Chemical wood burning

Make: Projects has posted an interesting way to burn designs into wood. Instead of doing the traditional method of using a hot iron to hand draw or trace patterns on the wood, they show us how to use a chemical process to make things easier. They are using a solution of Ammonium Chloride, applied with a foam stamp, then heated. When it is heated it breaks down to ammonia gas and hydrochloric acid, burning the surface. The advantage here is that you can easily use a stamp to create patterns whereas doing it by hand might be difficult.  They do point out that improvements could be made, such as adding something to keep it from soaking into the wood and blurring the edges.

Comments

  1. Oren Beck says:

    Pity it’s unlikely that most inkjet carts would not survive the caustic. Printing photos for “burning” would be way cool.. Hmn,,videojet style or similar, air over fluid tank type sprays and an ammonia rated solenoid valve might work.

    So many worthy Hack enhancements, so little time.

  2. Snowcamo says:

    Ammonium chloride is NOT caustic or dangerous in any real way. It is the ‘salt’ that gives ‘salty licorice’ or ‘salmiak’ its kick. Very popular in Netherlands and in the Scandinavian countries. Usual concentration in candy is 2 – 10 %. Sometimes additionally used pure as a thin coating. It definitely is an acquired taste.

    When heated it reversibly dissociates into hydrogen chloride and ammonia, both of which contribute to the charring reactions in the hack above.

  3. crizo says:

    I wonder if lemon juice would have a similar effect.

  4. Brad says:

    @crizo – The burning is an effect of the hydrochloric acid left behind once the ammonia evaporates. I don’t think the lemon juice would be a strong enough acid to achieve the desired results.

  5. jef says:

    Ammonium chloride is a salt and is not that caustic. If I had time, I would give it a try and put the solution in a printer cartridge. Anyone? I expect more problems from the crystallization of the concentrated solution.

  6. Mayor Defacto says:

    this is a very in ingenious idea i like it

  7. DeadlyDad says:

    BTW, NH4Cl is *cheap*. You can get an entire *kilo* of it for less than $70! I’m not sure how much 150ml (for 1l of solution) would weigh, but buying even a *tenth* of that would last you a *long* time.

    Anyone want to start a pool over when the first DTW (Direct To Wood) printer shows up here? I’d add a CandyFab-type precision heater that follows the print head, to start the reaction before the liquid has a chance to soak in.

  8. password says:

    so i guess i could just use pure HcL?

  9. Bert says:

    As NH4Cl is highly soluble (372 g/L (20 °C)) in water, I do not expect great problems with printing.

    DeadlyDad, you mention 1kg for 70 bucks? In Poland, one can buy 900g for less than 5 euros (according to eBay).

  10. yetihehe says:

    @snowcamo – There is even a page for those who would like to know what it’s like to try some salmiakki: http://www.salmiyuck.com/..

  11. K!P says:

    for those who want to use it n a printer followed by a heat source, would it not be easier to just use a laser instead. if you are going the high tech way anyway.

    this is great for using stamps tho :)

  12. DeadlyDad says:

    @Bert: Wow! When you are right, you are right: 10lb of 99% for $15!

    @K!P: While it is true that using a laser might be better, it would also be a *LOT* more expensive than droplets of solution.

    Hmmm… What about using a line laser like this one ( http://www.dealextreme.com/p/36359?r=44625746 ) to heat the solution?

  13. Wilco says:

    Today I silkscreened with bleeds and with citron acid and both works the same way.

  14. DeadlyDad says:

    @Wilco: That looks great! Would you be willing to do an instructable on it?

  15. DeadlyDad says:

    I just had a brainstorm! You don’t *need* 2000dpi precision to print the solution with, so just grab the head off of an old 24-pin dot matrix printer; the ribbon will hang onto the solution just fine.

  16. Wilco says:

    @DeadlyDad
    Maybe I will try that some time but it is basically the same process as the Sean Michael Ragan’s instructions. Only I use silkscreen to print on wood, because I don’t have Ammonium Chloride I try other substances .

    On one I use citric acid (because @cries suggest lemon juice) And mix the citric acid with water and bread flour to thicken it.

    Fore the other one I use thick bleach (brand-name Glorix) because from previous experiments I found out if you heat the bleach it will work faster.

    I also use a heat gun to apply the heat.

  17. Melissa says:

    I just got done making some garden signs thanks to all of your comments, and they turned out so great! I used a mixture of 100 mL water, 2 T flour, and 1 T citric acid. I poured the mixture into a shallow dish and put and piece of felt over the top of it to absorb the liquid and make somewhat of a stamp pad. Then I blotted my stamps on the felt and pressed them onto my wood. After I had the entire word stamped, I took them to my oven and let them cook under the broiler for 2 minutes. I’m really loving the results. Thanks, guys! :)

  18. Melissa says:

  19. Vicki says:

    I am wanting to monogram wood gifts using this technique. Do you know if this will work on bamboo? Does it need a sealer? Is it food safe? Thanks

    • Melissa says:

      I just did mine on 1×4’s from the lumber store, but I’m sure bamboo would work just fine. You would not want to do it in under your oven’s broiler if there is any curve to the wood. Definitely use a heat gun. It does not need a sealer, and since it is only flour, water, and citric acid, it is food safe. You might want to have an extra to play with and get your proportions right. I had to play around with mine a bit and it took a few pieces of wood to get it just how I wanted it.
      Another note: After all summer in the sun, the garden signs that I made bleached out a little. If I ever do this method again, I am going to do them darker than I want them to be in the end.

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