otto Posted December 18, 2014 Posted December 18, 2014 Just a curiosity. I've been looking for CMC sources and discovered that we actually use some in our business at some locations. On the inventory it is listed as "Sodium Carboxymethylcellulose - cell gum". A quick perusal of CMC products returns that sodium is a rather large portion of cheaper, read less refined, CMC gums, as much as 40%. Since sodium can be a bit hygroscopic I'm wondering if it makes a difference what CMC I use. Additional research uncovered that food grade CMC, which is what I would have access to, is generally more refined and has less sodium than "standard" CMC that is found in wallpaper paste for example. I wouldn't have given it a second thought and just made a deal for a couple pounds except I saw the "Sodium" in the ingredient label. Thoughts? Much appreciated....
dagabu Posted December 18, 2014 Posted December 18, 2014 Ultimately, you will have to try some in a comp and see of it imparts any coloring to the flame. The amount of sodium would be tiny in any case. I use the food grade and it works well in everything I have used it in so far.
stix Posted December 20, 2014 Posted December 20, 2014 (edited) Just a curiosity. I've been looking for CMC sources and discovered that we actually use some in our business at some locations. On the inventory it is listed as "Sodium Carboxymethylcellulose - cell gum". A quick perusal of CMC products returns that sodium is a rather large portion of cheaper, read less refined, CMC gums, as much as 40%. Since sodium can be a bit hygroscopic I'm wondering if it makes a difference what CMC I use. Additional research uncovered that food grade CMC, which is what I would have access to, is generally more refined and has less sodium than "standard" CMC that is found in wallpaper paste for example. I wouldn't have given it a second thought and just made a deal for a couple pounds except I saw the "Sodium" in the ingredient label. Thoughts? Much appreciated.... Wow otto!! this is absolutely bizarre - I was just about to post a similar thread titled: "Is sodium carboxymethyl cellulose the same as CMC?" and just happened to see yours near the top of the threads. Although my purposes for CMC use may be different than yours, hopefully we can "kill two birds with one stone". I hope you don't mind me asking other questions instead of solving yours . Ultimately, you will have to try some in a comp and see of it imparts any coloring to the flame. The amount of sodium would be tiny in any case. I use the food grade and it works well in everything I have used it in so far. Thanks for that info dagabu. That answers my question and hopefully helps otto, but my use is not for star comps (yet). I have two possible uses: 1. Using cmc + gum arabic for my black match slurry (from what I've read, more flexible than dextrin, which is what I use atm).2. Using it as one of the ingredients in glue (along with casein / waterglass / dextrin etc...) for rolling tubes. It seems what you are saying is that the amount of sodium would be unlikely to cause a major problem? What really pisses me off is just trying to get hold of some pure cmc here in Oz. The best I could do was what I bought from the biggest hardware chain in the country, at about $1 per 3 grams... What a crock of sh*t!! [EDIT] Anyway it's not as though I really NEED cmc, but I like to experiment - and almost just for it's own reward, and therefore have all the right ingredients at hand. Edited December 20, 2014 by stix
schroedinger Posted December 20, 2014 Posted December 20, 2014 (edited) Sry wrong topic pls delete Edited December 20, 2014 by schroedinger
Mumbles Posted December 20, 2014 Posted December 20, 2014 My impression is that the product we purchase as CMC is almost always sodium CMC. As in a sodium salt of CMC. Some of the less refined versions have extra sodium salts in the product no related to CMC. I too have seen this 40% value. It seems that food grade or USP grade (or equiv for other countries) would be the purest available. They'll still have sodium in it, so blackmatch and slurry priming type applications may be the best. It may not effect it much, but I don't like the idea of intentionally adding sodium to anything of color. If you're looking for an alternative for use in colored compositions, something like methylcellulose or ethylcellulose may be an option. They're not water soluble, but soluble in most common organics we use.
Jakenbake Posted December 20, 2014 Posted December 20, 2014 (edited) Mumbles I have some methyl cellulose and isn't it soluble in cold water but insoluble in hot water? It may just be that I have some really shity methyl cellulose. Edited December 20, 2014 by Jakenbake
Mumbles Posted December 20, 2014 Posted December 20, 2014 Yep, that appears to be correct. I came back to correct myself, but clearly thats too late now. I'll be honest. I was only looking up data on ethylcellulose, since that's what I had. I thought I had confirmed them quickly for methylcellulose, but that is not the case. It has some weird solubility properties actually. It forms suspensions with ethanol and dichloromethane individually, but forms a clear stable solution in a mixture of the two.
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