Choosing the Right Glue
The glue you choose to use on your model bridge (or model airplane) can make or break your structure. I’d venture to say that glue choice is just as important as your wood choice, which makes it pretty important. If you build your bridge with a weak glue, then no matter how good the design is your bridge will not perform well. This article compares and contrasts different types of glues, showing the strengths and weaknesses of each so that you can make an informed choice for what glue to use on your bridge.
What you want to look for in glue:
- Drying time
- Price
- Weight
- Strength
- Ease of Use
CA Glue
This is a very common glue used for a variety of projects. It dries in seconds, like super glue. It is also widely available. Numbers of hobby stores and online companies sell it. However, it is not cheap. CA glue can be bought in three types: thin, medium, and thick. The thin stuff is very light, but not especially strong. The thicker stuff is heavier, but stronger. I have known people to build extremely efficient bridges using CA glue. I do know that I will never use regular super glue after seeing how much better CA glue is. Purchase Pro CA Glue 1/2 oz Thin
Elmer’s Carpenter Wood Glue
This wood glue is very well known and well used. Elmer’s makes a solid glue, although I see it as on the heavy side. If you want to go with a good glue, then this is a good choice. Remember that with wood glue, you can actually get a stronger joint by adding a little bit of water to the glue. This allows the glue to seep into the wood, creating a stronger joint. Buy Carpenters Wood Glue by Elmers from Amazon
White Elmer’s glue
This glue can be bought anywhere, and is relatively cheap. It usually dries in 30 minutes, which is somewhat long for building bridges. Also, it is not very light or strong. I have come to the conclusion that white Elmer’s glue is not a good choice for model bridge building. Buy Elmer’s White Glue
Titebond Wood Glue
This glue bonds balsa wood very well. It also can be found in most hardware stores. However, it is fairly heavy. Many people mix water with the glue to cut down on weight. It dries fairly quickly, less than 10 minutes in small amounts. Elmer’s wood glue also provides a strong joint. The reason I don’t use this glue is because I don’t think that it is the best. But it is still pretty good. Titebond III Ultimate Wood Glue, 8-Ounces
Epoxy. The first glue I ever used in building model bridges was 30-minute epoxy. I liked it because it was very strong and could be bought at many stores. Epoxy comes in several different “setting times”. You can get 90 second, 5 minute, 15 minute, 30 minute, and up to 4 hour epoxy. The bad thing about epoxy is that you have to mix it. I had trouble mixing it correctly in small amounts. I ended up wasting a lot of glue mixing a lot of it at once. Also, epoxy is not very light. An interesting feature about epoxy, it heats up when curing. Sometimes it can get quite hot. Purchase PermaPoxy 5 Minute General Purpose Epoxy
Special Glues:
Probond
This is polyurethane based glue and is super strong. It is a cousin of Gorilla glue. It is not light, but you don’t have to use very much of it. However, the only place I know of that sells it is a local Ace Hardware store. It is also very expensive, which is why I don’t use it much anymore. It takes at least 4 hours to set, which is a really long time to wait. I still keep a bottle of it on hand, because it works for about anything. Elmer’s Probond Wood Glue 16-Ounce
Weldbond
This is the glue I have switched to, after seeing it at good ol’ Ace. It is lighter than Probond, almost as strong, and a whole lot cheaper. It looks a lot like white Elmer’s glue, but dries completely clear. It sets in no more than 30 minutes, but often in less than 10. Weldbond Universal Glue 4 oz Bottle
If the type of glue you use is not listed, shoot me an email telling me about it at webmaster@garrettsbridges.com
Chart Comparing Glues
| Wood Glues | CA Glue | Probond | Weldbond | Epoxy | White Elmer’s | |
| Strength | 3/5 | 4/5 | 5/5 | 4/5 | 4/5 | 2/5 |
| Price | 3/5 | 2/5 | 2/5 | 5/5 | 3/5 | 5/5 |
| Weight | 3/5 | 5/5 | 2/5 | 4/5 | 2/5 | 3/5 |
| Drying Time | 3/5 | 5/5 | 2/5 | 4/5 | 2/5 | 3/5 |
| Ease of Use | 4/5 | 3/5 | 3/5 | 4/5 | 2/5 | 5/5 |
| Average | 3.2/5 | 3.8/5 | 2.8/5 | 4.2/5 | 2.6/5 | 3.6/5 |
Obviously this chart is biased to my own experience with these glues. Please share your thoughts and experiences by leaving a comment.
