Carboxymethyl Cellulose or Sodium Carboxymethyl Cellulose (its sodium salt) is a cellulose gum used in some bubble solutions. It is often called CMC. It usually is packaged as a white powder.
In some countries (not the U.S., however), it is the primary or sole ingredient of wallpaper paste. So, recipes that call for wallpaper paste are usually making use of CMC.
It has been reported that it is an ingredient in some commercial bubble solutions.
It is related to HEC and HPMC (also cellulose gums), but the characteristics that it brings to bubble juice are distinct from what HEC and HPMC, which are distinct from each other, bring.
Sept. 2013. These are my impressions as of Sept. 2013.
I have not been impressed by CMC as a sole polymer. There is much room for exploration, however. While there are anecdotal reports of this polymer being very effective, I have been disappointed by it as a primary or secondary polymer -- although I have a nice three polymer mix (see PHC, below) with which I have created supergiant bubbles.
It was reported to me (by someone that did not supply a suggested recipe) that high-viscosity CMC was the most effective polymer other than PEO for creating bubble juice. With high expectations, I explored it for a while (though those explorations have not made it onto my blog because I felt they were too cursory). I did not find it anywhere near as friendly as HEC, and I gave up trying to use it.
I find that as a sole polymer, CMC-based mixes create stiff bubbles that are not very self-healing. They seem brittle (for lack of a better word) and are easily broken by the wind. However, it does seem effective in some multi-polymer mixes.
I sometimes use CMC along with PEO and HPMC or HEC. On SBF, the Soap Bubble Fanciers Yahoo Group, there are reports of a synergistic relationship with HPMC which results in a PEO/CMC/HPMC mix having unique benefits not seen with a combination of any two of those polymers. I have had some very nice sessions with a mix that I call PHC (PEO/HPMC/CMC) and also what I call PHeC (PEO/HEC/CMC).
I am not sure if the PHC mixes were better than a well-tuned PEO-only mix or HEC-only mix; however, I did have some great sessions with it (see the article and related pictures and video). I suspect that CMC's benefit in this mix is to improve the 'feel' of the mix and its flow off the strings.
Hydration and SolubilityEdit
The application notes for Aqualon indicates that room temperature water is fine. High-shear mixing is recommended for full viscosity development -- unlike PEO for which high-shear mixing is problematic. CMC is highly shear-thinning in concentrated solutions. So, Aqualon recommends that the water be moving vigorously when the CMC is added in order to minimize viscosity build-up.
They recommend 4 types of dispersion for obtaining lump-free solutions.
- Add the CMC to a vigorously (machine) stirred water. They say "the addition must be slow enough to permit the particles to separate .... but it should be fast enough to minimize viscosity buildup".
- Slurry with a water-miscible liquid (in which CMC is not soluble) such as dry alcohol, glycol or glycerol.
- Mix the CMC with a non-polymer such that the CMC is less than 20% of the powdered material.
- Use of a water eductor.
See the wikipedia page: Carboxymethyl Cellulose
Articles in the CMC-polymer category.
The SBF discussion that inspired PHC is here .