After the last coat of glue is thoroughly dry, use a knife to cut and scrape away most of the extra glue. You may find that some places need another application of glue. When the crack is getting almost invisible, sand with 250-400 grit black wet/dry sandpaper. When you are happy with the result, you can polish up the area with steel wool moistened with bore oil. Then use bore oil on the whole instrument.
Most of the time, the cracks I see are not big enough to allow light to pass through. Such cracks will very successfully be fixed using Superglue. The glue seems to both stabilize and repair the crack, as well as being cosmetically perfect. For hairline cracks, before gluing, take a sharp knife point and gently run it along the crack in order to widen the crack a bit. I know you will hate to make the crack worse, but this will encourage the Superglue to penetrate deeper into the crack.
I recently [3Feb2011] have had an interesting e-mail conversation with Silverio in Patagonia, Argentina, mainly about his Lerue clarinet. He told me that he had to go to the hospital and could have died from poisoning with ebony or cocobolo powder. He says to use hard rubber powder, and says it bonds much better with the superglue. [18Jan2012: I am preserving Silverio's comments here, but after personally trying hard rubber powder, I still like grenadilla powder much better. I found that the hard rubber powder did NOT mix well with the glue, and the glue did not harden properly. Thanks to Fernando in Berlin, Germany, for the translation!]
I always will mention if any glue has been used on one of the instruments I sell on eBay. If one of my glued instruments cracks again, I will repurchase the clarinet at a fair price that reflects the months of use since the sale. (Details found at the end of eBay Policies.)
This page was started in response to a question I received from a member in France.
Subject: Buffet Crampon full boehmPhil Pedler's Response:
Thanks for becoming a member of clarinetpages! ... [Brackets show Phil Pedler corrections.]
I assume the hole on the back that you mean is the thumb hole? Or do you mean at the register key. Obviously, if it hurts the playing, it is leaking air. So the trick will be to find some way to stabilize the instrument so that it doesn't crack anymore, and fill in the crack [or temporarily tape it] so that it doesn't leak, and at the same time allow for some flexibility. You want the instrument to be able to adjust slightly for different temperature and humidity.
I am only an interested hobbyist, and this sounds like the kind of problem you will want to take to a top repairman. The traditional fix for your instrument is to have it banded with a steel band. Serious cracks sometimes additionally require the insertion of pins in several places. I don't have the equipment or know-how to band an instrument, and don't have experience in pinning. [See Pinning cracks.]
Buffet doesn't build many full Boehm instruments, so yours is worth a fair bit even though it sounds like an old serial number. If the F is part of the serial number, it is pre-1927, or if not, it could be 1964-66. The 64-66 horns bring higher prices now.
If an instrument this old has just recently cracked, I bet it is because of storing it in a very dry environment, together with not playing it regularly or oiling the wood. Don't oil the wood now. Let the technician who will repair the instrument decide what is best to do.
If you decide to do something so that the instrument can be played now, you might try filling the crack with wax. Wax can be removed later, whereas epoxy will be nearly impossible to get out later. Wax won't get too hard, so if the instrument contracts, it shouldn't cause the crack to get larger. I think it is better to wait until a qualified person helps fix this!
[NO! It would be better not to use wax. I was meaning paraffin, not bees wax. I think either might leave an oily residue that would interfere with later gluing. Covering with electrician's tape might be a better temporary fix to seal up a leak. I agree with one woodwind.org participant who said that superglue is safe and will help stabilize a crack.]
[Jan2015 update] Andy Beals sent this helpful info: I was reading your "Help for Cracked Clarinets" page at http://www.clarinetpages.net/stuff-phil-...-clarinets and came across the remarks about wood toxicity. Here is an on-line source of info: http://www.wood-database.com/wood-articl...-toxicity/ This probably came from the table printed a couple of decades ago in American Woodturner: http://www.cs.rochester.edu/u/roche/rec....wood.toxic Here's what the British government has to say about it:http://www.hse.gov.uk/pubns/wis30.pdf
Wax (MinWax, specifically) is wonderful stuff. Yes, it will interfere with glue joints, which is why I apply it during dry-fitting to the zone around my joints. Then, it's disassembly, glue application, re-assembly, and clamping. The excess glue will easily chip off once it's dry.
"What about using wax for temporarily fixing cracks?" Mineral spirits and clean rags will get rid of that, preparing the wood for final finishing.
For an emergency repair, wax could be used, or plasticine modeling clay (the kind that doesn't harden, not Fimo-type) with success.
Best wishes. I would be glad for pictures....
Another banding method is graphite banding using epoxy, or using carbon fibre thread. I would appreciate repair techs out there telling us how this is done and commenting on the success of using Superglue.
Threads at woodwind.org: