Hot Hide Glue for Pneumatics
By Craig Brougher
Here's some more tips that make using hide glue handy:
1. Use only natural bristle brushes, preferably China bristles because they will not distort from sitting a long time on the bottom of your pot or jar, but they flow out the glue evenly and give you control.
2. Use a brush that carries lots of glue at once. Hide glue sets by temperature, and you must also practice applying it quickly and evenly, keeping the applied glue warm until the parts are joined, and then positioning it quickly, else you will have a "cold glue joint." Hot hide glue is exactly like solder in that respect. It sometimes looks good when it isn't.
3. First pre-size the stack shelves upon which you mount your pneumatics with thinned down hide glue. You can go ahead and plant them any time. You don't have to wait for it to fully dry, although letting it set up first is necessary. This way, the bond is better although excessive alignment time will still ruin it.
4. Working out of a heated glue pot is easier by adding the smooth styrofoam pellets or "peanuts" to the glue. (_Don't_ get the biodegradable kind). They float on top, supporting the brush, sealing the top of the glue and preventing evaporation almost perfectly.
5. Good glue crystals are not necessarily blonde, by the way. The color depends partly on the amount of rendering but mainly on which proteins were retained. Stronger proteins are darker proteins, so blonde glue is closer to edible gelatin and uses light proteins only. For example, the glue sold today by Player Piano Co is probably better than what they used to buy, if it is the same glue that I tested for them and also use myself.
6. Good glue settles in the pot. Stirring hot glue brings the heavier proteins back up, and makes for stronger glue (specific gravity), but some glues today aren't even strong enough for player work and have such terrible characteristics (like overly thin viscosity) that they are practically unusable, and an accident waiting for a place to happen. Don't use lousy hide glue or you'll be sorry! See my previous contributions to this subject.
7. Smelly glue is caused mainly by leaving hot glue open too long. The mold spores aren't mainly in the glue but in the air (ask anyone who has made their own bread yeast). So also is a host of bacteria which get really active at about 150 degrees F. (Some bacteria aren't destroyed even at very elevated temperatures, like over 300 degrees F, so don't think the heat takes care of all bacteria). It feeds on what fat is left in the glue, and it's this characteristic that causes glue to stink, not mold spores. That's why glue kept in bottles doesn't get smelly as quickly. Mold will only grow on room temperature glue.
8. If you use glass jars like pickle jars, a small yogurt cup lid or a tennis ball can lid is just about perfect to keep the jar covered when not in use.
9. Adding water will slow down the drying time, but weakens the bond. Vary the viscosity for the purpose. Use medium for pneumatics, thick for heavy felt and gasket leather, double glue all heavy bellows covers, and then iron them down in addition when mostly dry. Use thin glue for covering pneumatics, and very thin glue for replacing pouches. When you make new pneumatics, always size the end grain of the leaves before you cover them. Finally, use a medium thin viscosity glue for "motor cloth" bellows having a light double cloth cover.
10. Test everything after it is dry. Test pneumatics by blowing (not sucking) into them. I use 25 inches air pressure with a cork over my air gun. If the cover pops, fix it again. Then test it again. When you don't take anything for granted, you never have to do anything over. Works every time.
Craig Brougher
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(Message sent Tue 3 Dec 1996, 15:26:49 GMT, from time zone GMT.) |
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