ruk·si

🧪 Glues / Adhesives

Updated at 2023-07-04 04:07

But I've never seen the Icarus story as a lesson about the limitations of humans. I see it as a lesson about the limitations of wax as an adhesive.

- Page 141, What If?: Serious Scientific Answers to Absurd Hypothetical Questions, by Randall Munroe

TL;DR: The Table of Sticky

ThingAdhesive
polystyrene models (*)plastic cement > super glue > epoxy
other modelssuper glue > epoxy
plasticard / styrene sheetSlater's Mek-Pak > plastic cement > super glue
resinsuper glue > epoxy
stonesuper glue > epoxy > hot glue
metalsuper glue > epoxy > hot glue
balsa or cork woodbalsa cement > carpenter's glue > PVA > super glue
other woodcarpenter's glue (**) > PVA > super glue
paperundiluted PVA
cardboardconstruction adhesive > hot glue > PVA
EPS (expanded polystyrene)polyurethane glue > construction adhesive > PVA
XPS (extruded polystyrene)construction adhesive > PVA > hot glue
*) Most plastic model kits are polystyrene, but you can test on the sprue first.
   Polystyrene begins to melt in a minute after adding a drop of plastic cement.
   Test with a toothpick, not with your finger.

**) Note that carpenter's glue can be quite slow to cure though.

***) In general, construction adhesive works great for all large (10+ cm²) surfaces.

Tip: when in doubt, use super glue.

It gets expensive in large quantities but works in most cases.

Glue Types

PVA glue (polyvinyl acetate) is cheap, non-toxic and water-soluble. The main downside is that almost nothing sticks to cured PVA so further modifications require more work. There is a long list of different kinds of PVA that have various viscosity levels and additives included but the core product is the same. For building terrain, you usually want the most undiluted PVA for attaching (the strongest bond) and Mod Podge for sealing surfaces (harder and crystal clear finish). PVAs won't survive freezing. PVA won't work for gluing smooth surfaces, all PVAs are designed to work on porous materials only. PVA needs pressure to adhere properly, so adding weights or clamping is recommended.

Popular PVA brands:
* Erikeeper: high moisture, diluted PVA
* Elmer's School Glue: high moisture, diluted PVA
* Elmer's Glue-All: medium moisture, slightly diluted PVA
* Aleene's Tacky Glue: low moisture, slightly diluted PVA
* Mod Podge: PVA-based sealant with additives for flow, strength, clarity and less shrink

Buy a big bottle of Mod Podge, pour in some black craft paint and you now have a lot of runny glue that you can use both seal and prime terrain in one go.

Carpenter's glue (aliphatic resin) is harder and resists both moisture and heat better than PVA. The main downside is that it cures slowly, usually over 24 h. Also called "wood glue" or "yellow glue" in some places; if the glue is yellow, it's usually aliphatic resin.

Super glue (cyanoacrylate, CA) is of moderate cost and dries quickly. Thin super glue seeps into cracks and soaks to surfaces. Thicker super glue stays where you put it and doesn't soak into things. Note that using a lot super glue heats the applied surface a bit, especially the thin super glue.

Super Glue TypeControlCuring TimeOptimal Use
ThinDifficult5 secAttach small details
MediumManageable1 minStructural
ThickEasy2 minStructural

Tip: to accurately apply thin super glue that doesn't have a needle applicator, run it down a wooden toothpick.

Thin and thick super glue are used differently. With a thick super glue, you add the glue to one surface and attach them. With a thin super glue, you should hold the pieces together and squirt a bit of the thin glue into the microscopic gap between the pieces.

There is also a wide array of special super glue formulations e.g.

  • Zap-O Foam Safe CA: won't melt XPS and styrofoam. Needs a tiny bit of moisture to cure properly so just dampen the surfaces with a wet finger.

Polyurethane glue (PU glue) expands as it cures (most glues shrink), creating a strong, water-resistant bond. For a stronger bond, add a tiny bit of moisture with a damp cloth to one of the surfaces. PU glue lacks moisture, so it's good when gluing paper, cardboard and other potentially warping surfaces if used without water. Fully cures in 24 hours. Popular brands include Titebond, Excel and Gorilla Glue (the original).

Always, always, always use clamps with PU glue as it expands.

Epoxy glue (two component glue) is one of the strongest adhesives, but more expensive. As they are rather clear, they are excellent for creating water, toxic ponds and thick blood splatter when mixed with acrylic paint. Also, as they form really strong bonds, they are good when gluing magnets that naturally have more pull. Mix the epoxy mixture until you feel it's totally mixed, and then some more. Domestic epoxy glues may break after being frozen for a long time. Popular brands include Loctite Heavy Duty Epoxy.

Buy epoxy glue in tubes. Don't buy those dual syringes, it is harder to get equal amounts of components with those.

To fill gaps with epoxy glue, mix some baby powder or saw dust in it.

Hot glue is extremely cheap, cures in 10 seconds and doesn't shrink or expand as it cures. The main downside is that hot glue is very messy. Note that hot glue does heat the applied surface and no shrinking may leave visible gaps. Hot glue is not recommended for miniature assembly but usable for terrain, bases and special effects. Be wary of the short working time before it sets.

Technically, hot glue can ruin magnets as heat can demagnetize them. Shouldn't be a problem when gluing small magnets as there isn't enough heat buildup to cause damage.

