Can I get some advice from a luthier (wood treatment, offtopic)?
Hi, this is kind of off-topic but since luthiers work with wood and know a lot about it (I guess), I think some of you can help me. I am building a desktop which consists in two big high quality squared metal legs and a plain plank/table/board of wood, which happens to be pine.
My question is fairly simple: which treatment would you use to finish the board?
It's going to be a desktop for studying, writing, etc... I have basically 4 different "ingredients":
1. Wood sealer/varnish primer/seal coat: it's a white liquid that seals the wood (becomes transparent when you apply it), avoiding humidity to enter and affect the wood overtime. Helps as well the varnish to stuck well, be efficient and spread evenly.
2. A trick from a local luthier: paraffin oil, that you use in untreated wood, such as a fingerboard or fretboard, that basically is a wood sealer, like number 1. It is way more "oily" though, darkens the wood more, but it makes the wood look gorgeous and shiny, unlike the number 1, which barely changes the wood color and beauty.
3. Water-based varnish: I have heard about them a lot, but never seen or used one myself. I bought one the other day, and it's something I was not expecting. It's an opaque liquid, with a gel-like texture, like "cold" custard that is starting to solidify. Really weird, even after shaking it a lot, stayed the same. Nevertheless, once you apply it to the wood it becomes an easy to use varnish, but the texture really shocked me.
4. Your old time "regular" varnish, I guess it's called "synthetic" varnish, your typical translucid, honey-like texture varnish. I've just read that they are older and "worse" than water based varnishes. Apparently it is WAY more shiny than the water based one.
So, here's what I was going to do: first, sand the board so I have a very smooth surface. Then, I prefer the number 2 sealer, since it darkens a little bit the pine and makes it look "alive". The problem is, it's oily, unlike the other primer, at least for the first 2-3 days, and I am not sure if the varnish will work over that. I've always used the paraffin oil as the finish to raw wood. Or may be it's compatible with water based but not synthetic, or viceversa.
Once the sealer is applied, I pretend to use the water based varnish, 3 or 4 layers so I get a shiny finish.
I'd love to read some comments, if you knew about paraffin oil (not many people know about it), and basically if I am good to go.
I'm afraid the ancient Cremona secret is supposed to have been buried with Guadagnini! But one characteristic it had: When you rested your hand on one of their violins and then took it off, the surface would be misty.
I'm not a luthier either -- not by any stretch. However I have made myself a few writing-desks and other pieces of simple furniture (end tables, etc.). My preferred surface wood is birch because that is readily available as a plywood veneer, and it takes finish beautifully.
I wouldn't use paraffin oil (which we call "mineral oil" in the US) for two reasons:
I wouldn't flatter myself to call myself a luthier—I've just fixed a couple instruments and built one. BUT:
If you're going to consider instrument finishes consider something designed for high wear like guitar finish.
Pine is notorious for blotching. My suggestion, is use ZInnser sealcoat (dewaxed shellac) as a sealer. You may or may not want to dilute to to 50/50 with denatured alcohol. One coat. Then use General Finish Gel Stain. Then after a few days to dry, use General finish Gel Varnish, at least 3 coats. This should give you a no blotch, protective finish, that is easy to apply and predictable results. PRACTICE on a piece of scrap. I've refinished more new projects than I care to admit.
OK, I'll forget about the mineral (paraffin) oil. Quick question here: why is it then recommended when finishing fretboards and fingerboards?
Oh, so with high dense hard woods such as ebony or rosewood, the paraffin mineral oil works, right?
no parrafin oil never works because it never dries
Of course the violin is sealed, otherwise the varnish would seep into the wood and make a mess of things. I once visited a local maker who used oil varnish and didn't use a ground... his entire lineup of instruments sounded like it was stuffed with socks. Just ruined. His wife, who did seal the plates, made very nice-sounding violins.
Lyndon, paraffin oil MUST work with ebony and such because my local luthier has personally told me that's what he uses to finish the fingerboards and fretboards of his instruments.
No respectable luthier uses parrafin oil on fingerboards.
It will never dry and will gum up the windings on the strings
Paul, what happened is that the mineral oil soaked in, and was absorbed to the point that you could no longer feel any on the surface. It didn't dry, unless you waited at least several hundred years.
Thanks for the explanation, I was imagining something like that about the term "dried". In hard woods, anyways, my luthier does not put an insane amount of oil that will soak the entire fretboard or fingerboard all deep through. It's just the surface, you put some of it along all the surface that's visible, let it "soak" for a few minutes, and then you start rubbing with a hard cloth, like jeans. There is no way at all that the oil is going to go all the way through the ebony or rosewood and reach the glue, spruce, maple... You do not deep fry the hard wood in paraffin oil.
David, I saw "Stand Oils" mentioned elsewhere - I believe these are drying oils that have been stood at a high temperature with comparatively little access to air (e.g, in a covered saucepan or pot), so that they polymerise, and then, when applied take longer to dry, but by the same token the dried surface takes far, far longer to be weakened by further oxidation. Is this, in fact, the case?
"Can I do all the layers of seal and varnish in the top and sides, and when that's finished and dried, unmount it and do the bottom side?"
> There is no way at all that the oil is going to go all the way through the ebony or rosewood and reach the glue, spruce, maple
I mean, what are we even talking about here?
Paul, Han Jin is right. And you are also correct in that total through-penetration of mineral oil on a one-inch piece of wood won't happen right away, or nearly as quickly as on a piece of paper.
