Choosing the Right Glue
What you want to look for in glue:
- Drying time
- Price
- Weight
- Strength
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.
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.
Titebond Wood 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.
Other wood glues. There are many other wood glues out there. One of the major brands is Titebond. It acts very much like Elmer’s wood glue. It is strong, heavy, and widely available. All glues will dry faster when you use small amounts. Mixing it with water also makes it dry faster.
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.
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.
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.
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 | 3/5 | 2/5 |
| Price | 3/5 | 2/5 | 1/5 | 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 | 1/5 | 4/5 | 3/5 | 3/5 |
| Average | 3/5 | 4/5 | 2.25/5 | 4.25/5 | 2.75/5 | 3.25/5 |
Obviously this chart is biased to my own experience with these glues. Please share your thoughts and experiences by leaving a comment.
Additional Resources:
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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.
I use Gorllia glue. Is that okay?
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 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.
awesome opinions i think i know what glue to use
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