 The Clarinet BBoard
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Author: prokofiev
Date: 2004-03-20 22:27
Hi all,
Just wondering if anyone has considered using silicone (bathroom sealer)as a "glue" when repadding an instrument. I haven't tried it but thought it may have some merit. I would be interested to know what others think.
Regards
Greg
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Author: Henry
Date: 2004-03-20 22:36
I may be wrong but I think the main negative of an adhesive like silicone is that: once it sets, it can not be "liquified" again by heating, which is necessary for "floating" the pads for optimum seating. That's why shellac still is the preferred adhesive. But I'm sure other more qualified people, such as Gordon (NZ), will jump in to make this, or other, pertinent points.
Henry
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Author: Synonymous Botch
Date: 2004-03-21 01:43
Silicone adhesives retain some resilience when cured; that's an asset when dealing with movement between dissimilar materials in bathrooms - a squeak factory in the making when dealing with pads.
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Author: sfalexi
Date: 2004-03-21 01:48
Quote:
Silicone adhesives retain some resilience when cured; that's an asset when dealing with movement between dissimilar materials in bathrooms - a squeak factory in the making when dealing with pads. Well, wouldn't that rather ensure a proper seal? I mean, if the pad was for some reason misaligned, and there was a slight flexibility (it'd probably be VERY slight due to the amount of silicone that would be used) it seems to me that the pressure normally used to close a pad would be enough to ensure a perfect seal. Yes the pad would move ever so slightly, but I would think that would be beneficial to making sure that the entire tonehole was covered rather than a non-flexible, less forgiving pad.
I'm thinking about this because sometimes people use leather pads or other pads that are known to be more 'forgiving' and to me this would make silicone a 'forgiving' adhesive.
Alexi
US Army Japan Band
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Author: Gordon (NZ)
Date: 2004-03-21 10:28
1. It is very messy stuff to use. How do you deal with some that oozes out from behind the pad during installation?
2. There are various types. At least some are quite corrosive to copper alloys. I understand that the "neutral-cure" types are safe in this respect.
3. Technicians, and presumably DIYs, want to know when the glue has set. With a hot-melt glue you know it has set when the key is cool. The silicones depend on evaporation, which in this location could take hours or even days. With sprung-closed keys, they could continue oozing glue during this time.
4. One wants the adhesive to set as soon as possible, because it is only after it has set, that one can test for leaks and analyse what should be done in each case.
5. As has been said, no adjustments can be made to the pad alignment AFTER the glue has set. It is not uncommon for adjustments to pad alignment to be needed at a later date after the larger pads have bedded in more with use, because they tend to bed in deeper on the non-pivot side of the key cup, developing leaks here. Also, a technician will want to press firmly on a key, particularly a larger one, to hasten this 'bedding-in' process. This cannot be done until the glue has set.
4. Many (all?) give off ammonia as they set. One would have to know whether this has any adverse affect on timber, silver plating, nickel plating, or even behaving as an electrolyte to enable galvanic corrosion to occur in the microscopic pits in the plating, between the plating and the base metal.
5. It is particularly difficult glue to remove from a surface. What a pain for the NEXT repadding job, to have little chunks of it tenaciously adhering to the key cup.
6. As mentioned, it sets not particularly rigid. If a pad is installed so poorly that 'give' is needed behind the pad, for the pad to seal, then a new technician is definitely needed!
And that is just off the top of my head. Shellac-based adhessive/fillers have got so much going for them that they have been the mainstay for many decades. High temp glue-gun glue has some advantages, and the odd disadvantage.
IMHO, silicone has not got a lot going for it!
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Author: BobD
Date: 2004-03-21 13:13
I have tried silicone and, as Gordon says, it has several disadvantages. Assuming you have not put too much on the pad or cup, the one advantage...to me....is that the pad tends to "self adjust" due to the slow cure time. This may be beneficial in some instances....but I tend to agree with Gordon's overall analysis.
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Author: Henry
Date: 2004-03-21 15:20
Gordon gives a comprehensive list of reasons why not to use silicones for pads. Just one minor correction. All the silicone adhesives I have worked with release ACETIC ACID (not ammonia). Of course, that doesn't change his suggestion that these vapors may have deleterious corrosive effects on the metal parts.
Henry
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Author: saxlite
Date: 2004-03-21 20:02
Bobd: If you desire the "slow setting" style of gluing, then I suggest a shellac based product, such as Micro Cork and Pad Cement. When the alcohol based solvent has evaporated, you have the essentially a shellac adhesive that can be worked with the usual heating techniques if neccessary. Forty years ago, as a desparately poor college student, I repadded my sax this way- and it worked out well. Now, I use stick-shellac, just as Gordon suggests-much quicker and more secure.