Additional Resources:
cannot use superglue????
Thx M8, most people googlein on this subject are like me new to this so its nice to get a simple answer to a simple question, Thx again for takin the time to point me in the right direction with glues, Paul
I’m building a basswood bridge for a school project, and I just wanted to say that this site has helped me so much. The information on different types of glue, differents kinds of joints, and the different kinds of truss bridges has been extremely helpful to me. Thank you very much.
I am going to build a balsa wood bridge. The rules indicate that I can only use 1/8″ x 1/8″ maximum balsa wood; Elmer’s white glue only; span 18″ w/ 1″ bearing at each end; width & height a max of 5″; entire bridge must be able to pass thru a square 5″ x 5″ aperture. Bar will be placed across mid-point to apply the test for structural effuciency. Any advice would be much appreciated. Shoud I use the glue straight w/o any water?, etc
awesome opinions i think i know what glue to use
I am building roughly a 50cm (length) x 19cm (height) bridge out of balsa wood. Would you recommend I use Gorilla Super Glue or Elmer’s Carpenter’s Wood Glue? The bridge needs to be as lightweight and be able to hold as much weight as possible.
I see that hot glue from a gun is not mentioned. Why not? It seems to be strong enough and like CA sets immediately. Any down side?
although hot glue is good an all, it does not have very much rigidity. Because it is just plastic, it does not stick to the wood all that well. and when you put weight on it, the glue will slowly but surely deform and your whole brigde will sag until it finally collapses.
If you’re using hot glue to make a bridge for science olympiad, then it’ll weigh too much. I learned that it’s really strong, so if you don’t care about weight- GO FOR IT!!!
I use Gorllia glue. Is that okay?
What about gorrila glue? I heard it’s the strongest Wood Glue on earth… Why doesnt wood glue work good on popsicle and other wood bridges?
Gorrilla glue is great stuff. It requires that you put water on the wood prior to applying the glue. It will foam and expand to 4X the volume of glue applied. It is very light weight. You will need to clamp the pieces together or they will be forced appart by the foam.
If you use gorilla glue, you’re going to have to start over. It will foam up and cause your bridge to flex and bend. It will hold almost nothing. DON’T USE IT!
Elmer’s carpenters wood glue works great for elevated bridge and The wright stuff!
Can someone explain how to glue the pieces of wood together? When we glue them together they glue to the surface which we are glueing on. We can not think of how to overcome this obstacle? Thanks for any help.
Patty, you can try putting some wax paper down underneath the wood. This will help. The other thing you might want to do is make a big effort not to use so much glue that it spreads everywhere. Typically, if you can see the glue after pushing the pieces of wood together then you are using too much,
I’m doing Science Olympiad also this year. I’ve done tower for the past few years but they’ve done away with it (sad, I know). I’m not on elevated bridge this year because they really needed my plane-building expertise for “Wright Stuff” (Good title, I know). I’m thirteen and just wanted to let you know that this site is very helpful. I showed it to my budy, Ansur, who is doing the bridge event.
Thanks,
Avery
Georgia
I have never built a bridge, but I have been building model airplanes out of balsa sticks for over 40 years. Many airplane builders now use CA glue, but I think the older solvent-based glues produce the strongest and lightest bonds. These glues need to dry overnight for maximum strength. If you need to “unglue” a joint, you can use acetone to melt the glue. Solvent based glues include:
Ambroid cement — This is the best glue for balsa. Amber colored. You can order from http://www.peck-polymers.com
Duco cement — Available in some hardware stores. Dries clear and faster than Ambroid.
Sigment — Very similar to Duco, order from http://www.sigmfg.com
Testors wood glue — very fast drying.
Thank you Walter for your input.
Hi, i am a 13 year old kid who does science olympidad like you did. I LOVE it. I am on elevated bridge and have found this sight to be very helpful. My last bridge weghed 18g and failed at 3kilos =(. My next one which i am confident in will weigh about 10g and i think it will hold. I think its great that you put up this sight its been somewhat helpful. I would just like to point out that some CA glues need an acivator in order for the gule to cure fully. The one i do does and it will hold without it but i just wanted to say that it is important to check if the glue requires an acitivator in order for it to work before you buy it. It would be a real bummer to buy 30 dollar glue and have it not work.
That is interesting, Max. I knew that you could use accelerator for CA glue, but was not aware that some CA glues require some sort of activator. Do you know the names of the brands that need one?