Some woodworkers will use parafin oil on chopping boards and bowls because it is claimed to be food safe. And they end up with a surface that always feels a bit sticky or oily because the oil never hardens. It will serve the purpose of protecting the wood against (temporary) water contact, but it will always be sticky. Drying oils - like linseed oil, tung oil and walnut oil - will polymerize inside the wood (or on the surface if you apply too much) and give a similar protection while avoiding the sticky feeling. Varnish will build up a film on the surface.
It is not "claimed" to be safe for human consumption, it is safe, basically because I know it's used in pharmacy.
It's a bit strange that you ask questions about mineral oil, and then seem to object when people attempt to answer them.
I am sorry if I misused the word "claimed". What I mean is that it is marketed as food safe - basically implying that the alternatives e.g. linseed oil are not. Go ahead and use mineral oil on wood if you want to - I wont.
Let me explain myself: I created this so I could receive some help with the wood problems. That is and was my main target.
It seem you didn't come here to learn anything at all, but rather to lecture us with nonsense!!
If you want to un-twist a board just wetting it will not do. You need heat. Steam the board, force it into place and let it cool.
It will probably initially go convex. Upon thoroughly drying, it may end up concave. Part of this will depend on how much the product contracts upon drying. Good idea to test first.
A related question, which has always puzzled me: why is the interior of a violin never varnished, and is always left untouched?
Trevor, some makers do put something on the inside. When it is not done, the notion behind this is often that the added mass is bad for the sound, since there is not enough of an increase in stiffness to make up for the added mass.
David, thank you!
Lyndon, the only one talking nonsense and even trolling here is YOU, and only you. Stop coming to say one stupid sentence to provoke, you always behave like this for what I've read, I don't know why are you here.
The catch is tonewood is seasoned and doesn't instantly twist into a knot when introduced to moisture. There are examples of historic violins with twisted necks and things because they were carved from "green wood"... either that or luthiers were drinking a little too much back then.
But if I let it dry, with the forces of course applied in the opposite direction as I have done, it's like heating the wood but at a very slow rate, isn't it?
Phew! Reading this thread makes me downright glad that I'm an inferior woodworker relegated to making every large, flat surface out of veneered plywood!
Paul D, some makers use chemical "driers" in their oil-based varnishes. I don't, because questions remain about many of them ever ceasing to do their thing, which raises the prospect of a varnish more quickly reaching a nice state, but also going downhill more quickly after that. Some of them are also poisonous or toxic. Lead is one example, which is no longer allowed in paint.
OK, wait a second.
To permanently bend wood - so it will retain its shape without being bolted to a steel frame - you need to soften the lignin by heating it, bending it while hot and let it cool. This is done with the ribs of a violin and it is done with the 2" thick oak boards of a wooden fishing boat. The difference is the time it takes to heat that wood and the force it takes to bend it. A large board such as yours is difficult. You would need to build a box to surround the board. This could be done with construction plywood. And then feed steam into that for a few hours. Finally clamp the board in place and let it cool.
Now that's way more helpful, appreciate it! Nicely explained!
Paul N. wrote:
Oh, very nice! That is amazing!
I often straighten warped bridges by moistening the concave side (which will expand it), and heating the convex side, which will dehydrate and contract that side, while also softening the "internal glue".
The lignin I mentioned is the "glue" inside the wood. You basically have to heat it all the way through. That's why it is quick with a violin rib but takes a long time with a big board like yours. I am afraid a hair drier is not going to cut it.
David I agree that the UV-curing approach sounds much better. But I appreciate knowing that driers have been employed too.
To fix the slightly concave surface of the table I wet with water the top area. After a few minutes/hours you can see the differences, which can be a lot if you don't do it carefully.
Perhaps you could try an iron? With a wet towel between it and the table.
Paul, your strategy of moistening and tweaking alone may do the job. It's hard to know, since when lumber is dried from its living water-content state, stresses are inevitably incorporated which further moisture cycling can release, and these are not always fully predictable.
Or an iron, that's right!
Since wood air-dries from the outside in, the outside will initially dry in expanded state, held in that state by the not-yet-contracted wood on the inside. Later, when the inside dries, it will be held in an expanded state by the drier wood on the outside. It may take several moisture cycles to get the wood to it's final contracted state. (I've oversimplified this a bit.)
Yeah, I'm familiar with those cuts. So... how would you proceed with an iron?
Since your board appears to be made of glued-together strips, which could have the grain running all sorts of directions, it's hard to know what to recommend next. Before using heat though, do you have a way of knowing that the glue holding these strips together won't release when heated?
Oh... you are right. I didn't even think of that, that's why you are a luthier and I am not, hahahaha. The glue looks pretty good, the pieces are joined really well as far as I can tell. If I am not wrong I think I saw yellow traces of glue, really similar to those from the great Titebond glue, but I highly doubt they used a glue that expensive. I mean, even though I bought real wood, the whole piece was like $40 or so.
Titebond is often used in modern guitar construction, and heat, or some combination of heat and moisture, is used to release it.
I thought it was one board. If it is glued of several strips with PVA glue forget about what I said.
Hahaha, so I forget about heating it?
Nothing, I think the iron even at maximum is not enough to correctly heat a 1 inch thick board.
"I didn't thought it would be this hard." You are working against the forces of nature. I also didn't know your board was joined. That certainly doesn't make the problem any easier.
Don't underestimate the forces of wood. Oak floors that have been laid down with too little distance to the walls have been known to move the walls when expanding as humidity rises. Even when screwed to the floor joists!
Guys, I finally made it, I wetted both sides and applied a counter twist that was the most extreme of all of the ones I did. I also ironed the bottom side although I don't believe it did anything important. Now it's finally sitting flat naturally, though it is still conserving some internal twist force because two corners get lifted way easier than the other two.