Possibly the most essential component to building scale models (beyond the kit) is glue. A model without glue is like a brand new toy sans batteries. It just doesn’t work.
“Alright, give me a tube of it” you say.
“What’s it?” I reply, smiling at the statement's innocence.
Plastic models have come a long way since their origins as a cellulose acetate product. Today they are are primarily made from polystyrene and may include bonus parts made from brass (photo-etch), copper wire, and vinyl. Some specialty kits are even made out of resin. All this is before we get into dioramas which are made from nearly any material you can think of. The predictable result: confusion on which glue to use and when.
But, don't fear! Choosing the right glue is just a simple two step process:
Select the type of glue based on the materials you are bonding together
Select the form of the glue based on attributes that will be desirable for the bond being made
I have structured this post into two key sections. First I will discuss 5 different "core modeler's glues" and second I will briefly describe some "specialty glues". At the bottom of the post I include a a summary table of the 5 core modeler's glues. Feel free to scroll though and stop at the sections you need.
Before we get started on the glue rundown below, always make sure to read and follow the instructions and warning labels on the glue of choice. Formulations and ingredients will also vary across manufacturers, brands, and regions. Editors tip: when working with a new glue or new paint products, always be sure to test for adverse interactions on scrap material or a low visibility portion of the model.
And so we begin...
Core modeler's glue
When we think of plastic models, classic hobby cement is not far in our minds. But, as kits have evolved, so too has our choice of glue. To achieve the best results, a modeler needs to pay attention to the surfaces being bonded (step 1) and the properties of the glue that will be most effective for the task at hand (step 2).
In this section, I cover the 5 most popular types of glue a modeler should know about: classic hobby cement, liquid hobby cement, CA glue, PVA glue, and epoxy.
Classic hobby cement (solvent based)
Nearly everyone introduced to the hobby has used a tube of model cement. This is a gel-like substance that works best when applied to both pieces being bonded together. Holding the parts in place for about 20 seconds is typically enough to form a secure bond, and full curing time is roughly 2 hours.
The active ingredient in these tube glues is typically toluene, a common solvent found in paints, paint thinners, and adhesives alike. It works by melting the plastic surfaces together and forming a weld.
Surfaces typically used for:
Polystyrene - polystyrene
Pros:
Gel-like and will stay on the desired areas of the model
Non-toxic versions are available
Cons:
Can become "stringy" and messy if not used carefully
A small squeeze of the tube tends to ooze much more glue then is desired
Will damage painted surfaces
Avoid using for small and detailed parts
Will "fog" clear parts
Tips:
Squeeze some out into a metal lid and transfer what is needed to the model surfaces with a toothpick
Use for large or complex surfaces that might need more "forgiveness" in curing time
Lightly sanding both surfaces to be bonded may ensure a stronger hold
Liquid cement (solvent based)
Most people building models nowadays use liquid cements. Liquid cements often have the benefit of of drying without leaving behind globs of dried glue. These glues will typically take less time to cure than their thicker classic cement cousins.
Some of the common ingredients in these glues are acetone (a paint thinner and nail polish remover) and butyl acetate.
Surfaces typically used for:
Polystyrene - polystyrene
Pros:
Will dry without leaving globs of glue behind
Great for detailed parts
Most come with a built in brush applicator
Uses capillary action to run along the seam of the surfaces being glued
Different thicknesses are available
Cons:
Can run into undesired areas of the model if not used sparingly
Will damage painted surfaces
Will "fog" clear parts
Tips:
Larger surfaces should be held together by binder clips, rubber bands, and clamps until cured
Lightly sanding both surfaces to be bonded may ensure a stronger hold
Be careful to avoid leaving "glue prints" on the plastic!
CA glue
Also called super glues or crazy glues, these are usually a household staple. CA glues get their name from cyanoacrylates which are a family of compounds. Most modelers use these glues for bonding dissimilar materials like plastic and photo-etch together, or when working with resin.
