Choosing the Right Glue

The glue you choose to use on your model bridge (or model airplane) can make or break it. I’d venture to say that glue choice is just as important as your wood choice, which makes it pretty important.

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.

All These Glues I’ve Personally Used

All the glues on this page are ones that I have used extensively, both in model bridge building and other wood working creations. While some might be better in specific situations than others, all of these are solid choices. The links below are Amazon affiliate links, which allow me to help support this site when you make a purchase.

What you want to look for in glue:

Generally speaking, these are the factors that you need to consider when choosing a glue. You will need to strike a balance, since there is no such thing as a perfect glue. Or is there? Let me know in the comments.

  • Drying time
  • Price
  • Weight
  • Strength
  • Ease of Use

CA Glue (cyanoacrylate) aka Super Glue
This is a very common glue used for a variety of projects. It generally dries in seconds. It is also widely available. You’ll find it in virtually all big box stores, online, and most hobby stores. However, it is not cheap and doesn’t have a super long shelf life.

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. It is also handy to have around the house for other things as well.

Lately I’ve been trying out the Gorilla Glue Gel CA, and it has proven useful in a number of cases.

CA Glue Pros:

  • Dries quickly
  • Strong when used correctly
  • Good strength to weight
  • Bonds to most materials, especially wood

CA Glue Cons:

  • Dries quickly (see what I did there)
  • Very easy to glue fingers together
  • Bottles can get clogged and dry out completely in a relatively short amount of time
  • Relatively expensive

Purchase Pro CA Glue 1/2 oz Thin

Official Wood glue, such as Elmer’s or Titebond
Wood glue, just like it sounds, is great for wooden model bridges. Also known as PVA glue. I’ve used both Elmer’s and Titebond, both for model bridges and other wood working projects and to be honest, I can’t tell a difference. (Titebond does make a waterproof version). Both seem excellent at what they do.

For model bridges, the main downside to standard wood glues is that they are relatively heavy. However, you can reduce weight by thinning the glue with a bit of water. In some cases, this allows the glue to seep into the wood, creating a stronger joint.

Wood Glue Pros:

  • Strong
  • Gives time to work before setting up
  • Readily available

Wood Glue Cons

  • Takes time to dry (sometimes this can feel like forever)
  • Heavy

Buy Carpenters Wood Glue by Elmers from Amazon

White Elmer’s glue
Not to be mixed up with the brown wood glue version, this glue is perhaps the most common glue on the planet. Well, I’m not 100% sure about that, but I do know it is used everywhere from schools, arts and crafts, to general use around the house. It usually dries in 30 minutes or less, depending on the amount used.

It is, like the marketing says, an all purpose glue. It is a good enough adhesive for a lot of materials. However, it isn’t what I would call a performance glue.

White Glue Pros:

  • Cheap
  • Good enough for a lot of things
  • Dries fairly quickly

White Glue Cons

  • It wasn’t made to be a performance glue

Buy Elmer’s White Glue

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. Generally speaking, the slower the drying time, the stronger the bond.

The trouble with epoxy is that you have to mix it. While I had great success with it for my early bridges, I stopped using it due to one bridge breaking because I didn’t mix it correctly once. I discovered that it was hard to mix it correctly in small amounts, and I ended up wasting a lot of glue because I never knew exactly how much I would need.

Epoxy Pros:

  • Very strong when mixed correctly

Epoxy Cons

  • Can be hard to mix correctly
  • Feels wasteful when you mix too much

Purchase PermaPoxy 5 Minute General Purpose Epoxy

Special Glues:

Probond / Gorilla Glue
This is polyurethane based glue and is super strong. I think Probond came out first, but I’m not completely sure about that. Since then, Gorilla Glue has taken over in popularity. It is not light, but you don’t have to use very much of it. It is also somewhat expensive.

It takes at least 4 hours to set, and your pieces have to be clamped together while drying. I still keep a bottle of it on hand, because it works for about anything.

