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Guess what I found out today is methyl cellulose? Some dietary fibre additives, such as Citrucel here in the U.S. Since the lesser grades of art methylcellulose cost between $6 and $9 for 4 oz., and I saw an ad today for Citrucel at less than $10 for what looked like at least 8 oz., I'm thinking about trying the unflavored kind in paste.
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Interesting!
I went to answers.com at http://www.answers.com/topic/methylcellulose
for more info. Be sure to read all the way down the page.
The info says that " it is not digestible, not toxic, and not allergenic".
It also says "Methylcellulose dissolves in cold water... the chemical is not soluble in hot water, which has the paradoxical effect that heating a saturated solution of methylcellulose will turn it solid, because methylcellulose will precipitate out... Preparing a solution of methylcellulose with cold water is difficult however: as the powder comes into contact with water, a gluey layer forms around it, and the inside remains dry. A better way is to first mix the powder with hot water, so that the methylcellulose particles are well dispersed in the water, and cool down this dispersion while stirring, leading to the dissolution of those particles."
Citrucel is a well-known brand name. It also comes in less-known generic brands, which are probably even cheaper.
Thanks, Gwyneth! More experiments!
Sue
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The problem would be determining what fiber supplement is what kind, I think (don't have any in the house so can't look at ingredients)...they may just say "natural vegetable fiber."
The only reason I found out about Citrucel is that my expensive "art" methylcellulose came with no mixing proportions and said to mix with hot water. I have always mixed with cold and was taught that, in fact, it's insoluable in hot water. In the process of reading way too much about methylcellulose chemistry I discovered that it grades all the way from wallpaper paste to...food additives and fiber supplements. Citrucel was the only brand mentioned.
That said, however, I got to thinking about other vegetable fiber additives. They may be even better for our purposes than methyl cellulose. I can't remember what's in Metamucil but I think it's some kind of ground seed. We learned in food chemistry a century or two ago that plant fibers form a spectrum from totally soluble to almost insoluable, or, in terms of food, oat bran to pectin to sawdust (a sterilized version of which was added to a commercial bread--made by Wonder!-- several decades ago as a low-calorie filler).
Anyway, the 'mucil' in Metamucil refers to mucilaganous gel fibers, which are somehow connected to mucilage, formerly sold in great quantities to children who were too old for paste and not old enough for glue. The last time I saw Metamucil was at least 15 years ago, but it used to keep absorbing water; it had to be drunk within five minutes or so or it completely gelled up, and at that point you could add an amazing amount of water and it would still be the same consistency. (I seem to remember that Citrucel advertising promotes it as easier to drink or some other quality that Metamucil lacks, which would make sense if they're different fibers.)
Digestively, in fact, the ability of food fiber to absorb water is a major part of all its benefits. But back to papier mache. I'm going to look at the fiber supplements in the drug store to see what's in the colorless and flavorless ones. There's no point in using one with fake flavor and sugar and making things even tastier for the mice (the main reason I was using methylcellulose in the first place!)
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I meant to add that I know oatmeal water has some adhesive properties, because I have a recipe for "cheap pastels" that uses it instead of gum tragacynth.
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Psyllium seed is the source of metamucil you were referring to. I suspect that methylcellulose is the basic general substance, although the specific sources may vary. The ads for Citrucel are very careful not to disclose the source of their main ingredient. Who knows, maybe it is just sawdust!
From the descriptions of methylcellulose in the site above that I listed, it says that it can be washed off. I wonder if this means that it can absorb atmospheric moisture as well? Any thoughts? Living here in the PNW, where the climate is similar to parts of Britain, humidity is always an issue with PM.
Sue
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It may be made from sawdust, but it almost certainly isn't sawdust itself (unlike that filler in the experimental late 70s bread). At the risk of being even more boring (though as one of my food chemistry teachers used to say, if you know why, you can control how) here's the reason.
Plant fiber has a wide range of water absorbility/solubility. The reason oat bran was so hyped is that, unlike wheat bran, it's considered soluble. The cellulose in most of the tree stalk is largely insoluble; that's what makes it "wood". Insolubility is why wood needs to be pulped to be made into paper--grinding breaks down the insoluble cell walls; heating and or chemical treatment help "digest" it.
Sawdust is more soluble than the wood from which it comes, but the basic reason it doesn't become paper when mixed with water is that most of it doesn't dissolve. Wood/sawdust/pulp is a lot like raw potato/raw pieces of potato/mashed potatoes. Instant mashed potatoes are pure potatoes, but they've first been cooked, then dried. Once plant cells can absorb water, whether naturally or through heat and or chemical treatment ("digesting") the water can be removed and the resulting product can be rehydrated more (methyl cellulose) or less (paper) easily.
Solubility, of course, is a huge factor in papier mache; as Jackie's experiments outdoors show, it affects virtually every aspect. At the beginning, we want more solubility; at the end, less or none.
The more "fibery" plant material is, the less soluble. Plant cells are (very simplified) sugars, starches, or celluloses. The sugars dissolve very readily, starches less so, and pure untreated celluloses least. This helps explain why starches make better adhesives than methyl cellulose.
With chemicals, time and or heat, the sugars, starches and celluloses can change. Adding baking soda (alkaline) to water makes vegetables soften more quickly as they cook. After corn is picked, the sugars rapidly covert to starches. When potatoes are cooked, much of their cellulose becomes starch. Part of this is true conversion, part is because cell walls break down and release the wet stuff inside. The term "mache" is dead on; human digestion starts with chewing, where saliva and breaking down cell walls make starches turn to sugars (why chewing a cracker makes it taste sweet).
Cooking a starch and water mixture enables the cell walls to absorb more water, creating a gel. That's why cooked paste is stickier than raw paste. Cooking also makes paste harder and less re-soluble after the water evaporates; it makes osmosis (movement of water through cell walls) much tougher.
But not tough enough, which is why water resistance is a problem. It takes synthetic plastics to prevent osmosis entirely, although some natural substances are better than others. Since fats are completely insoluble, oilier woods such as teak, resist water better than woods with less oil, such as most pines. As it oxidizes, linseed oil becomes harder and harder because several processes occur, of which evaporation is the simplest.
Anyway, chemical treatment with methyl or ethyl (both alcohol which is also a product of plant sugar changes) breaks down the cell walls in wood cellulose to make it soluble enough to gel.
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