The Studio – Jewelry Blog by Rio Grande

The Charcoal Block: Mark Nelson’s Tips for Getting the Most from this Useful Tool

May 7, 2012

Jewelers have been soldering on charcoal blocks as a refectory material for centuries. It may be for this reason that there it's actually very difficult to find written information about it. Nearly every text I looked at had pictures of them being used but few mentioned that the blocks need to be wrapped with wire to prevent breakage and that they provide a reducing atmosphere. The best source of information I found was in Jewelry Concepts and Technology, a book by Oppi Untracht (at 840 pages it’s considered by many to be the Jeweler’s Bible). Untracht's book has a whole paragraph on charcoal blocks. Although it’s not the only type of soldering block on my bench, charcoal blocks have several benefits.

Here are some of the benefits of charcoal blocks:

  • They absorb very little heat and reflect it back, causing pieces to heat up faster.
  • They provide a reducing atmosphere (this consumes the oxygen around the piece being soldered which helps to prevent fire scale)
  • They can have pins shoved right into them.
  • Broken pieces can be re-used.
  • The surface can be re-sanded to like-new.
  • They're made of organic material. Wood, such as ash, beech, oak, walnut, elm, and a few others

    A new charcoal block and a used one, hot with glowing embers after soldering.

But they also have a few drawbacks:

  • After use the block can crack.
  • Block can keep burning after soldering.
  • They can be messy.
  • They can emit fumes from burning – be sure to use in a ventilated space.
  • They get used up

After use the block can crack and break.

Probably one of the most valuable things about the charcoal block is its versatility. Here are some ways to use and protect your block.

 There are different ways to wrap your charcoal block so it will stay together. There is no rule about how to do it. I once had a boss that used duct tape, but it smelled horrible when he would burn it.

Pieces can be positioned for soldering by pushing pins into the block.

One unique quality of the blocks is that they can be used as a mold for pouring metal. Simply carve the block and then pour the metal in, it’s a great way to make a simple casting or ingot.

Be sure to save all the coal dust. This can be placed on another non-charcoal block to provide the same reducing atmosphere benefits.

Broken pieces of the block can be saved and placed in a container for those objects that are odd-shaped and need to sit on a softer surface for support.

Be careful after soldering. The broken up pieces have embers that stay lit after soldering. I place a lid on the can after soldering to snuff them out and extend the life of the charcoal.

Rio also currently carries a hard charcoal block. This is a wonderful block option and lasts much, much longer than its softer cousin. It still provides the same reducing atmosphere properties but you won’t be able to carve it or push pins in it. I like to have both on the soldering bench; I can use the hard for most applications and then use the soft for those times when I need to push pins in or carve it for a small ingot. I hope this is helpful!

Mark Nelson

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Comments (9)
  1. Great post! I really enjoy hearing all about a specific product, it’s uses, benefits & drawbacks!

  2. Thanks for reading! I’m so glad you found the post useful and we love to have your feedback.

  3. Interesting but not for me.

  4. Does Rio sell the soldering pins pictured with the copper sheet?

  5. Hi Kim,

    Those pins are actually just handy, basic t-pins that can be found at any office supply store. I hope that’s helpful.

    Thanks for reading!

  6. Any special wire needed to wrap the block?

  7. I ave the same question as cellsworth. I would like to know what kind of wire was used in the pictures above. :-)

  8. Also, I my block broke in 1/2. That is how I found this chat while searching for an answer. Can I wire wrap it and continue to use the block broken?

  9. Hi, to address Cellsworth and Cher788’s questions.
    You can use just about any binding wire, some like iron, I like using a 26-24 gauge stainless wire, I find that it’s easier to deal with.
    If your block ends up breaking in ½ as many of mine have. You can keep on using them, just bind them and they should be good for a while longer. I hope this is of some help.

    Mark Nelson
    Rio Grande Technical Support

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