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In penence for the binary posting I pumped into some other thread, I’ll post here an answer to a question I asked in yet another thread. I was pondering on the effectiveness of CA for limited applications, knowing full well I had William Tandy Young’s "The Glue Book" sitting unread on my bookshelf. Here, then, is a summary of what I learned from his pages. – Cyanoacrylate glue cures by exposure to moisture into a hard substance very similar to sheet acrylic (plexiglas). [At one time, I was told that CA cures by exposure to oxygen. This turns out to not be true. CA is like urethane glues in this regard. Moisture in the air and in the work surface start the curing process.] – CA is sensitive to the pH of the material applied to. Acidic surfaces act to prohibit curing; alkaline promotes curing. Accelerators are simply an alkaline compound carried in solvent. – Nitromethane and acetone can dissolve cured CA. These are packaged and sold as CA debonders. – CA is one of the few truly structural gap filling adhesives. However, a thinner bond layer makes a stronger joint. – CA makes a strong, durable bond, but is very sensitive to shock loading. That is, striking the joint sharply can break a fully cured bond. I presume this is the typcial mode of failure. Odor-less CA makes a stronger bond, but is even more sensitive to shock. – Shelf life is about 6 months. Thin CA has shorter shelf life than thick; all viscosities thicken with age. Refrigeration before opening can extend this short period; condensaton and precuring are problems if refrigerated after opening. Dessicants in a closed container are useful to extend life. Accelerators or other strong alkaline solutions should not be stored in the same container. – Its fumes are a strong irritant. Contact with the eye can cause permanent damage to eyesight. CA has been linked to occupational asthma (whatever that might be). Skin conditions, ironically, are caused more by the vapors than by direct skin contact. It is not known if they are mutagenic or carcinogenic. – CA cures to an inert solid, so safe disposal is possible. It would be bad to cure the glue for disposal by dumping it in water, or worse, dumping accelerator into the bottle, because the of the fumes produced. In a nut shell… Mike.
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Great post — lots of good information. Thanks! — Ken Vaughn Visit my workshop: http://home.earthlink.net/~kvaughn65/
– Hide quoted text — Show quoted text – In penence for the binary posting I pumped into some other thread, I’ll post here an answer to a question I asked in yet another thread. I was pondering on the effectiveness of CA for limited applications, knowing full well I had William Tandy Young’s "The Glue Book" sitting unread on my bookshelf. Here, then, is a summary of what I learned from his pages. – Cyanoacrylate glue cures by exposure to moisture into a hard substance very similar to sheet acrylic (plexiglas). [At one time, I was told that CA cures by exposure to oxygen. This turns out to not be true. CA is like urethane glues in this regard. Moisture in the air and in the work surface start the curing process.] – CA is sensitive to the pH of the material applied to. Acidic surfaces act to prohibit curing; alkaline promotes curing. Accelerators are simply an alkaline compound carried in solvent. – Nitromethane and acetone can dissolve cured CA. These are packaged and sold as CA debonders. – CA is one of the few truly structural gap filling adhesives. However, a thinner bond layer makes a stronger joint. – CA makes a strong, durable bond, but is very sensitive to shock loading. That is, striking the joint sharply can break a fully cured bond. I presume this is the typcial mode of failure. Odor-less CA makes a stronger bond, but is even more sensitive to shock. – Shelf life is about 6 months. Thin CA has shorter shelf life than thick; all viscosities thicken with age. Refrigeration before opening can extend this short period; condensaton and precuring are problems if refrigerated after opening. Dessicants in a closed container are useful to extend life. Accelerators or other strong alkaline solutions should not be stored in the same container. – Its fumes are a strong irritant. Contact with the eye can cause permanent damage to eyesight. CA has been linked to occupational asthma (whatever that might be). Skin conditions, ironically, are caused more by the vapors than by direct skin contact. It is not known if they are mutagenic or carcinogenic. – CA cures to an inert solid, so safe disposal is possible. It would be bad to cure the glue for disposal by dumping it in water, or worse, dumping accelerator into the bottle, because the of the fumes produced. In a nut shell… Mike.
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Have to disagree about Nitromethane and Acetone. CA is a staple of RC Airplane building, and the Fuel has Nitro in a Methanol fuel in it. In fact, Fuel Proofing of the wood is easily accomplished by application of CA. Acetone is likley does something, but Acetone can used to clean in the areas of CA. Nail Polish remover is also a CA dissolver. CA does not sand! not very easily, anyway
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– <SNIP CA has been linked to occupational asthma (whatever that might be). Skin conditions, ironically, are caused more by the vapors than by direct skin contact. It is not known if they are mutagenic or carcinogenic.