Plastic glue (plastic/polystyrene cement) bonds polystyrene plastics together by melting the applied surfaces. Probably the best glue for polystyrene plastic miniatures and especially good when gluing small pieces, but note that it only works when gluing polystyrene to polystyrene. Popular brands include Tamiya Extra Thin Cement and Revell Contacta Professional.

Tip: Tamiya Airbrush Cleaner is 99% the same stuff as Tamiya Extra Thin Cement, but the airbrush cleaner is multiple times cheaper. So, buy 1 bottle of both and just keep refilling the cement bottle.

Construction adhesives are meant for gluing large things together like tiles to walls. In general, they can be used to glue virtually anything together. Construction adhesives are usually more rubbery and messy. Most construction adhesives are silicone-based, which is very toxic. Prefer the products that you can reseal. Most of them need an inexpensive caulking gun. Silicone-based glues might also react with various materials so better to test them first.

Gorilla Heavy Duty Construction Adhesive is my go-to; also comes in small tubes.

Contact adhesives are excellent if you can't clamp the pieces together. Apply even coats of the adhesive to each material you wish to adhere, allow it to dry, and stick them together. Usually leave large visible gaps so not good for miniatures.

Temporary Adhesives

In miniature crafts, you use temporary mounts to keep models in place when working.

Poster putty is the most common temporary adhesive. Blu Tack is the most popular brand, but there are many others. Main downside is that poster butty leaves residue on the surfaces, especially if used for longer.

Double-sided tape works too, but is less reusable. The best use for double-sided tape is to keep things in place when priming as you won't mind much if the tape gets painted.

Sticky gel pads are like double-sided tape (the pads also come in tape form), but you can wash them for reuse and leave no residue on the surfaces. I have no idea how they work, it's like magic.

A tiny amount of super glue works for attaching small parts to metal spikes. The parts are easy to simply snap off later.

Museum putty is essentially premium poster putty. Museum putty and museum wax are meant for keeping art pieces in place. Museum putty is better for miniatures in general. Wax is stronger but leaves some residue behind, which is still a lot easier to clean than poster putty. Place a pea-sized putty/wax piece on a surface, attach an object, and it will stay put. You can twist the object to remove the adhesive, and both are reusable.

Baking Soda + Thin Super Glue

Mixing baking soda with super glue makes in cure instantly to a hard plastic. It doesn't matter if you first apply the super glue or the baking soda. The result is even stronger than just super glue.

You should use thin super glue, medium or thick super glue won't work as well. Extra thin is better but not good as thin, extra thin cures before fully soaking to the baking soda. So, thin super glue with 15+ second cure time is optimal.

Pinning model to base:

  1. drill a hole to a model
  2. add any super glue to a loose pin
  3. slot the pin to the model, clean any excess super glue before it cures
  4. drill a hole to a base
  5. slot the pin to the base
  6. add a drop of thin super glue around the pin from the below
  7. pour baking soda on glue
  8. add a few extra drops of thin super glue
  9. shake off excess baking soda
  10. cut the pin to size

Filling gaps:

  1. gently pour baking soda to the gap
  2. wipe away the excess soda with something flat or your finger
    • don't blow on it...
  3. add a few drops of thin super glue
  4. file and sand it

Filling a hole:

  1. pour a thin layer of baking soda to the bottom
  2. add a few drops of thin super glue on the soda
  3. repeat until filled
  4. file and sand it

Fixing any item:

  1. apply any super glue to the broken connection
  2. attach
  3. sprinkle baking soda along the joint
  4. add drops of thin super glue along the joint
  5. repeat as long as you want
  6. file and sand it

Attaching Legos

The ranking of the best glues to stick Lego blocks (or any ABS plastic) together:

  1. Tamiya Cement for ABS - melts the plastic, there is a brief window to align things, results in a very strong bond
  2. Tamiya Extra Thin Cement - awesome, results in an OK bond
  3. Revell Contacta Professional - awesome, results in an OK bond
  4. Revell Contacta Liquid - messy, but works as well as the Professional
  5. Super glue - sets a lot faster so no time to align which is bad, and the result is a strong bond though

I needed to glue together Legos for a roleplay prototype.

Attaching Cheap Toys

  1. Tamiya Cement for ABS
  2. sprue goo
  3. super glue
  4. hot glue
  5. plastic cement

How to Remove Label Glue

  1. Rub the sticker or sticky area with Turpentine, White Spirit or Glue Remover.
  2. Let it sit for more than 5 minutes.
  3. Peel the glue residue off by rubbing your thumb over it.

Acetone and Isopropyl Alcohol (IPA) are not good for removing any glue.

General Tips

Scratch to bind. To get a better bond with any glue; sand or scratch the surfaces before applying the glue.

Buy your glue in small bottles. Most glues will start to slowly harden when opened the first time; especially super glue. Buy a lot of small bottles, not a few big ones.

Acetone-based super glue accelerator sprays are decent. Good time savings when doing a lot of gluing.

Tip: always store your accelerators away from your super glue 😉

You can create spider webbing with hot glue. Randomly pour hot glue to a container of cold water or on a silicone mat, you can cut the resulting plate to your liking.

Sources

  • Battlefields in Miniature, Paul Davies