DIYAPASON-L Digest #553 - Friday, April 5, 2002
Spencer inlet
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Fish Glue... Is it the Age of Aquarius yet?   (X-posted)
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(back) Subject: Spencer inlet From: <> Date: Fri, 5 Apr 2002 15:54:22 -0600 (CST)   As much as I am loathe to disagree with my esteemed colleague, the intake on a spencer is very important. It's function is to straighten the airflow prior to the first impeller. There is a measurable loss of output without it. This is not to say that the blower will not function, or that it will not power an instrument, but there will be a loss of efficiency. Kurt    
(back) Subject: Fish Glue... Is it the Age of Aquarius yet? (X-posted) From: <> Date: Fri, 5 Apr 2002 18:17:04 EST   Since I already look like Buddha, I have been contemplating my navel,=20 actually trying to remember what it looked like years ago before it=20 disappeared, and my meditation naturally turned to thinking about glue.   What is glue? How does it work? These are truly cosmic questions. After=20 some meditation the answers came to me. (Actually it was medication by=20 Glenfiddich.) =20   Glue is any substance with the ability to be "sticky." At the molecular=20 level "sticky" really means a glue molecule will have an electrostatic=20 attraction to some other molecule, like the molecule of cellulose in wood or= =20 the molecule of leather protein. The cellulose molecule will have a positiv= e=20 charge or negative charge somewhere on the molecule that a glue molecule can= =20 attach to with an opposite charge. In this respect all glues are alike. It= =20 is only when we get down to the rest of the characteristics that=20 differentiation of surf versus turf proteins becomes meaningful.=20   There are now two animal protein glues used in the organ trade. First there= =20 was the time honoured hot horse hide glue which is made by cooking down=20 hooves and skins until a gelatinous protein soup is formed. The second is=20 the fish glue which also is cooked fish protein that becomes gelatinous afte= r=20 lengthy applied heating. Here the two glues diverge to take their own paths= =20 in the universe.   Hot glue is made fresh from dry crystals. I have hot glue dry crystals from= =20 50 years ago that are still good (someday I will get to the bottom of the 10= 0=20 lb. barrel and it was the best $18 I ever spent). It retains only a small=20 amount of water in the dry form so in a sealable container it does not=20 deteriorate with age. Its long chain proteins are very sticky and strong. =20 This gives it high tensile strength and other positive attributes such as=20 cohesive strength which will be discussed later in this article. Hot glue i= s=20 also a thermoset glue. The electrostatic molecular bonds are not strong=20 until the thermal energy of the glue starts to lower. As the glue cools it=20 gels then solidifies as the bonds become increasingly strong. The last step= =20 is the drying of the hot glue as the water that is not bound up in the=20 proteins evaporates. Long chain proteins bound to the materials they are in= =20 contact with remain like little stringy bridges holding on to both sides of=20 the connection. Some failures of hot hide glue have been reported with=20 chrome tanned leathers as the rapid set up time does not let it sink in to=20 set up and make for a good adhesion on the slick surface. (Water thinning o= f=20 the hot glue should take care of that.)   Fish glue is premixed and arrives as a liquid. It is a solvent glue with=20 water as the solvent. Purchasing fish glue means you are buying a lot of=20 water and after paying for shipping you will find the fish glue economy for=20 doing large jobs to be questionable. The protein chains are smaller and tha= t=20 is why it is still liquid at room temperature. Initial stickiness of fish=20 glue is partly due to the water solvent interacting with the proteins. As=20 the water solvent leaves the proteins link up to the materials with which=20 they are in contact. The smaller proteins will not be as strong as the=20 longer proteins of the hot glue but the difference may not be that important= =20 in organ work. Smaller proteins means lower cohesion over greater distances= =20 so thickness of the glue application and multiple applications of fish glue=20 in layers will yield less tensile strength. Again this may not be a problem= =20 in organ work.   Would I worry if I had *correctly* done a whole organ in fish glue? NO ! !=20= !=20 The track record of fish glue that I personally know of goes back to when=20 Thomas Edison used fish glue to laminate rice paper for his record reproduce= r=20 diaphragms on the Diamond Disc Phonograph. I have never seen one of these=20 1912 diaphragms ever delaminate due to glue failure. So I believe that if=20 used *correctly* fish glue will perform well but it cannot be used if thinne= d=20 in any way or if the sample has been frozen for even a second. Due to=20 already having water in it, it does lose strength, goes stale, and can have=20 bacterial or mold growth which will alter it greatly. Just a small amount o= f=20 mold that is invisible will drastically weaken the protein structure the=20 infection is digesting. So, a very limited shelf life is its biggest=20 problem. The protein in the fish glue may have more surface adhesion but=20 there is some question of how the shorter protein molecules react to long=20 term tension. Then too fish glue problems with drying times in very humid=20 climates have been reported but here in dry California I have never=20 experienced a single case of the glue not setting up quickly. Some=20 advantages are gained with fish glue, it is more tacky than hide glue and th= e=20 new chrome tanned thin pneumatic leathers with a tight smooth low porosity=20 surface may need the extra set time for any glue to soak into the material.=20= =20 The extra working time is also a distinct advantage to the amateur organ=20 builder who needs a more extended working time to position the parts to be=20 glued. Fish glue will soak into the wood more deeply than hot glue so you=20 need to use more on joinery and clamping time goes from minutes to a day or=20 more. One last comparison is that while I believe hot glue is stronger than= =20 fish glue I must admit I also believe that under most conditions the fish=20 glue adhesive strength is adequate for almost every organ job if sufficient=20 amounts of the glue are used that will allow for the deeper infusion into th= e=20 wood and leather.   The great unknown about fish glue is the second property of a glue. Most=20 people know that glues have the property of adhesion, the ability to stick t= o=20 different materials but few think about the second important property. That= =20 second property is cohesion, the ability of the glue to stick to itself. Ho= t=20 glue has excellent qualities in both major properties. Fish glue may have=20 less cohesion so that a multiple application is less strong and any distance= =20 between the glued surfaces should be kept to a minimum.   One quick note on the Franklin Liquid Hide Glue. To keep it liquid they add= =20 glycerin plus other additives and this reduces the glues reliability and=20 holding strength. It also has a shelf life problem and cannot take freezing= ..=20 The expiration date really does apply as strength drops with age due to=20 oxidation, protein breakage, and bacterial or mold infestation.   All these things considered, as a purist I reach for hot glue first. It=20 simply cannot be beaten but when a situation comes up where fish glue is=20 expedient I use it without worry. Being an animal protein glue it will hold= =20 well and sand down when dry so the next rebuilder will not curse your name.=20= =20 There is no reason to believe that a properly prepared and applied fish glue= =20 will not give good service for the life of the materials it is bonding=20 together.   Lastly, to get on my usual soap box, I think we all agree NO casein based=20 glues (Elmer's, etc.) or PVCs, PVAs, BVDs, etc., should ever be used to hol= d=20 leather or any pneumatic material onto wood. Anything that has to be rebuil= t=20 should have an animal protein glue.   Best wishes to all,   Al Sefl Who still thinks horse glue tastes better than fish glue...   Just don't let PHTA know that pigs, horses, sheep, and shellac bugs died for= =20 the sake of a theatre organ.... adding fish might just be the final straw..= ..   As for Earth Firsters, don't anyone tell them about how much old growth=20 timber it takes for one 32' Diaphone pipe! They would go apoplectic.   Is any of this worth worrying about? Nope, as culture shift relegates the=20 pipe organ to the trash heap of history, the kind of glue you use won't=20 matter a bit. So how many new theatre organs devotees have you enlisted thi= s=20 year? The last decade?   =A9reserved - 2002 -=20   Fish Glue? Far Out Dude... well I am from San Francisco and first lived=20 above Haight & Ashbury at 1433 Haight Street where I grew to love the old=20 "Iron Monster" street cars that shook the street as they went by... they=20 would have scared the stoned hippies beyond belief had they not been pulled=20 years before...