Epiphone Cortez Repair Blog #3: Scrapers, glues and bagging

Hide Glue

Hide glue, sometimes called animal or pearl glue, has been used in the manufacture of instruments for hundreds of years and it is still a popular choice among builders and repairers. It can be used thick or thin and anything you’ve stuck with it can be unstuck by applying heat. The traditional instrument workshop would have a pot of glue bubbling away all day: always ready for use. For a small shop, that’s not really practical, but here’s an even more convenient system anyone can use.

Hide Glue Made Easy

Hide glue comes in small hard beads, or pearls. These need to be rehydrated before use. Here’s my method to make a small batch. Everything scales normally when using hide glue, so the method remains the same for all quantities.

 

Take a shallow container such as a tupperware box, old takeaway tub or similar. Fill it with half an inch or so of cold water. Pour that into a measuring jug.
Now a little bit of maths. Hide glue is mixed somewhere in a ratio of between 1.5 to 2 parts water to glue depending on manufacturer. I go for 1.8:1 with this glue.

This dish held 150ml of water (i.e. 150 grams).

So, 150g / 1.8 = 83g.

So, I’ll weigh out 83g (more or less) of glue, then add our water back into the container.

We’ll leave this to stand for about an hour while the pearls absorb the water.
Once the water has been absorbed, the pearls have swollen up big and fat like unappetising fish eggs. Although hide glue is non-toxic, I wouldn’t recommend eating it outside of a post-apocalypse scenario.
Next, we take it over to the stove and heat it using a bain-marie until everything is nice and smooth and there are no lumps. The key temperature in hide glue is 60°C. Stick a thermometer in the pot and get the temperature at a nice steady 60°C, then float the glue pot on top and stir it occasionally.

To keep the dish of glue from capsizing, I peg it in place. This is just one of the 367 uses for wooden pegs. Always keep them close to hand.

Now we put the container in the fridge and let it cool down completely. When it’s set, it’s like a creepy, rubbery jelly. We can then cut it into individual portions.
Each portion is just about the right size to fit comfortably in a little shot glass or sauce cup. We can throw the lot into the freezer where it’ll keep fine for years. Glue stored in the fridge will last only a few weeks before it goes funky and mouldy.
When I want to use a cube of glue, I have a secret weapon that makes it really easy. It’s a baby bottle warmer. On its highest setting, this warmer gets the water to almost exactly 60°C. That means I can easily keep the glue at working temperature.
The glue brick goes into a little cup (medicine measuring cup, shot glass, sauce cup) and gets heated up to the right temperature in the bottle warmer. It doesn’t take up much bench space and the cup is a nice convenient size to take over to the work.

That’s how you make hide glue, but using it takes time and practice. The key, as in all gluing operations, is to get everything prepared and dry run to make sure all your clamps and cauls are ready. We’ll look at a few techniques in future blog posts.

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