Hello, David,
Since I don't see it mentioned elsewhere; and, in a previous lifetime
wound up servicing a number of Zimmerman instruments (I think that it
was Bernie Comsky who was the importer in LA), I'm chiming in long
enough to suggest that, before doing much gluing, that you check the
keys carefully to see how much, if any, measurable/noticeable shrinkage
along the length of the key has occurred over the years.
Note that I'm not necessarily suggesting/insisting on a deeply reductive
analysis here. (Unless you have access to factory manufacturing
specifications, you can't.) Rather, a careful examination and
measurement of several keys per section to see if there is any
noticeable difference in length of the head, tail, overall length,
distance from front to balance, balance to capstan...that kind of thing.
Many lower-end Eastern European instruments from that period had
poorly cured and overly-kilned wood from which questionable keysticks
were cut.
If there isn't a noticeable amount of variation in the sticks, you're
probably OK with any of the suggestions previously made. If, however,
things are looking flaky, key-wise, and the owner doesn't have the money
or doesn't want to spend it, you've got a series of choices/decisions to
make as to how to proceed.
YMMV.
Kind regards.
Horace
On 11/30/2017 11:50 AM, Susan Kline via Piano Technicians Guild wrote:
> Please do not forward this message due to Auto Login.
>
> For something like this, I'd use the glue trick. You can find my article about it in the October 1997 Journal.
>
> The basic protocol is to mix CA and white glue. The white glue acts as a mild and non-toxic "kicker" for the CA, which sets up in a few seconds.
>
> If the keytops were ivory, I'd put a thin even smear of white glue on the key stick, then put dots of water-thin CA on the back of the key top, not smearing it around but being sure that there are some near the corners. Gingerly pick it up and turn it over, since any CA on the ivory will need to be removed with acetone. Press down carefully with really clean dry hands to make sure it's the right place, and it should be stuck in a very short time. The reason for using the white glue on the key stick is because water warps ivory. Wipe away the squeeze out, once again being sure none of it gets on top.
>
> For plastic you could probably do it either way -- a thin smear of white glue on the back of the key top, dots of CA glue on the key stick, with attention to the corners, carefully put it in place and press, being especially careful not to let any CA get onto the top, because the acetone in it makes it etch the key top, and you will not get it back off. I think I'd leave that little brown residue from the previous (failed) adhesive. It probably would accept the glue better than bare plastic.
>
> I used to put the dots of CA on the ivory and then quickly spread it out with a small screwdriver to make a thin even sheet of it. I found that it often sets up too quickly this way, and some of the ivories would come back off. The dots give you a few seconds more time, since the CA in the middle of them isn't exposed to atmospheric humidity, so it stays liquid longer.
>
> I've found, looking at old but replaced plastic key tops, that contact cement often seems to warp them a little, leaving them looking lumpy. The CA-white glue never does this. You just have to pay very close attention so none of it ends up on top. Also, from experience, if your hand contacts CA while it has even a trace of white glue on it, it will get stuck to yourself or some other thing with much greater ferocity than usual. I found this out by gluing my left thumb to the middle of my index finger while putting on a rubber button one day. I actually had to go to the car and use nail polish remover to free them. Even then, it took some time and effort.
>
> It's a good idea, using CA, to have some acetone along with you, not that you should need it if you are careful.
>
> ------------------------------
> Susan Kline
> Philomath, Oregon
> ------------------------------
> -------------------------------------------
> Original Message:
> Sent: 11-30-2017 13:02
> From: David Trasoff
> Subject: Keytop repair
>
> Greetings,
> The piano is a Zimmerman, a GDR (East German) upright, probably from the 1970s-1980s. Almost half of the molded key tops have come unglued (see photos). Although replacing them might be the preferred course of action, I suspect that the cost may be more than the owner is willing to bear. What type of fast acting contact cement or glue would be suitable to reattach the key tops with a minimum (or even no) clamping time?
>
> Thanks,
> David
>
> ------------------------------
> David Trasoff
> Professional Piano Service
> Los Angeles, CA
> 323-255-7783
>
david@professionalpianoservice.com <
david@professionalpianoservice.com>
> ------------------------------
>
>
> Reply to Sender :
http://my.ptg.org/eGroups/PostReply/?GroupId=43&SenderKey=e7039941-832b-4518-bf40-68a323e0415b&MID=683226&MDATE=756%253c466485&UserKey=3feecf45-4a69-4cff-bbb2-fd6c7eaf0569&sKey=KeyRemoved>
> Reply to Discussion :
http://my.ptg.org/eGroups/PostReply/?GroupId=43&MID=683226&MDATE=756%253c466485&UserKey=3feecf45-4a69-4cff-bbb2-fd6c7eaf0569&sKey=KeyRemoved>
>
>
> You are subscribed to "Pianotech" as
hgreeley@sonic.net. To change your subscriptions, go to
http://my.ptg.org/preferences?section=Subscriptions&MDATE=756%253c466485&UserKey=3feecf45-4a69-4cff-bbb2-fd6c7eaf0569&sKey=KeyRemoved. To unsubscribe from this community discussion, go to
http://my.ptg.org/HigherLogic/eGroups/Unsubscribe.aspx?UserKey=3feecf45-4a69-4cff-bbb2-fd6c7eaf0569&sKey=KeyRemoved&GroupKey=2bb4ebe8-4dba-4640-ae67-111903beaddf.>
Original Message------
For something like this, I'd use the glue trick. You can find my article about it in the October 1997 Journal.
The basic protocol is to mix CA and white glue. The white glue acts as a mild and non-toxic "kicker" for the CA, which sets up in a few seconds.
If the keytops were ivory, I'd put a thin even smear of white glue on the key stick, then put dots of water-thin CA on the back of the key top, not smearing it around but being sure that there are some near the corners. Gingerly pick it up and turn it over, since any CA on the ivory will need to be removed with acetone. Press down carefully with really clean dry hands to make sure it's the right place, and it should be stuck in a very short time. The reason for using the white glue on the key stick is because water warps ivory. Wipe away the squeeze out, once again being sure none of it gets on top.
For plastic you could probably do it either way -- a thin smear of white glue on the back of the key top, dots of CA glue on the key stick, with attention to the corners, carefully put it in place and press, being especially careful not to let any CA get onto the top, because the acetone in it makes it etch the key top, and you will not get it back off. I think I'd leave that little brown residue from the previous (failed) adhesive. It probably would accept the glue better than bare plastic.
I used to put the dots of CA on the ivory and then quickly spread it out with a small screwdriver to make a thin even sheet of it. I found that it often sets up too quickly this way, and some of the ivories would come back off. The dots give you a few seconds more time, since the CA in the middle of them isn't exposed to atmospheric humidity, so it stays liquid longer.
I've found, looking at old but replaced plastic key tops, that contact cement often seems to warp them a little, leaving them looking lumpy. The CA-white glue never does this. You just have to pay very close attention so none of it ends up on top. Also, from experience, if your hand contacts CA while it has even a trace of white glue on it, it will get stuck to yourself or some other thing with much greater ferocity than usual. I found this out by gluing my left thumb to the middle of my index finger while putting on a rubber button one day. I actually had to go to the car and use nail polish remover to free them. Even then, it took some time and effort.
It's a good idea, using CA, to have some acetone along with you, not that you should need it if you are careful.
------------------------------
Susan Kline
Philomath, Oregon
------------------------------