View Full Version : Urea
I've been using straight Behlens hide glue but at the '06 symposium Nugget had his concoction to use to set tonebars which was the focus of the workshop. (By the way, everyone who attended now knows how to determine the shape and size of a Loar tonebar and how to accomplish carving them that way).
The straight Behlens isn't pleasant smelling but not that bad. But Nuggets stuff was absolutely foul, some of the nastiest, vile, repugnant stuff you've ever smelled. So you know it has to be good.
He adds urea to get a longer working time with it. So the question is where do you get it and how much do you add?
Uh, well, ah-hem, urea? Where do you get it? Don't you know what that is? Yup. That's right.
"Urea, also called carbamide, is an organic chemical compound which essentially is the waste produced when the body metabolizes protein. It is a compound not only produced by humans but also by many other mammals.
"Manufactured in the liver, by broken down protein or amino acids, and ammonia, the kidneys transfer urea from the blood to the #####. The average person excretes about 30 grams of urea a day. Urea is one way physicians can detect diseases and disorders that affect the kidney, such as acute kidney failure or end-stage renal disease (ESRD). The blood urea nitrogen (BUN), and the ##### urea nitrogen (UUN), tests, which measure urea nitrogen levels in the blood and #####, respectively, are often used to assess how well a patient's kidney is functioning. Increased or decreased urea levels, however, do not necessarily indicate kidney problems, but can represent dehydration or increased protein intake.
"Urea was discovered in 1773 by the French chemist Hillaire Rouelle. In 1828, just 55 years after its discovery, it became the first organic compound to be synthetically formulated, this time by a German chemist named Friedrich Wöhler, one of the pioneers of organic chemistry. Today's urea manufacturing process was discovered in 1870 and is characterized by dehydrating ammonium carbamate under conditions of high heat and pressure."
"Urea is a nitrogen-containing chemical product which is produced on a scale of some 100,000,000 tonnes per year worldwide.
"Urea is produced commercially from synthetic ammonia and carbon dioxide. Urea can be produced as prills, granules, flakes, pellets, crystals and solutions.
"More than 90% of world production is destined for use as a fertilizer. Urea has the highest nitrogen content of all solid nitrogenous fertilizers in common use (46.4%) It therefore has the lowest transportation costs per unit of nitrogen nutrient.
"Urea is highly soluble in water and is therefore also very suitable for use in fertilizer solutions (in combination with ammonium nitrate: UAN), e.g. in 'foliar feed' fertilizers.
"Solid urea is marketed as prills or granules. The advantage of prills is that in general they can be produced more cheaply than granules which, because of their narrower particle size distribution have an advantage over prills if applied mechanically to the soil. Properties such as impact strength, crushing strength and free-flowing behaviour are particularly important in product handling, storage and bulk transportation."
Here is where I get mine.
By the way, be cautious about using urea derived from dogs (once an important source) unless it's highly purified, or you might find other dogs wanting to leave their mark on your mandolin.
Also, for many centuries urea (directly from #####) [what's up? Is that a naughty word?] was used to set dyes in fabric, and I know that in the middle ages there were dyers who would send their servants around the village every morning to collect the night's accumulation. It was considered best after it had aged a few weeks. Imagine!
Bluemountain, I was hoping to get a bag or bottle of it, not "make my own".
Wsm, thanks, that's what I was looking for. Not something you can find at Walgreens, at least I don't think you can.
Bluemountain, good thing he didn't ask where to get real Indian Yellow.
Maybe we can learn how to make a watch if we ask him what time it is. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/laugh.gif
I got some urea from a "tie dye" kit, and apparently you can get it at stores where they sell dyes for fabric. This paragraph is from frets.com:
"Urea will extend the working time of the glue, and will not weaken the adhesion if it is mixed with the glue just before use. More than 5-10% urea (by dry weight) may increase the flexibility of the dried glue; it may allow glue joints to “creep” more, especially in heat stress. Most instrument builders and repairers try to avoid having to use urea."
I've been told that there is no loss of strength if the urea is freshly added but that chemical changes take place in the glue/urea mixture if it's left in the glue pot for very long and that the glue looses strength. I don't know how long you can keep it in the glue pot and still have strong joints, so for joints where I need extra working time (like gluing plates to rims), I add a pinch of urea crystals to a small batch of glue right before I'm going to glue the joint, make the glue joint as soon as the crystals dissolve and mix into the glue, then discard the batch of glue.
Years ago when I taught Chemistry we did Wöhler's synthesis of urea. One of the students parent was a nurse at the local hospital. Don't know how well it sticks to mandos but it does stick to the nose. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/tounge.gif http://www.mandolincafe.net/iB_html/non-cgi/emoticons/tounge.gif