"occupational asthma" primarilywould be an asthmatic condition brough on by continued exposure to air-borne Cyano-Acrylics in ones work place (on the job). Examples of this would be people who work in a CA glue factory, a CA ink making factory, or a press operators in a print shop which uses CA based inks a lot. Axel
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Acetone dissolves it over time. I use a jar of acetone to hold my "tips in waiting" which were tips I carelessly allowed to gum up. The remover they sell smells like nitrobenzene to me. Now that’s a powerful carcinogen. Nail polish remover is basically acetone. – Hide quoted text — Show quoted text – Have to disagree about Nitromethane and Acetone. CA is a staple of RC Airplane building, and the Fuel has Nitro in a Methanol fuel in it. In fact, Fuel Proofing of the wood is easily accomplished by application of CA. Acetone is likley does something, but Acetone can used to clean in the areas of CA. Nail Polish remover is also a CA dissolver. CA does not sand! not very easily, anyway
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Your idea of keeping the tips in acetone might be worth something. email it to these guys. http://www.rconline.com/rcreport/index.html — walk a mile in the other mans shoes before you criticize him, then you will be a mile away and have his shoes!
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Hello Michael, Here is a copy of a recent posting I made to the rec.crafts.woodturning newsgroup, that gives a bit of insight into CA glue, its chemical properties and manufacture: Cyanoacrylates, A Brief Overview: Monofunctional 2-cyanoacrylates were first patented in 1949, but the first viable production process did not evolve until 1954. In the early 1950’s, scientists at Eastman Kodak were working on thermal polymerization and discovered the rapid room-temperature cure and excellent adhesion properties of 2-cyanoacrylates, quite by accident. While working on a freshly prepared monomer, the scientists discovered that the glass prisms of the refractometer has become tightly bonded. Extensive work thereafter, found that many different types of substrates bonded in the same manner. Subsequently in 1958, Eastman 910 debued, the first in a large family of 2-cyanoacrylate ester adhesives. 2-cyanoacrylates polymers spontaneously form (via an anionic/radical mechanisms) when their liquid precursors, or monomers are placed between two closely fitting surfaces. The great utility of these adhesives arises from the electron-withdrawing character of the groups adjacent to the polymerizable double bond. The high reactivity (cure rate) and their polar nature, enables the polymers to adhere quite tenaciously to a wide variety of substrates. Low humidity and/or acidic groups on the substrate surface will slow or inhibit the cure reaction. To extend the usable shelf life, free-radical stabilizers such as quinones or hindered phenols are used. Methyl, Ethyl, Butyl, Allyl and Methoxyethyl esters are available with various setting characteristics and rheological properties. However, the Methyl and Ethyl esters dominate the commercial industrial market. The vinyl structure of 2-cyanoacrylates makes them prone to spontaneous polymerization. The chain propagation can be initiated by ionic or radical mechanisms. The rate of polymerization depends on temperature, humidity, light and the presence of accelerators, like peroxides or bases. In addition to polymerization, 2-cyanoacrylates undergo reactions typical of vinyl compounds, such as addition. 2-cyanoacrylates can be manufactured by many different methods. The base monomers are too thin for convenient use, so thickeners, stabilizers or property-modifying additives may be added. The viscosity’s are available from wicking grades (water thin) to thixotropic gels that range from 20,000 to 50,000 mPa*s for large gaps. The acrid odour of 2-cyanoacrylates, can be effectively mitigated by the substitution of an alkoxyalkyl ester side chain, for the normal alkyl group. Products so modified, are practically odour free, but are slightly less effective as adhesives. The basic method to manufacture 2-cyanoacrylate esters involves preparation via the Knoevenagel condensation reaction (the corresponding alkyl cyanoacetate reacts with formaldehyde in the presence of a basic catalyst, to form a low molecular weight polymer). The resulting polymer slurry is acidified and the water is removed. The polymer is then cracked and redistilled at high temperatures onto a suitable stabilizer combination to prevent repolymerization. Protonic or Lewis acids are typically used in combination with small amounts of a free-radical stabilizer. Although the methods and processes have continually changed and evolved over the years, this is the standard method to manufacture these esters. One recent and significant advancement in the manufacturing process is a continuous process where the condensation is carried out in an extruder. By-products are then removed in a degassing zone and the molten polymer (mixed with stabilizers), is cracked to yield a raw monomer. Recent advances have lead to flexible 2-cyanoacrylate formulas, which remain somewhat flexible when cured. These types of esters are particularly useful to turners when bonding dissimilar materials like stone/metal and wood. The dissimilar expansion and contraction rates of these materials, can cause subsequent failure of the bond when using traditional cyanoacrylates that feature non-flexible, or brittle bonds. Health concerns: A few recent threads have mentioned CA glue and its sharp, pungent fumes/odour. These fumes are not to be taken lightly! 