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Author: ron b
Date: 2004-03-21 23:24
My response is going to be somewhat long as well as repetitive of those above. I submit it with the hope that it will EMPHASIZE the hazards of using unconventional methods without careful thought and some easily obtainable free advice. Ask any qualified local band instrument repair technician(s) this question and see what kind(s) of answer(s) you'll get. Be prepared to plug your ears when the air begins turning blue 
I've seen first hand what happens in the long run, Prokofiev, and it isn't pretty ![[frown]](http://test.woodwind.org/clarinet/BBoard/smileys/smilie2.gif)
The idea of using silicon cement is not a new one. Several years ago the INTERIM TECH at a local state university repair shop in my hometown decided to use Tub-n-Tile cement for clarinet pads. I'm sure he thought it was a brilliant inspiration at the time. The horns were student instruments from local city schools. And, I suppose, he may have reasoned that since he's just filling in anyway... no big deal. Use silicon stuff - it's pretty slow setting allowing the pads to more or less adjust themselve before it firms up. You might as well make things easy for yourself, right? Sure. Seemed like a grand idea so, with no supervisor around to offer an opinion one way or another, dozens of clarinets were repadded using silicon caulk.
The problems began to manifest themselves after the new, PERMANENT tech filled the position the next year. As those clarinets began coming back during the next two, three, four years for repairs, pads that weren't seating quite right (or possibly had shifted during the 'curing' process... who knows?), but still had some life in them, could not be repositioned - the glue wouldn't respond to the normal heating and shifting procedure. They were by then set solid and had to be pried out and replaced... after much tedious disassembly of the instrument, gouging and scraping to remove all of the, by now old and very tenacious, caulking.
All of the problems Gordon lists - and then some - were now being dealt with by the new (and highly qualified) repair technician. I think there were some instances of corrosion problems as well. I needn't go any further... but, yes, I might add, the air in that shop did turn blue at times....
Silicon adhesive is not a good thing to use for anything on woodwind musical instruments.
- r![[cool]](http://test.woodwind.org/clarinet/BBoard/smileys/cool.gif) n b -
Post Edited (2004-03-22 07:10)
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Author: Mark Pinner
Date: 2004-03-22 06:51
Why not just use pad wax? It has been working for centuries! It is cheap, easy to use and easy to clean up. It also comes out of the pad cup when re-padding. Silicone has its uses but for the most part is messy smelly (salt and vinegar) sh*t. Why would you put it, or hot melt glue for that matter, near a musical instrument. Shellac is wonderful for sax pads which explains why it has been used for so long.
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Author: ron b
Date: 2004-03-22 08:07
It seems quite understandable to me why someone would use silicon caulk, Mark.
Pad cement sets up rather quickly, as Gordon points out. Caulk on the other hand is relatively slow setting, looks nice and is waterproof when set. It can be cleaned up with water if you do so before it sets - a long time compared to heated shellac based adhesives. Shellac has to be scraped, chipped or melted away with alcohol after it has cooled for about a minute. The reasoning is that the slower setting caulk affords much more working time to get the pad leveled correctly before it cures.
Also, shellac heated to a proper consistency during pad installation is ordinarily very stable. But shellac can, and often does, fail to hold when subjected to a very cold environment; the slightest bump can cause a pad to drop right out. There are a lot of variables with shellac, if not done "just so". Caulk is much less fussy in that respect. So, at first glance caulk would appear to be the ideal solution compared to the drawbacks of shellac.
However, in field-tested service the results of caulk are not at all nice. In my opinion, and from what I've seen first hand, hot melt glue (given no other option) would be my distinct preference any day. Learn to do it right and everyone'll be happy to know you. Do it wrong and the air'll be blue long after you've moved on.
- ron b -
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Author: Gordon (NZ)
Date: 2004-03-22 10:40
Henry, thanks for correcting me. Acetic acid, not amonia. I just got my acrid smells mixed up.
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Author: BobD
Date: 2004-03-22 13:40
Ah, that good old aroma of HAc....But, Hey, what the heck is pad wax, Mark.
Saxlite: Yes, I use both Micro and stick shellac. I must admit that I have yet to master the heat gun. When necessary for reseating I just use a soldering iron carefully.
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Author: David Spiegelthal ★2017
Date: 2004-03-22 14:25
Anyone who has a clarinet or sax I've repadded has silicone glue holding the pads in. I won't go through the rationale for using it --- it's been discussed at length both here and on the SaxOnTheWeb forum and I'm not interested in another battle on the subject.
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