Blade Sealing

Why does wood splinter?

It's very simple, when you put water on wood it raises the fibers, since the glue nowadays is water based, what happens is that this water raises the tiny wood fibers and then the latex solidifies around them. When you pull off the rubbers, you also pull these little fibers that were raised by the water. VOC glue is not water based, so you don't raise any fibers when you use it on the blade. That's why many players prefer to use VOC glue on the blade and WBG on the rubber, and not seal at all. There is still a chance of pulling some loose fibers because the bond is very strong though. By the way, the first rule of removing rubbers is from side to side, not bottom to top, Butterfly used to include this information in their rubber packages, not sure if it still does. In 99.9% of commercial blades the grain of the outer ply is placed vertically, if you remove rubbers along with the grain, your chance of catching these loose fibers is much higher, if you remove from side to side you are going perpendicular to the wood grain, so it's much safer.

Even though the grain is vertical (visually speaking), very rarely the wood fibers are perfectly parallel to the blade face. If we imagine the blade on its side, these fibers will have a diagonal orientation in most cases. They will be either facing down, into the blade, or facing up, outwards from the blade. When I build a blade I try to make sure that the orientation of the fibers is facing outwards, to minimize splintering issues. I know that almost everyone removes their rubbers from bottom to top, so in this case the bottom of the fiber is more firmly secured. If the fibers are facing inwards, then the bottom of the fibers is looser, there is a bigger chance of catching it and it will splinter more easily. However, this is not easy to spot in the earlier stages of production, and sometimes I miss it. I'm pretty sure that none of the major brands is paying attention to this, so you have a 50/50 chance of the wood being position correctly or not.

Does all wood splinter?

Yes, some more easily than others. It's not good enough to say that Limba is softer than Koto so it splinters more easily. Some woods have a grain structure that makes them more prone to splintering, but that's not the only variable. It depends on the wood itself, how it was cut and the its moisture content. I will speak more about the moisture content ahead, right now I just want to mention that flatsawn wood is more prone to splintering than quarter cut, but even here it's just a generalization, it depends on the wood itself. I have batches of Limba that never gave me problems, and I had some situations with koto or even Ebony, so we also can't generalize.

Sealing changes the feeling or not?

Like with all things in life, it depends on how you do it. If your sealing your blade enough to change it's feeling, then you are probably not doing it right. Or maybe that's precisely your goal, so nothing wrong with it. Change means different, not better or worse, so you even might like the feeling of a "too much" sealed blade. Personally I don't, so I do it very thinly. I seal all my blades for security, I did have some problems in the beginning when I wasn't doing it properly, and it might even happen again if I work with a wood I'm not used too, but I haven't received a single complain since then about a splintered blade. I also don't receive feedback about the lack of feeling, on the contrary, and many costumers even ask me if they need to seal their blades after receiving them. The layer is so thin that it's actually hard to see if it was sealed or not. Regarding the feeling, there is a very simple test you can make. Just grab a piece of paper, apply a layer of sealer and let it dry. You can even go nuts on it and apply two or three. After it dries check if the paper got any stiffer or harder. A piece of paper is roughly 0.1mm thick, a layer of sealer is microns thick, 1/10 of the paper thickness, so don't tell me you feel a difference. If you use the proper stuff, it's designed to respond to natural wood movement, so it's relatively flexible, of course if you put on thick, glossy coat of epoxy of whatever, you will feel a difference.

Another side note here as well. Old blades feel different, not because of water or glue or whatever, but because they are old! Wood doesn't get drier with age it depends on the environment! Wood has a natural moisture content, and it will continue to make moisture exchanges with the environment unless it's sealed. If you store your blade in a very dry environment, with a lower moisture content than your blade, it will progressively release moisture into the air. On the other hand, if the environment is very humid, it will continue to absorb moisture. Another aspect is the type of glue used. Nowadays we use poly or other polymer glues that are very stable, but for other water based glues like Hide, even after they have dried, they will slowly continue to cure over time. Sometimes they even become too brittle and lose their properties. And let's not forget the impact of the ball. It may not sound like much, but the constant impact of the ball over the years, does change the properties of a blade. It's like using a tiny meat tenderizer on your steak.

Water is your friend!

You just need to know how to use it. I see a lot of people saying that over the years, water seeps into the wood and changes the feeling. Another little test for you, take a piece of wood veneer, usually 0.5-0.6mm thick, and try to dye it. Apply all you want, leave it overnight, do whatever comes to your mind. You won't be able to get the dye to penetrate even halfway trough the veneer! It's actually very hard to dye wood all the way through, and that's why I need to buy expensive pre-dyed veneers to make handles, because this is a specialized process that requires vacuum chambers. Wood makes moisture exchanges with the environment through the end-grain. Think of the wood grain like these tiny little pipes, water mostly gets in or out through the end of the pipes, not the surface of the pipe. Sure, if you put some water on wood it will be absorbed, but it gets out as easily as it gets in.

This is actually the most crucial step, and you may even get away with not sealing your blade if you really don't want to. Before sealing, you must make sure you raise those loose wood fibers I spoke about earlier, and sand them. I apply this step to every blade I make. Very simple, just take a wet cloth and damp the surface of the blade, let it be for a few seconds until you see the fibers getting up, dry it out with a hair drier, then gently sand them away. Be sure to sand them in the opposite direction they are facing, you want to cut these fibers, not to force them against the surface again. After sanding be sure to clean the dust and you are ready for sealing.

Sealing

First, what to use. I'm not gonna tell what I'm using because it's a local product and you won't be able to get it, but it doesn't matter anyway, there are plenty of brands out there. Oil based is probably better, you are minimizing the amount of water that gets into your blade (but we've already seen that's not a problem), but it takes forever to dry! I'm sealing many blades at once, and I can't afford to wait days for this stuff to dry, so I use a water based poly. We don't call it that here, it's acrylic lacquer or something similar, you can find it with many names. Generally they are all similar, it's a milky white stuff and they come in various degrees of viscosity, but you also don't want something too thick that's harder to spread. It's very used for guitar finishing, kitchen counter top protection, and generally cheaper than the ones sold by TT brands, but you can use those too of course.

Applying it is very easy. I just put a small amount on the blade, about 2cm in diameter and spread it with a small sponge. You can use the same sponge you use for gluing. If it's summer I wipe it off right away, this stuff dries very fast, if it's winter I will let it sit for a few seconds then wipe off the excess. For cleaning you can use a clean, lint-free rag, or even a paper towel, just be sure it's resistant, otherwise it will leave white spots on your blade. Also, be sure to wipe in a vertical movement, along with the grain of the wood. Just repeat on the other side and seal the edges as well while you're at it (you might have to remove the glue first if the blade is used). It will be dry to the touch almost immediately, but if you take an hair dryer it will completely dry under a minute. Because you've already sanded the blade before, you won't get any raised fibers and won't need to sand anything else, but I generally use a green scotch brite pad just to take the shine off. Again, vertical movements along with the wood grain. That's it, you are good to go.

Sealing creates a very thin layer between the wood and rubber, it's natural if you don't get such a strong bond as before. It still should be strong enough for the rubber to stick properly, so if you found you did it a bit too much, just take a piece of 180 grit sandpaper, and very gently sand the surface to create some roughness. Again, vertical movements along with the wood grain.​