Gorilla Glue Pros:

  • Super strong

Gorilla Glue Cons

  • Requires clamping
  • Takes forever to cure

Elmer’s Probond Wood Glue 16-Ounce

Weldbond
Weldbond is in a similar class as wood glues, but has some unique properties. Namely, unlike the typical PVA wood glues, Weldbond is white and dries completely clear (wood glue dries yellow). I really like this feature because I think it looks nicer.

I really like using this glue.

Weldbond Universal Glue 8 oz Bottle

As I mentioned at the top, these are the glues I’m familiar with. If the type of glue you use is not listed, leave a comment below and let us know about it.

Chart Comparing Glues (obviously biased by my experience)

 Wood GluesCA GlueProbondWeldbondEpoxyWhite Elmer’s
Strength3/54/55/54/54/52.5/5
Price3/52/52/54/53/55/5
Weight3/55/52/54/52/53/5
Drying Time3/55/52/54/52/53/5
Ease of Use4/53/53/55/52/55/5
Average3.2/53.8/52.8/54.2/52.6/53.6/5

Conclusion

I’ll summarize with a few scenarios. If I was…

  • Building a high efficiency bridge: I’d probably use one or both of CA and Weldbond
  • Building a for fun bridge, or building one with my kids: Elmer’s White Glue
  • Building for speed: CA Glue hands down

Additional Resources:

56 thoughts on “Choosing the Right Glue”

  1. 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

    Reply
  2. 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.

    Reply
  3. 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

    Reply
  4. 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?

    Reply
    • 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.

      Reply
    • 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!!!

      Reply
  5. 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?

    Reply
    • 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.

      Reply
    • 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!

      Reply
  6. 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.

    Reply
    • 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,

      Reply
  7. 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

    Reply
  8. 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.

    Reply
    • Used to build model aeroplanes back in the ’60’s (Comet Model Hobbycraft kits mostly) and ran across this website. Was wondering if the old glues we used then were still the best and considering the fact I’ve had experience with them anyway will probably stick with them (pardon the pun) for the F4D Skyray I built in Oct’61. Found the plans & patterns on the web. This oughta be good.

      Reply
  9. 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.

    Reply
    • 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?

      Reply
  10. Oh… Well, thank you anyway for taking time to respond to my question :). What glue would you recommend for balsa wood? Thanks SO much.

    Reply
  11. I tend to use a hot glue gun for my model. It isn’t very light, but you don’t need much and it is very strong. I used balsa wood.

    Reply
  12. I love using just regular wood glue for building a bridge. It is so easy to use and it doesn’t add a lot of weight to your bridge if you know how to use it correctly. It is made for wood so why wouldn’t you use it? That is what I would recommend for anyone who is or wanting to build a model bridge.

    Reply
  13. Hey garrett boon. I was wondering if you could answer a few questions for me. Okay here it goes… 1) When building a bridge , does the type of glue used effect the outcome of the bridge, the amount of time given to let the glue bond with the wood, both, or neither? 2) Since a warren truss bridge’s design is basically zig-zags, does the zig-zag design help distribute the amount of pressure put on the bridge when weight is applied or does the design have a different purpose? Why or why not? 3) Why is it so important that when building a bridge that each side should be as symetrical as possible? 4) When building a bridge, why does connecting to ends of wood with accurate angles, instead of regular flat ends, help the bridge withstand more pressure? 5) Does every bridge have weak points? If so, why? 6) Does the weight of the wood used in building a bridge affect the amount of pressure the bridge can withstand or is it just the design you use? 7) What is the best design for a bridge if the goal is to hold as much weight as possible but the bridge is to weigh no more than 16 grams? Please answer these questions ASAP. Thanks for your help.

    Reply
    • Arianna, here are the answers to your questions.

      1. Yes, both affect the bridge. Some glues are stronger than others. If you test your bridge without letting the glue dry properly, then obviously it won’t hold as much as it could have. Usually 24 hours is enough time for any glue to completely cure.

      2. It is correct that a Warren truss looks like a bunch of zig-zags. But what makes the Warren truss strong is simply the fact that it is composed of triangles. The triangle is the strongest shape to use on a model bridge.

