Adhesives

Few workshop elements generate more doubts than adhesives. Cyanoacrylate or epoxy? Which one bonds rubber better for a tyre? Which adhesive should I use to join two resin pieces without visible seams? These are questions that any slot racing enthusiast, static modeler, figure painter, or diorama creator has asked at some point, and the answer is not always straightforward because it depends on the material, the mechanical load the joint will bear, and the time we have to work.

Adhesives are one of those consumables that seem secondary until you use the wrong one and ruin a piece you’ve spent hours preparing. Choosing correctly is not complicated if you understand four basic concepts: type of adhesive, curing time, final strength, and compatibility with the substrate. From there, everything falls into place.

At Ministry of Hobby, we work with adhesives designed for the real needs of modelers: from the hobbyist assembling their first static model kit to the competitive driver who needs to secure a chassis with millimetric precision, including the figure sculptor who joins resin casts or the diorama creator who glues wood, polystyrene, metal, and natural textures in the same project.

This guide helps you understand what you have in the catalogue, how each family of adhesives works, and when it’s advisable to use one or another. Without unnecessary technical jargon, with practical criteria and real workshop experience.

What are modelling adhesives and why is it important to choose wisely

An adhesive is any substance capable of joining two surfaces through physical or chemical mechanisms. In modelling, that generic definition translates into a very diverse family of products: from ultra-fast curing cyanoacrylate to two-component epoxy resins, including contact adhesives, polystyrene adhesives, or mounting gels.

The reason why it matters to choose wisely is twofold. First, because a poorly executed joint can break, deform, or stain the piece. Second, because some adhesives chemically attack certain materials: polystyrene can dissolve with incorrect products, polyurethane resin does not accept the same as epoxy, and the synthetic rubber of slot tyres has very different needs than carbon fibre.

In the world of slot racing, moreover, adhesives serve a structural function: securing tyres to rims, ensuring the motor in its mount, gluing bodies, or joining chassis parts. A failure at any of these points during a race has immediate consequences. That’s why a stationery adhesive is not the same as one formulated specifically for the tolerances and vibrations of competitive slot racing.

In static models and dioramas, the requirements are different but equally important: we need adhesives that leave no visible marks, that allow adjustments before curing, or that behave well under layers of acrylic or oil paint.

How to choose the right adhesive

Before buying an adhesive, it’s advisable to answer four questions:

• What materials am I going to join? Not all adhesives are compatible with all substrates. ABS plastic, polyurethane resin, metal, wood, rubber, or carbon fibre have different surface polarities and require specific adhesives or proper preparation.
• How much time do I have to position the piece? The open time —the margin you have before the adhesive starts curing— varies greatly between products. A standard cyanoacrylate sets in seconds; a two-component epoxy resin can give you between five minutes and an hour.
• What mechanical load will the joint bear? It’s not the same to glue a decorative antenna to a hood as it is to secure a motor in a slot chassis. For joints subjected to vibration or stress, we need adhesives with good shear strength.
• Do I need to fill gaps or just make a surface-to-surface joint? Cyanoacrylates work better on very tight surfaces; for joints with some separation, epoxies or filler adhesives are more suitable.

Answering these questions before opening the catalogue saves you unpleasant surprises. And if you have doubts, our team has years of experience applying adhesives in all these contexts: we can guide you straightforwardly.

Main types and differences

The catalogue of modelling adhesives can be organised into several families with well-defined characteristics:

Cyanoacrylates (Super Glue)

They are the fast-curing adhesives par excellence. They work through surface moisture and create very rigid bonds in a short time. They come in different viscosities: liquid (for very tight joints, penetrates by capillarity), gel (for more open surfaces or vertical pieces), and extra thick (for filling small gaps). They are ideal for plastic, resin, metal, and ceramics. Their downside is their fragility against impacts and their tendency to whiten porous or painted surfaces if applied excessively. The use of cyanoacrylate accelerator allows for more precise control of curing.

Two-component epoxy resins

They are mixed in a resin-hardener ratio and cure through a chemical reaction. Their main advantage is the final strength: they withstand vibration, moderate heat, and various types of mechanical stress well. They are perfect for structural joints in slot (mounts, chassis, resin bodies), for gluing metal to plastic, or for filling significant gaps. The working time varies according to the formulation: 5-minute ones are convenient for general use; 20-30 minute ones allow for finer adjustments and usually offer greater final strength.