2-Cyanoacrylate esters are lacrimators, even at low concentrations. These esters are irritating to the nose, throat and lungs in concentrations as low as 3 ppm. Eye irritation is typically observed at 5 ppm, or higher. Adequate breathing protection (this means a proper respirator, outfitted with an organic vapour cartridge) is essential when using these adhesives. Additionally, you should not bend over the area, whilst you are applying the CA to the area. If you do not wear a respirator, adequate and thorough ventilation is ESSENTIAL. We are all aware how well CA will bond skin tissues. It’s best to wear protection on your hands when using these products, as well as eye protection if you do not wear a full face respirator. Contact with liquid CA through the clothing will produce a rapid exotherm, which may cause severe burns and scaring. Contact with the liquid CA in the eyes, can cause rapid exothermic polymerization, leading to severe eye injury, or corneal lesions. You should NEVER use CA without proper eye protection. Many turners use CA’s to fill small inclusions, or fissures in turned items either mixed with a filler, or by itself. If you switch on the lathe before complete polymerization has occurred, uncured CA may fly into your eyes, face, skin or clothing. Cured 2-Cyanoacrylate ester polymers are relatively non-toxic. In lab tests, oral doses of 6400 mg/kg failed to kill laboratory rats. Guinea pigs exhibited mild skin irritation, but there was no evidence to suggest sensitization, or absorption through the skin. There is a fire hazard with liquid and cured CA esters, because both forms will support combustion. You should not use these adhesives near sparks, open flames, areas of acute fire hazard or heat sources. Highly exothermic polymerization can occur from the direct addition of various catalytic substances like water, alcohol’s, amines, ammonia, caustics, or surface activator solutions. Take a bit of extra time to insure your protection protocols are up-to-date when using substances that are hazardous. A few seconds of extra time spent protecting yourself, is time we can ALL afford to spend. If you would like to learn more about CA adhesives, look for my upcoming comprehensive article in "Woodturning" (British) magazine. Take care and be safe.
— Letting the chips fly… Steven D. Russell Eurowood Werks Woodturning Studio The Woodlands, Texas Website coming soon! – Hide quoted text — Show quoted text – In penence for the binary posting I pumped into some other thread, I’ll post here an answer to a question I asked in yet another thread. I was pondering on the effectiveness of CA for limited applications, knowing full well I had William Tandy Young’s "The Glue Book" sitting unread on my bookshelf. Here, then, is a summary of what I learned from his pages. – Cyanoacrylate glue cures by exposure to moisture into a hard substance very similar to sheet acrylic (plexiglas). [At one time, I was told that CA cures by exposure to oxygen. This turns out to not be true. CA is like urethane glues in this regard. Moisture in the air and in the work surface start the curing process.] – CA is sensitive to the pH of the material applied to. Acidic surfaces act to prohibit curing; alkaline promotes curing. Accelerators are simply an alkaline compound carried in solvent. – Nitromethane and acetone can dissolve cured CA. These are packaged and sold as CA debonders. – CA is one of the few truly structural gap filling adhesives. However, a thinner bond layer makes a stronger joint. – CA makes a strong, durable bond, but is very sensitive to shock loading. That is, striking the joint sharply can break a fully cured bond. I presume this is the typcial mode of failure. Odor-less CA makes a stronger bond, but is even more sensitive to shock. – Shelf life is about 6 months. Thin CA has shorter shelf life than thick; all viscosities thicken with age. Refrigeration before opening can extend this short period; condensaton and precuring are problems if refrigerated after opening. Dessicants in a closed container are useful to extend life. Accelerators or other strong alkaline solutions should not be stored in the same container. – Its fumes are a strong irritant. Contact with the eye can cause permanent damage to eyesight. CA has been linked to occupational asthma (whatever that might be). Skin conditions, ironically, are caused more by the vapors than by direct skin contact. It is not known if they are mutagenic or carcinogenic. – CA cures to an inert solid, so safe disposal is possible. It would be bad to cure the glue for disposal by dumping it in water, or worse, dumping accelerator into the bottle, because the of the fumes produced. In a nut shell… Mike.
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