List - As I've read through the posts concerning methods to glue keytops, I've been concerned about the misinformation concerning the use of contact cement. I am not an authority on the use of either PCV-E glue, or Mike's European glue, but I do have concerns about their relatively weak bond. If, as Debbie L.'s testing seems to bear out, keytops glued with either of these adhesives may be removed with "easy" to "moderate" effort with a flat bladed knife, how much effort would it take on the part of a determined 4 or 5 year old to removed said keys? I would very hesitant to put a set of keytops into a piano in a home with small children with no more assurance than that. Kids, being the inquisitive creatures that they are, at some point will try pushing up on the overhang of the naturals when no one is watching. God forbid one should pop off, because if it does then the "Hey Suzie, look what I can do!" phenomenon sets in. The classic case for me was the customer with a set of twin 4 year old boys, who discovered what they were able to do when left unattended for 15 minutes by their babysitter who was texting her boyfriend and watching a movie in the adjacent room. After one key had been popped off, 51 more followed. When finished, the two boys craftily returned every keytop to the correct key, and neatly straightened them out, so that to the casual observer, nothing had been touched. The kicker was, when the mother discovered what had been done the next day when she sat down to play the piano, the boys claimed that the "babysitter must have done it!" These keys, by the way, had been replaced several years by another technician before I was hired as her tuner. I'm not sure what adhesive had been used, but it obviously didn't do the job. Anyway, I just would like to set the record straight as concerns the use of contact cement (for molded keytops with fronts). What I like about contact cement is that used correctly, there will never be this type of failure. Plus, it requires the use of no clamps - just a 30 second squeeze in a cork-faced vise will do the trick. Let me therefore take some of the comments made, and respond to them. (I have, in the past, tried contact cement but I hate the vapors. Debbie L.)* -* A fair observation, but one that is not difficult to deal with. Unless you're working in an area the size of a broom closet, the vapors may be dealt with by providing a bit of cross ventilation. A fan, placed off to the side so that a gently breeze blows across the work area, will do the trick. The vapors are not nearly so intense as CA glue. The vapor given off by polyurethane affects me more than that of contact cement. (Some seem to have no problem with it, but I've seen enough failures to not want to find out why first hand. Ron N) - Two reasons come to mind Ron. Number one, the top of the keystick must be coated twice. The first coat will largely soak into the wood. The second coat, applied at least 15 minutes later, will provide the bond. If only one coat is applied to the wood, the bond will not be strong enough to prevent failure down the road. Number two, if too much time elapses between coating the surfaces and bonding them together (refer to the bottle, but something along the lines of 2 or more hours) the bond strength will not be strong, if the surfaces indeed bond at all. (Contact cement works well but it's toxic, and since there are other good options it seems best not to use it. David Weiss) If by toxic you mean you wouldn't want to drink it, you're probably right. However, if I'm not mistaken, I believe there are a lot of things used in the shop which would fall into that category. Lacquer thinner, CLP, mineral spirits, etc., come to mind. Come to think of it, I don't believe that I would want to pour myself a glass of PCV-E to chug either, although it does look temptingly like a milkshake! (I don't care to use contact cement as I find the failure rate high and the glue itself can mar the surface of the keytop if it gets on there. David Love) Again, as I commented to Ron, if you simply coat the keystick once, it will not provide adequate adhesion. As to the fact that contact cement will mar the surface, that is exactly the reason it works so well when applied correctly. The cement reacts chemically to the plastic keytop, and bonds with it in a way that PCV-E glue will not. The reason PCV-E wipes off so easily, is because it does not interact with the plastic. That is also the reason keytops thus applied may be removed with "easy to moderate" effort. This can be a pain, I'll admit, for the first-time user who doesn't know how to correctly apply contact cement. With correct procedures, however, you will not get the cement on either the tops of the keys, or your fingers. (Or in the case of contact cement, apply pressure to the top and front at the same time. There is currently no clamping system available to do this (that I know of) and I don't believe the old Oslund system addresses this issue either because one of our clamping systems is an Oslund clamping setup and I don't see it as an option. Mike Morvan) One of my points about using contact cement is that clamping is unnecessary. Once the keytop with the front is put in place (again, methodology is everything), the front is secured in place with a downward pressure of the key on the edge of the bench. The top is secured by placing the key momentarily (while the next assembly is being made) into the cork faced vise. After this brief pressure is applied, no further clamping is needed. (Also, it is far too strong a joint making future removal for repairs/replacement a nightmare. Debbie L.) Debbie was speaking here of an acetone based adhesive at this point, but I've heard others express this concern as regards to contact cement as well. Removal of keys bonded with contact cement is done with the application of heat via a flat iron. A lightly dampend cloth (to prevent the iron from adhering to the plastic) is placed in between the iron and the keytop, and heat is applied for 10-15 seconds. After heating the keytop will peel off with a small putty knife. Occasionally, while working on a set, I'll drop one and chip the corner, or in filing I'll chip off a bit too much at the notch, so I have a extra set of keys for just such an occasion. Again, as I stated before, whatever works for you is what's best. I just hated to see people not try a method because of misinformed opinions. In that I've used contact cement successfully for 35 years, I know that it does work. Chuck Behm ** ** -------------- next part -------------- An HTML attachment was scrubbed... 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