Contact adhesives

They are applied to both surfaces, the solvent is allowed to evaporate, and the pieces are joined under pressure. The bond is immediate upon contact. They are very useful for flexible materials such as rubber, vinyl, fabric, or foam, and have good peel resistance. In modelling, they are used for dioramas with soft materials or for gluing rubber tyres when some flexibility in the joint is desired.

Plastic adhesives (like Tamiya or similar)

They work through chemical dissolution: they slightly melt the surfaces of polystyrene and molecularly weld them. The bond is practically invisible and very strong, but it only works with PS plastic (polystyrene). They are not suitable for resin, ABS, or metal. They are the standard choice for plastic model kits.

Gel or mounting paste adhesives

Useful for dioramas: they allow for gluing natural elements (sand, stones, moss) or textures onto prepared surfaces. Some have a dual function as a texturiser and adhesive.

Technical aspects we should know

Beyond the type of adhesive, there are technical concepts that are good to handle for effective work:

• Working time (open time): margin from application until the bond starts to set. The longer it is, the more margin for adjusting positions.
• Handling time: time until the piece can be moved without risk. Different from total curing.
• Total curing: time until maximum strength is reached. In epoxies, it can be 24-72 hours even though handling may be possible earlier.
• Shear strength: ability to withstand forces parallel to the bond. Crucial in joints subjected to vibration like those in slot racing.
• Peel resistance: ability to withstand perpendicular forces attempting to separate the bond from one end. Rigid epoxies are vulnerable here; contact adhesives or flexible ones resist better.
• Chemical compatibility: some adhesives attack painted surfaces, expanded polystyrene foams (white cork dissolves with many solvents), or soft plastics. Always verify before applying to a finished piece.

Another important aspect is surface preparation. A clean, dry, and slightly rough surface improves the adhesion of any adhesive. Degreasing with isopropyl alcohol before gluing is a simple habit that makes a real difference in the strength of the bond.

Practical tips for use, maintenance, and preservation

The application technique influences as much as the chosen product. Some tips we apply in the workshop:

• Less is more with cyanoacrylate. An excessive drop does not provide more strength: it becomes a problem. Cyanoacrylate works in a thin film; if there’s too much, it whitens and weakens.
• Prepare the epoxy mix accurately. The resin-hardener ratio is not indicative: if you alter it, curing is incomplete and final strength drops drastically. Use dispensers or measuring syringes.
• With contact adhesives, respect the waiting time. Most require that the film is dry to the touch before joining the surfaces. If you join them too soon, the strength is lower.
• Store cyanoacrylates in a cool, dry place. Heat and humidity accelerate their polymerisation inside the container. Storing them in the fridge (well sealed) significantly extends their shelf life.
• Clean the nozzle of cyanoacrylates after each use. A couple of seconds of cleaning prevent the cap from sealing and the container from becoming unusable.
• In slot racing, secure tyres with the appropriate adhesive. Some cyanoacrylates can attack rubber or make it rigid, affecting traction. There are specific products for tyre-rim bonding that maintain some flexibility.
• For dioramas, always test on a scrap of the material before applying to the final piece. Natural materials (sand, soil, dry moss) sometimes react unexpectedly with adhesives.

Common mistakes we should avoid

Most adhesive failures have easy solutions if we identify them in time:

• Using cyanoacrylate on expanded polystyrene foam. The solvent destroys it in seconds. For that material, use solvent-free adhesive (PVA or epoxy).
• Poorly mixing epoxy. If it remains sticky after the indicated curing time, it’s almost always a problem of ratio or incomplete mixing. There’s no solution once applied: it must be removed and repeated.
• Trying to glue dirty surfaces or those with release agent residues. Polyurethane resins often have residues of the factory release agent. Clean with alcohol before gluing.
• Using plastic adhesives on ABS or resin. They only work with polystyrene. They simply do not bond with other plastics.
• Not respecting curing times. Subjecting an epoxy joint to stress before total curing can compromise the entire strength, even if the piece seems secured.
• Applying too much adhesive expecting a better result. In almost all adhesives, excess is detrimental: it stains, dirties, and can weaken the bond due to excess material between surfaces.