Surfaces typically used for:
Polystyrene - metal
Metal - metal
Polystyrene - resin
Resin - resin
Pros:
Great for detailed parts
Does not melt plastic
Different thicknesses are available from liquid to gel and have different curing times from 5 seconds to over a minute respectively
Cons:
Can glue your skin together
Brittle bonds are formed and do not hold up to shearing forces
Will "fog" clear parts
Tips:
Squeeze some out into a metal lid and transfer what is needed to the model surfaces with a toothpick
Keep a bottle of debonder (nail polish remover can be used) handy in case you glue something to yourself
If the glue is not curing quickly enough accelerators are available to speed the curing time
PVA glue
PVA glues are known to civilians as white glue or school glue and are made of polyvinyl acetate. Most people have used these glues for paper and other porous craft materials.
Modelers typically require these glues for working with clear parts such as aircraft canopies. In fact, some formulations are even marketed as "canopy glue". Classic hobby cement, liquid cement, and CA glue will "fog" unprotected canopies with their evaporating vapor or leave "ghost" marks if a clear part comes into contact with it.
Some people have also had success using PVA glues with photo-etch parts, but CA glue is usually preferred.
Surfaces typically used for:
Polystyrene - polystyrene (typically reserved for clear parts)
Polystyrene - photo-etch (can be used as an alternative to CA glue)
Pros:
Water soluble
Won't harm paint
Does not leave frosting on clear parts
Dries clear
Cons:
Requires over an hour or more to dry
Will leave globs of glue if too much is used
Tips:
Squeeze some out into a metal lid and transfer what is needed to the model surfaces with a toothpick
Glue can be thinned with a little bit of water
You can make windows out of these glues
Epoxy
These glues are a combination of resin and a hardener. For the glue to work, these two components will need to be mixed thoroughly prior to use (usually 50/50). Epoxy is mostly used by modelers for joining dissimilar materials together. While CA glue can be used for much of the same purpose, epoxy tends to create a stronger bond and may also have a longer set up time which can be advantageous in certain situations.
Due to it's more hazardous chemicals, two-part mixing requirement, and slower drying times, it is the least often encountered of the main modeler glues.
Surfaces typically used for:
Polystyrene - metal
Metal - metal
Polystyrene - resin
Resin - resin
Pros:
Very strong bond
Available in different setting times
Only needed on one joining surface
Cons:
More hazardous
Some do not dry clear
Two-part glue
Tips:
Glue can be purchased in a double-syringe package to ensure equal parts of resin and hardener
Lightly sanding both surfaces to be bonded may ensure a stronger hold
Specialty glues
Whether you are attaching the most delicate of parts to finish your build, or working on an action-packed diorama to show it off, sometimes you just need something special. Here is a brief list of what I have lying around my bench.
Wood glue
As the name implies wood glue is best for bonding wood with wood. These glues are typically a PVA glue (like the ones discussed above) but have been specially formulated to work best with wood. Most of these glues market themselves as having a clear or "natural" color when dry. They tend to dry hard and can be sanded and painted.
Tacky glues
These are typically another formulation of PVA glues that remain tacky when dry. Like other PVA glues they will dry clear. I have used products like Hob-e-Tac and Elmer's Craft Bond glues for dioramas. They are both excellent for laying down shrubs and other landscape details.
Scenic turf glues
Yet another PVA glue. These tend to be thinned down so that they can be applied to large areas via a spray bottle. Some are formulated with a "wetting" agent that will reduce the surface tension of the glue and allow it to flow into cracks and crevices (think ballast of model railroad dioramas) and better penetrate the materials being bonded. They dry clear and matte. If you do use a spray bottle for application, once finished, make sure to cycle plenty of water through the nozzle to prevent clogs.
Future aka Pledge FloorCare Multi Surface Finish aka Pledge Floor Gloss
As confusing as the name of this product is, it is equally useful for modelers. Pledge Floor Gloss (current name) is an acrylic floor polish that modelers often use for sealing in base coats prior to decaling, and decals prior to weathering (the technical details we will reserve for another post). Some modelers have found it useful for keeping clear parts and very small photo-etch parts in place. I have not tried this, but my understanding is that the bond will be just strong enough to secure these highly delicate pieces.
Wrapping up
And there you have it, a list of core glues and specialty glues that should satiate even the most seasoned of modelers. But even with this expansive list there is always something new to learn and explore. So readers, let me know in the comments what other glues you use and the unique ways you use them.
Time to let the glue dry!
Thanks for reading,
Mido
Contact the author: mido@igluemodels.com