How to repair chipped bakelite

Chip, unrepaired
Chip, unrepaired

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?

Epoxy resin, pestle and mortar and Norit
Epoxy resin, pestle and mortar and Norit

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
  • toothpicks
  • a piece of paper to mix the glue and the color

    Active charcoal tablet, ground to a powder
    Active charcoal tablet, ground to a powder
  • 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

Applying the tape
Applying the tape

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

Resin and powder
Resin and powder

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.

Mixing the resin and charcoal powder
Mixing the resin and charcoal powder

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

Applying the resin
Applying 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.

Ready for more resin
Ready for more resin

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.

All the resin has been applied
All the resin has been applied

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

Tape removed
Tape removed

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:

How to repair a small crack in bakelite

Was there ever a chip missing?
Was there ever a chip missing?

9 Comments

  1. Really bravoo that’s is great because the restoration my hobby about 30 years ago and i did that i lot times with bakelite without to learn but when i saw some one do that really i am happy because some people did right thing in the world. Hope you good luck

  2. That is a beautiful fix! I collect/hoard/restore old radios and vintage electronics, and this method works perfect,I tried it on restoring a rotary knob I could not find a replacement for, and your process worked just as good in that application! It is even machinable and can be polished a bit after.

    Thanks for sharing a great tip!

  3. wauw geweldig! zo eenvoudig en met zo’n goed resultaat. Ik heb een nog functionerende telefoon, dus goed om te weten dat dit nog kan. Bedankt voor de goede en gedetaileerde uitleg!

    • Hi Donna,

      Thank you for your message. I’m sorry, I have very little time for anything besides phones. I cannot find the time to repair your tiles.

      I doubt that it would be economic to have them repaired by me anyway. Nor would the repair withstand actually playing with these tiles.

      Groeten,

      Arwin

  4. I have a brown bakelite radio which had a large piece broken. I glued that in place (using very runny cyanoacrylate glue and corn starch, a trick I learned from joining Corian. The corn starch acts both as structural filler and provides capillary action to draw the glue in).

    Now that it is set, I am wondering how I may hide the crack line and fill in the few missing chipped bits. I thought perhaps I should cut a piece of Bakelite from an invisible part, grind it to a very fine powder, sprinkle and pack it tight into the crack line then whisk in some cyanoacrylate. Once it sets, I will sand it smooth.

    How do you gage my chances of success?

    • Hi Alain, mixing bakelite powder with glue, to match the colour is a method I have heared about. I do not have much experience with it myself, certainly not with colours other than black.
      I would try a drop with powder on the inside, to see if the colour really matches. If it does, it should be possible to make the crack and chips disappear.
      Regards,
      Arwin

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