      3. There is a difficult concept behind this answer. Part of it is related to the actual construction. If your bridge is not symmetrical, then probably the overall construction of bridge is not the best. A symmetrical bridge also has a greater capacity to distribute the weight throughout the bridge.

      4. I think you are talking about mitered joints. The reason a mitered joint is stronger than a regular end joint is simply the added surface area for the glue. However, an even stronger joint to use a lap joint.

      5. Every bridge will break eventually if enough force is applied. Most bridges do have weak points, but those weak points are engineered to be so strong that they will not break under normal circumstances?

      6. The weight of the wood is not directly related to the strength of the bridge. Instead, the density and stiffness of the wood are more important.

      7. Your best bet is to use all of your allocated 16 grams. I can’t tell you the best design to use, because that is usually a matter of debate. Use a standard truss as they are very solid designs.

      Reply
  14. Hey Garrett,I want to build truss bridge with glue and toothpicks.otherwise,the bridge must have a mass less than 50 grams but 30 cm long ,4 cm wide and 5 cm hight,at least.what I gonna do?which kind of glue should I use, CA glue or weldbond ?By the way,the bridge must hold the weight about 400 times compare with its mass.What I gonna do,should I build a truss bridge,Kingpost,queenpost or X-Herrn bridge?

    Reply
    • Christopher, my expertise is not in toothpick bridges. But I would recommend CA glue over Weldbond for a toothpick bridge.

      Reply
  15. Hey Garrett, I tried using Weldbond but because of its slow setting time, I want to try using CA glue. Would you recommend just regular Super Glue or Super Glue Gel? The “minimizing weight while gluing” article in additional resources said to use the “thin stuff” but I don’t know whether to use the regular (liquid) one or the no-drip gel one because even though it says that wood works best with the gel, it might not be the best choice.

    Reply
    • Hi DK,

      You should use the gel glue. DONT use the liquid glue. I tried using it but it just didn’t work out. I am currently building a balsa/basswood bridge and here is the glue I am using:
      You can get it at Michaels for about 3-4 dollars. Its really good. It has a light blue cap and it’s called Gorilla Glue. It does miracles on wood bridges. Also it’s strong and lightweight. Go ahead and try it!

      Reply
      • I’m using Gorilla glue and it seems to be the best wood glue I’ve found – goes tacky dry in about 40 minutes and sets hard in 8-10 hours depending on the gap. But you can continue working if you’ve got enough clamps and rubber bands.
        PVA based glues don’t like big gaps. Pull everything tight-ish and things work out well.

        Reply
  16. Well for my science class we were given the option to do an experiment or build I a bridge I chose the latter of the two. I followed your instructions about buying sheets and cutting and I was able to set up a jig to cut the pieces i needed and everything was going great I had my sketches on graph paper and supplies next to me my hands were clean but when i went to to glue my first pieces together to build the frame of my K-Truss ( I used Welbonde but also I didn’t mix it with water because I am not sure how too) and i started to glue the first two joints and they didn’t work so i decided to wait 4 hours for it to bond. After Four hours i checked in it still hadn’t bonded so i decided to use some Elmer’s Carpenter glue. Same result as the previous. Then i tried plain old glue (paste). And after a that on the verge of losing it I pulled out extreme adhesive paste and Krazy glue. And surprisingly when i combined them it worked but not that well. Could you please give me some advice about glue also if it helps the requirement are as follows for:
    2.38 mm balsa must weigh 16.0 grams or less base must be 45.0 cm horizontal opening must be centered and a with a width of 26 cm or more must have a central vertical opening 8 cm or higher and spanning the width of 26 cm or more the height of the bridge must be 13 to 25
    and width of the bridge must be 11 to 12 cm at the base but there is no limit at the top.
    -thank you very much for all the help-

    Reply
    • First Timer, thank you for your comment. What do you mean when you say the glue had not bonded after 4 hours. By that time the glue should have “set”. That means the glue will be starting to get hard but it will not be full strength yet. Krazy glue is the only glue you mentioned that will have cured in a very short time. The others take 24 hours to reach full strength.

      I would caution against combining glues. Sometimes the chemicals in different glues could create a very harmful mixture.

      Reply

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