Recommendations for beginners and advanced users

If you are starting

Medium viscosity gel cyanoacrylate is the most versatile adhesive to start with: it bonds plastic, resin, and metal with a fair margin of error. Combine it with an accelerator for better control of curing. For plastic model kits (polystyrene), a specific plastic adhesive like Tamiya’s will give you clean and invisible joints. With these two references, you cover 80% of the most common cases.

Avoid short curing epoxies in your first projects: the stress of mixing and quick adjustment can be frustrating. Start with one that has a 20-30 minute curing time if you need it.

If you already have experience

The advanced user usually has a small arsenal of adhesives for each case: liquid and gel cyanoacrylate, epoxy with different working times, contact adhesive for flexible materials, and if working in competitive slot racing, specific products for securing tyres and running gear components. The key is to know the limitations of each and not to improvise with critical materials.

In competitive slot racing, many preparers combine cyanoacrylate for quick fixes with structural epoxy for permanent or vibration-subjected joints. It’s also common to use screw lock products (like Loctite) to secure the chassis screws, although these are a separate category within the world of industrial adhesives.

Frequently asked questions about modelling and slot adhesives

What adhesive should I use to glue tyres in slot racing?

It depends on the tyre material and whether you are looking for a permanent or semi-permanent bond. Thin cyanoacrylate works well on urethane tyres on plastic or metal rims, but on softer rubbers, it can create a rigid zone that affects traction. For silicone or flexible rubber tyres, a contact adhesive or one specifically for slot tyres is more suitable.

Can I use cyanoacrylate on already painted pieces?

With caution. Excess cyanoacrylate can whiten the paint due to the fumes it emits while curing. Apply in small amounts and isolate the area if possible. It is generally safer on acrylic paints than on enamels.

What is the difference between 5-minute epoxy and 30-minute epoxy?

The 5-minute one hardens faster but usually has slightly less final strength and is more fragile against impacts. The 30-minute one gives more working time, cures more evenly, and generally offers better mechanical strength. For structural joints in slot or in resin pieces that will bear stress, we prefer the longer curing time one.

Does cyanoacrylate attack expanded polystyrene (white cork)?

Yes, it destroys it. The solvent in cyanoacrylate is incompatible with that material. To glue expanded polystyrene, use PVA (white glue) or solvent-free epoxy.

Why is my epoxy joint sticky?

It is almost always a mistake in the mixing ratio or incomplete mixing. Epoxy resins require exact proportions and thorough mixing (at least 2-3 minutes, scraping the walls of the container well). If one part does not catalyse, the bond will never reach its final strength.

How do I remove cyanoacrylate from a piece or my fingers?

Acetone is the most effective solvent, but it can attack plastics and paints. On fingers, acetone or specific cyanoacrylate solvents work well. On delicate pieces, you need to assess whether the risk of damaging the material is greater than the adhesive stain.

Is there a flexible adhesive for dioramas?

Yes. Contact adhesives and some modified PVA formulas offer flexibility once cured, which is useful for gluing organic materials or textures that may contract with changes in humidity.

Can I paint over cyanoacrylate?

Yes, once cured, cyanoacrylate accepts acrylic paint without issues. It’s advisable to lightly sand if the surface is uneven to ensure the paint adheres well. It also works with enamels, but always test in a non-visible area first.

What adhesive should I use to bond metal with plastic?

The two-component epoxy is the most robust option for joining different materials. Cyanoacrylate also works, but long-term strength is usually lower in metal-plastic joints subjected to vibration or temperature.

Do adhesives have an expiration date?

Yes. Cyanoacrylates are especially sensitive: under normal conditions, they last between 12 and 24 months once opened. Epoxy resins, if stored well (without moisture or extreme heat), last longer. After the expiration date or if the product has changed in consistency or colour, performance is not guaranteed.

Do I need to use a primer before gluing polyurethane resin?

Not a primer as such, but cleaning with isopropyl alcohol to remove factory release agent residues is essential, as this is the main cause of poor adhesion in resin pieces freshly removed from the mould. Additional light sanding further improves grip.

What cyanoacrylate accelerator do you recommend?

There are several valid brands on the market. Spray accelerators are convenient for large pieces; fine-tipped ones allow for more control in detailed work. The important thing is to use them sparingly: excessive accelerator can weaken the bond and generate an exothermic reaction that damages delicate pieces.