A small bakelite chip can really be an eyesore. Here is a simple method for repairing such damage. Please beware that this method is not reversable. You’ll have to grind away the material applied to the bakelite if you are not happy with the result, in effect making the damage greater. So be very sure that you really want to do this.
Think before you act: do you really want to repair it?
Please consider whether you really want to repair that chip. After all a telephone made of bakelite is decades old and has often seen the better part of a century. So wear and tear is to be expected for an object that has seen daily use for decades. It ads to the character of the telephone and is part of its history.
What are we going to do?
We are going to apply epoxy resin to fill in the missing chip. The patient in this case is a Standard type 1954 wall phone, with a small chip from the top right corner.
The resin will be cast in such a way, that it forms one piece with the bakelite and follows its original shape exactly. Before casting we are going to color the resin to match the bakelite.
In this case we have black bakelite. Colored bakelite and white bakelite is far more difficult. It will need to take a lot of testing beforehand to get the color right.
What do we need?
- epoxy resin, in the form of 2 component glue
- a piece of paper to mix the glue and the color
- coloring powder, in this case Norit, ground to a fine powder
- clear tape. Do not use the cheap thin tape, but the strong thicker kind
Step 1, clean and polish
Before we can start applying the resin the bakelite needs to be washed. If there is dirt on it, the resin will adhere to the dirt and not the bakelite thus forming a weak bond. I wash the bakelite in warm water with washing up liquid.
I brushed the edges where the chip is missing thouroughly with a brush. Please mind that in the example here, it was an old chip. So there was dirt on the surface where the chip broke away.
Also polish the bakelite before repairing it. Polishing afterwards may damage the resin cast, because it needs time (days!) to harden. Also you can match the color of the resin better if the telephone is polished.
After polishing, clean the fracture surface again.
Step 2, making the mold
I use tape to keep the liquid resin in place until it has hardened. With tape you can follow the shape of the bakelite exactly. Even simple curved surfaces can be repaired in this way. More complex curves cannot be repaired in this manner.
Please make sure there are no folds, creases or fingerprints on the tape, where the chip is missing. These will make an imprint in the resin.
I test fit the tape carefully, and peal it away partly before applying the resin.
Step 3, mix the resin with the color
As I am repairing black bakelite, I use Norit tablets. They are made of activated charcoal. I grind them to a fine powder using a pestle and mortar. If the bakelite is stil nicely black and shiny this will make a good color match. If the bakelite is somewhat faded, you’ll need to mix in some grey.
For colored bakelite you may want to try out coloring little bits of resin first to get a good colormatch, before you do the actual repair.
A ratio of about 1 part Norit powder to 10 parts resin is enough to color it black.
Step 4 apply the resin
When applying the resin you have to work quickly, otherwise the resin becomes too thick. You have about 20 min, which is quite enough time.
Please mind that the tape is peeled back, before applying the resin.
With a toothpick I cover the edges in a good layer of resin. Make sure the resin is right up to the edge, covering the total fracture surface.
Then put the tape back over the bakelite. Make sure the tape is straight. Be carefull, if you put the tape on it may warp. You’ll end up with a wavy surface of the repair. So double check that it is straight and even. You can use the reflection of a lamp on the tape to check this.
Then, with a toothpick, apply more resin, working your way from the resin you already applied up to the edge of the bakelite.
Rub the toothpick over the inner surface of the tape, where it is covered with the liquid resin. This will remove air bubbles from the surface.
When you have applied the resin, leave the telephone to rest. You may need to support your telephone in a certain angly to make sure the resin does not run off.
Step 5 waiting and removing excess resin
Then wait at least 24 hrs before removing the tape.
After that you will need to remove the excess resin and smooth down the edge. Please make sure the resin is hard enough, otherwise it will warp and deform.
And voila: hard to tell there was ever a chip, don’t you think?
See also this article on how to repair cracks in bakelite: