Rookie help understanding glue
04-20-2023, 05:08 PM
#1
Rookie help understanding glue
I am starting my very first kit and am a bit overwhelmed at the glue choices.
the instructions specified epoxy for some piece but nothing for most.
Can you help me understand where I should use CA, where I should use titebond original and where I should use epoxy?
TIA!
the instructions specified epoxy for some piece but nothing for most.
Can you help me understand where I should use CA, where I should use titebond original and where I should use epoxy?
TIA!
04-21-2023, 04:22 AM
#2
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They all work and will make a joint that is stronger than the surrounding wood. And your question could devolve into the old Ford vs. Chevy debates. Epoxy will be the heaviest (not ideal for a flying machine). Titebond will be the least expensive. I am among the many people who have developed an allergic reaction to CA and therefore minimize the amount I use. But it is the quickest. If I could use only one glue to build a complete model it would be Titebond. And I have done this including those spots where epoxy is recommended. Way back when I started building models I built the whole thing from Ambroid. Now I use very little epoxy and Titebond for most joints.
Chuck
.
Chuck
.
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Steelman93 (04-21-2023)
04-21-2023, 05:45 AM
#3
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Good questions, OP. Here is some stuff to chew on:
When instructions call for epoxy for some pieces, that is because an extra strong glue joint is structurally critical there, such as at a firewall (where the engine or motor mounts), landing gear mount or wing mount. Epoxy generally has the greatest strength (as well as shock-resistance), but it is heavy, so it should only be used when really necessary. It is generally glow fuel-proof. Keep in mind that the longer it takes to cure, the stronger it will be. I haven't bought 5 minute epoxy in over 20 years, because if I am going to put down that kind of weight, I want it to be strong, and 20-30 minute epoxy is FAR stronger than the 5 minute crap. If I can wait 5 minutes, can't I wait 20-30, especially if it nets me much more strength at the same weight?
Cyanoacrylate (CA), aka Superglue, sets up in seconds, is relatively light, but strength is dependent on a solid, tight glue joint. CA is great for balsa-to-balsa (soft, porous wood), but not so great on hardwood (including the surface of plywood). CA also produces fumes that cause problems for some people. I rarely use CA, except for tacking things together with it while some better glue dries. It gets on your fingers and will not come off for days. It irritates my eyes and screws up my eyeglasses if I don't take them off - I hate the crap, for the most part. I am rarely in such a rush that a few hours for glue drying holds me down. I always prefer quality to quantity, and I always prefer the job done right to the job done fast.
Aliphatic (yellow carpenter's glue) is my choice for ALL general glue joints (I like Gorilla brand aliphatic). It is generally stronger and more shock-resistant than CA glue. And the best advantage is that it gets lighter as it dries (water evaporates). CA does not evaporate (much, if any), and therefore does not get lighter. Neither does epoxy or polyurethane glue. What you put down is what the glue will weigh on those, because they cure instead of dry (chemical vs physical reaction). Aliphatic (yellow) glue dries as it cures, so it always gets a little lighter. And aliphatic gives an incredibly strong glue joint if the wood fits together relatively well. Aliphatic give you time to work and adjust things for plumb and square before the glue sets up. Get some on your skin? So what - rub or wash it off with water. It doesn't burn your nose or eyes. And you will never, ever instantly glue two fingers together, or glue your X-acto knife or ruler to your hand with aliphatic.
When instructions call for epoxy for some pieces, that is because an extra strong glue joint is structurally critical there, such as at a firewall (where the engine or motor mounts), landing gear mount or wing mount. Epoxy generally has the greatest strength (as well as shock-resistance), but it is heavy, so it should only be used when really necessary. It is generally glow fuel-proof. Keep in mind that the longer it takes to cure, the stronger it will be. I haven't bought 5 minute epoxy in over 20 years, because if I am going to put down that kind of weight, I want it to be strong, and 20-30 minute epoxy is FAR stronger than the 5 minute crap. If I can wait 5 minutes, can't I wait 20-30, especially if it nets me much more strength at the same weight?
Cyanoacrylate (CA), aka Superglue, sets up in seconds, is relatively light, but strength is dependent on a solid, tight glue joint. CA is great for balsa-to-balsa (soft, porous wood), but not so great on hardwood (including the surface of plywood). CA also produces fumes that cause problems for some people. I rarely use CA, except for tacking things together with it while some better glue dries. It gets on your fingers and will not come off for days. It irritates my eyes and screws up my eyeglasses if I don't take them off - I hate the crap, for the most part. I am rarely in such a rush that a few hours for glue drying holds me down. I always prefer quality to quantity, and I always prefer the job done right to the job done fast.
Aliphatic (yellow carpenter's glue) is my choice for ALL general glue joints (I like Gorilla brand aliphatic). It is generally stronger and more shock-resistant than CA glue. And the best advantage is that it gets lighter as it dries (water evaporates). CA does not evaporate (much, if any), and therefore does not get lighter. Neither does epoxy or polyurethane glue. What you put down is what the glue will weigh on those, because they cure instead of dry (chemical vs physical reaction). Aliphatic (yellow) glue dries as it cures, so it always gets a little lighter. And aliphatic gives an incredibly strong glue joint if the wood fits together relatively well. Aliphatic give you time to work and adjust things for plumb and square before the glue sets up. Get some on your skin? So what - rub or wash it off with water. It doesn't burn your nose or eyes. And you will never, ever instantly glue two fingers together, or glue your X-acto knife or ruler to your hand with aliphatic.
04-21-2023, 05:49 AM
#4
Thank you both for the replies, this was clear and helped me a lot
I have built heirloom quality furniture in my past and know the types of wood glue well….this was a great explanation
titebond it is!
I have built heirloom quality furniture in my past and know the types of wood glue well….this was a great explanation
titebond it is!
04-21-2023, 06:53 AM
#5
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Steelman93. it sounds like you are off to a good start, since you already know how to precisely cut and glue wood. I do regular woodworking too, so I spend mucho time in my workshop.
Some other things I forgot to mention: Aliphatic sands not great, but ok. Meaning, if you have some glue squeeze-out from your balsa joint, it is relatively easy to sand it clean. CA glue doesn't sand worth a flip. Epoxy is generally too gummy to sand, at least for a few days, but that is for epoxy glue. Epoxy finishing resin can be sanded much sooner, because it gets more brittle quickly. Polyurethane glue (like Gorilla brand) sands somewhat like aliphatic, if I recall correctly. As you probably know, if there is moisture in the air or in the glue joint, then polyurethane glue tends to expand as it cures, "foaming out" of the glue joint. That can be problematic, so I don't use it too often on airplanes. But there are situations in repairs when that foaming action can come in real handy.
As a side note, the term "Gorilla glue" is commonly meant to be their polyurethane glue. However, Gorilla now makes all kids of different varieties of glues, from aliphatic to epoxy to polyurethane, so now the term "Gorilla glue" could mean just about anything besides just polyurethane. I like their aliphatic glue because it seems to be a little thicker, and easier for me to put onto a glue joint or build up a fillet.
I love glues.
Some other things I forgot to mention: Aliphatic sands not great, but ok. Meaning, if you have some glue squeeze-out from your balsa joint, it is relatively easy to sand it clean. CA glue doesn't sand worth a flip. Epoxy is generally too gummy to sand, at least for a few days, but that is for epoxy glue. Epoxy finishing resin can be sanded much sooner, because it gets more brittle quickly. Polyurethane glue (like Gorilla brand) sands somewhat like aliphatic, if I recall correctly. As you probably know, if there is moisture in the air or in the glue joint, then polyurethane glue tends to expand as it cures, "foaming out" of the glue joint. That can be problematic, so I don't use it too often on airplanes. But there are situations in repairs when that foaming action can come in real handy.
As a side note, the term "Gorilla glue" is commonly meant to be their polyurethane glue. However, Gorilla now makes all kids of different varieties of glues, from aliphatic to epoxy to polyurethane, so now the term "Gorilla glue" could mean just about anything besides just polyurethane. I like their aliphatic glue because it seems to be a little thicker, and easier for me to put onto a glue joint or build up a fillet.
I love glues.
