseed oil are good for finishing forged pieces, especially when thinned with mineral spirits or turpentine and wiped on a wire-brushed forging at a black heat. 

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11 hours ago, M.J.Lampert said:

you will have enough to last the rest of you life timeB)

I was thinking the same thing. And yes it does stink. I had some hammers soaking upside down in an aluminum take out dish in my tiny apartment and it wasn't pleasant. I had to relocate them to the fire escape. 

Pnut

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I use beeswax and turpentine sometimes with carnauba wax added for most wood, with birch tar if I want to darken - sanded and polisoir burnished (tight bundle of waxed straw end on) , if I'm in the mood I'll mix up some shellac and go for the full French polish. 

 

 

 

 

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My late grandfather was a crafter/carpenter and the one thing I noticed he always did after staining/sealing something was take his rag pile out back and burn it. Never touched a trash can or anything else. When he was done with them they were laid out on the bench and when he was done, he would gather them all up and take them out back. Never really knew why until quite a few years later.

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I make my own wood finish for things that will see weather by using various combinations of boiled linseed oil, turpentine, soil-based stain and spar varnish.  Generally equal parts of each is a reasonable starting point.  Often for the first coat I omit the spar varnish and up the turpentine a bit so the oil penetrates better, and then add spar varnish in on the second coat.

An interesting finish is to paint on iron acetate made from a solution of dissolved steel wool in vinegar.  High tannin woods like oak turn black, deeply.  Then you can oil or wax as you see fit.

I am intrigued by the possibilities of blending pine tar into some of the formulas that I use.  No recommendations yet on that.

One other suggestion is to leave the wood, especially hardwood, somewhat rougher...say 120 grit.  Then put the first coat on to allow the oil and solvent to penetrate more deeply.  You can then sand it to the desired final smoothness when it is semi-dry.  This helps fill some of the pores for an even more durable surface.  Final coat with formula using spar varnish.

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