One Fix for the Red Glue Problem

JD800 by Marcos Carrera from Taiwan.

This was posted by Shupac800 at the JD-800 Tech Group:



My Fix for the Red Glue Problem

Posted By: shupac800  Sat Aug 4, 2012 8:10 pm 

I posted this tutorial to Gearslutz.com last year and thought it might be
helpful to republish it here.
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There are two kinds of JD-800 owners: those who have already experienced the
red glue of death, and those who are going to...
As we all know, the red glue that holds the key weights to the keys did not prove to be stable over a period of decades. When it gets old, and especially if the synth is kept someplace warm, the red glue softens and seeps out, making a God-awful mess.
The best way to fix this problem is to remove all the red glue, under the mildest conditions possible (NOT boiling water, as some have tried), and re-glue the weights into the keys. The keybed comes out better than new. Here's my technique.
Sodium hydroxide (NaOH, lye) solution works great to dissolve the red glue without harming the plastic. It is caustic, so WEAR SAFETY GOGGLES. Even dilute NaOH can permanently damage your eyes, and it's very likely your lye solution will be splashing about. If you get any of the solution on yourself, wash it off promptly with a lot of water.
The sodium hydroxide I like to use is granular NaOH, which I've bought on eBay. If you can get Red Devil lye or some other pelletized NaOH at your hardware store, that will work too, but the granular NaOH dissolves faster.
In a plastic bucket, mix 80 grams NaOH with 2 liters of water until all the NaOH is dissolved. (The bucket will get warm.) For you chemistry types, this recipe makes a 1-molar (1 mole/L) solution of sodium hydroxide.
Immerse the keys in the lye solution. You only need to soak the part with the glue on it, so don't worry if keys aren't completely bathed in the solution.
Leave the keys soaking in the solution for 18-24 hours. After this time, no traces of the red glue should remain, and the weights will simply fall out of the keys into the bucket.
Carefully pour the NaOH solution down the drain. Don't let the weights get poured down the drain too.
Rinse everything with a lot of water. Dry the weights as best you can. It's normal for a bit of rust-colored oxidation to form on them; don't worry about it.
At this point I soak the keys for another 24 hours in a bucket of soapy water. This bath helps eliminate the fishy odor left on the plastic by the reaction of the lye solution with the red glue.
When everything is dry and clean, re-glue the weights into the keys. I have had great results using a popsicle stick to apply a dab of 5-minute epoxy to each key. Make sure the weights are properly centered.
To remove any red goop that has seeped onto your chassis, I have found the best method is to blast the goo with freeze spray (available from Radio Shack or Fry's). Then, while the stuff is frozen hard and brittle, chip it off with a single-edged razor blade.
And that's it. Have fun.

Another fix by Daniel Forro at the same forum: 
(observe his comments about how reglue the key's weights)

My problems with red glue started few years ago after my moving from middle Europe to Japan - I think also because of high temperatures in the summer.

It's necessary to disassemble the instrument and keyboard, and leave the keys soaked in solution with NaOH (natrium hydroxide). I used a liquid for
cleaning sanitary pipes with 2% of NaOH, it's enough, but it was necessary to leave keys in it for about 2 or three days. I have used transparent plastic
cover from 50 pieces CD or DVD box, lot of keys can be inside in the same time soaked (and after finishing the job and washing box in water it can be
again used). Red glue is dissolved with it perfectly, dissappears, and metal weights still keep glued (mostly, just few fell out).

Then I cleaned the keys with water, and with isopropylalcohol from the rest of dissolved glue film and all dirtiness, and put standard universal common
liquid "white glue" (which changes color to transparent after drying, and is soluble and washable with water - I'm sure it can be purchased everywhere in the
world under different names) to fill and cover all holes around the weight, and weight itself - to avoid any possible future leakage of red glue which is
still under the weight. After drying this glue I had apply more of it on some spots where some air bubble made again holes. In the end I got perfect plastic cover
of metal weight. If I remember well, for black keys it was necessary to use more glue.

There's no problem since the repair.

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Here is another topic about the Red Glue problem: Sorting Out Flats JD800 Sticky Key - Red Glue

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Great news! JD-800 flex circuit replacement!

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