Blade sealing

Thanks as always, guys, for the opportunity to discuss such questions.

i work part time in a TT pro shop changing rubbers for people, selling many different brands of blades, sealing, repairing, and observing over time. I have a background in fine woods, glues, and sealants, so this is something i have looked at closely and have more-than-average experience in.

i almost always seal my blades, because i don't like to risk damage. The new non-VOC glues are water based, and wood--particularly solfter wood like limba--doesn't do well with water put on it. Small splinters come up when the water hits the blade, and when i peel the rubber off, splinters and even chunks of the delicate top ply tear away. The damage is always worse the second and third time. There is never a fourth: the blade is destroyed by then.

And brand is no guide in my experience. I replaced the rubber on a Butterfly Timo Boll OFF- two days ago. Butterfly blades, particularly the more expensive ones, often don't seem to require sealing. Many of them have koto top plies, which is harder and less water sensitive, and Butterfly blades are really well pressed and glued together, as well as carefully sanded at the factory to avoid protruding splinters. This particular Boll OFF- was having its second set of rubber attached, and when i took off the first set, it ripped shreds off the top ply. I doubt it will survive the second rubbers being removed. I have seen this more than a few times with all sorts of brands, particularly the mid-priced blades.

I personally use a Stiga Clipper Classic ($50).  In my opinion, one would have to be insane not to seal Stigas. They are fantastic blades and very reasonable for the quality you get; but they come rough from the factory, and their top plies react badly to the water. Try and experiment and see: feel the blade out of the box, how smooth it is. Now run a lightly damp paper towel over the surface, leave it for two minutes and feel it again. if your experience is anything like mine, you will feel splinters that weren't obvious before now protruding. so i LIGHTLY sand them down with a fine grit sandpaper (120 grit or finer), then apply a light urethane sealant to it. For most blades, one coat seems to do it. On my Stigas, i use two light coats. To the naked eye, you can't tell anything has been applied, and i don't detect any change in the playing characteristics (i have tested, using a blade, sealing it, then using it again. Felt identical.) 

the sealants from Donic, Tibhar, etc., seem very heavy to me, more like varnish. They add weight and another layer to the blade's plies. The same goes for the varnish jobs i have seen done by the major equipment catalogs that offer blade sealing for a small fee. That is why i prefer light polyurethane finishes. I personally use a product called Rejuvenate Professional Urethane-based Wood Floor Restorer (available on Amazon.com, among other places). I am confident other polyurethane sealers would be as good. Tell the employee at the hardware store what you are doing, that you need a light urethane sealer for a bat made of delicate wood veneers, and you don't want anything heavy, just to seal and protect,not to varnish.  They should be able to help you find your local version of what i use.

Does it make gluing harder? Absolutely. The sealant blocks the glue from soaking into the top ply--as it is supposed to. The downside is, then the glue doesn't grab the wood as well on light contact. If i am gluing a blade that has been sealed, i do it differently from what the glue instructions say, particularly if it is a blade i have sealed with two light coats. I do what is sometimes called "wet gluing": i apply a thin layer of water-based rubber glue to the blade surface and back of the rubber as usual. But rather than waiting for the glue to dry to clear, i let it dry only a short time, so that it isn't watery, but not yet firm either, the consistency of rubber cement just out of the bottle. I roll the rubber on the blade, then immediately put it in a click press or under a foot-high stack of books. I leave it for 30 minutes, then pull it out, cut the rubber, and do the same to the other side. Then i put the blade under the foot-stack of books for a few hours, or overnight, just to be sure. The pressing forces the still-soft glue down into the crevices of the sealed wood. The result is rubber that is firmly stuck to the blade, more so than if i hadn't sealed it at all. It's more trouble certainly, but it saves my blade and gives me a GREAT glue job, so i don't mind. 

A caveat: wet gluing is a terrible idea if the blade is NOT sealed. You will trap the water from the still-wet glue against the blade, and the top ply will be damaged. 

Hope my experience on this is useful to you guys!

I'm using water based acrylic spay varnish, the one used for sealing/protecting paintings, any experience with that product ?

Hey Alois,

My blade is cracked and need to know how to fix it.  Its the part if you were to go up the handle to the blade where it curves out to the blade its where that curve is.  Can you help me?