Gluing

Gluing is the primary way of joining parts in ship modeling. Yes, you can also solder, lash with thread, or nail parts together – but even then you may need glue. Below we’ll go through the main material combinations and the adhesives and gluing techniques that work best for them.

What to glue with what?

The main criterion for choosing a glue is, of course, the materials being joined. But it’s not the only one. I recommend also taking into account at least three more factors:

1. Planned finishing – will the glued part be painted, stained, coated with a decorative finish, etc.
2. Surface condition – are there traces of oil, wax, paint, or patina
3. How much stress the joint will bear – for example, will the glued part later be planed, sawn, milled, or turned on a lathe

It’s hard to cover every relevant factor in one short article, but this is enough to get started. Since I write these tutorials based only on my own personal experience, I’ll list the glues I’ve actually tested on my own models. They’re common enough that finding an equivalent won’t be a problem. I’ll call out any quirks of specific brands separately. In the table below, glues are listed from the most preferable and general-purpose to the least preferable and special-case options – so you search for the material combination from top to bottom, and the first match is the most suitable. If that option doesn’t work for you, move further down the table.

Example: gluing a 2 mm wooden dowel into a 2.2 mm hole drilled in a gunwale that had been coated with oil. The first three options won’t work, since it’s impossible to fully degrease the hole. That leaves option 4 – Zap CA Medium – or reaming the hole out to 3 mm and using a thick two-component epoxy – option 8.

Adhesive	What to glue	Notes
PVA-based glues, clear (Titebond II Transparent)	Wood-to-wood	When an invisible joint matters, a clear finish is planned (oil, varnish, wax, stain, or a combination), the part carries no significant load, and it will not be machined further except for final sanding
Aliphatic resin glues (Titebond II Premium, yellow)	Wood-to-wood	When an invisible joint isn’t critical, and painting or further machining (sawing, milling, turning) is planned
High-viscosity (thin) cyanoacrylate glues (ZAP CA Thin)	Wood, metal, or plastics in almost any combination (except plastics that don’t bond with cyanoacrylate), when the gap between the parts is minimal	Parts must be well degreased; wood and plastic should not be very porous. The glue can be applied after the parts are already positioned, since it easily wicks into the smallest gaps. This type of glue can also be used to “stabilize” wood – for example, before drilling a row of closely spaced holes in a thin strip (belaying pin rails, cleats, and similar parts)
Medium- and low-viscosity (thick) cyanoacrylate glues (ZAP CA Medium or Thick)	Wood, metal, or plastics in almost any combination (except plastics that don’t bond with cyanoacrylate), when the gap between the parts is minimal	Medium-viscosity glues like ZAP CA Medium suit most situations, including surfaces that couldn’t be perfectly degreased. Low-viscosity (thick) glue is used on porous materials and when larger gaps need to be filled.
Metal glue (UHU Metal)	Metal-to-metal, metal-to-wood, metal-to-plastic	When a fairly strong joint is needed that can withstand variable loads. For example, it can secure a cast metal part to the hull (deck)
Specialized glue for plastic and hard materials (UHU Hart)	Plastic and wood in any combination	When none of the glues above are suitable – for example, when even low-viscosity cyanoacrylate is too thin, or there’s a risk of it attacking the coating on a painted part.
Special fabric glue (UHU Textile)	Fabrics and threads in any combination	Making sails where sewing is impractical; gluing on boltropes; finishing edges.
Two-component epoxy glue	Wood, plastic, and metal in almost any combination	When exceptional joint strength is needed or a large gap must be filled. In the latter case, the resin can be mixed with a filler, such as sawdust or special microspheres.

Gluing techniques for different types of adhesives

Every glue has its own quirks, but a few general rules almost always apply:

1. Surfaces must be clean and dry
2. The surface must be degreased
3. Any decorative coatings should be removed from the surface where possible
4. Parts must fit each other well – no glue can substitute for careful fitting! A gap larger than 0.5 mm is a reason to pause before gluing and ask yourself: “Have I really finished the fitting?”

Next, we’ll discuss the specifics of each type of glue and the best gluing technique for it.

PVA-based glues

The glue is applied to one of the parts being joined. The layer should be thin but ideally without gaps. Within a few minutes after positioning, you can still adjust the parts relative to each other. Ideally, clamp the glued parts together with a clamp, a clip, a rubber band, or some other method. The parts will bond without clamping too, but the joint will be weaker. After positioning, wipe away excess glue – for example with a toothpick – before it dries.

Aliphatic resin glues

This is essentially a type of PVA, but with improved water resistance and joint strength (the glue line is actually stronger than the wood itself). This means parts glued correctly with this adhesive can later be machined – sawn, planed, milled, or turned on a lathe. However, getting a strong bond requires solid clamping. You can apply the glue with a slight excess and remove any surplus later while it’s still under the clamp – if you don’t, yellow residue marks will remain. Before further machining, let the parts dry for at least 24 hours.

Cyanoacrylate (CA) glues

All glues of this type have fairly high tensile strength but noticeably lower shear strength. Viscosity is determined by special additives and mainly affects curing speed and gap-filling ability. As a rule, the thicker the glue, the longer it takes to cure. Thin glue sets in under a minute. Chemically, the curing (polymerization) process is triggered by residual moisture, so caution is needed – this type of glue bonds a modeler’s fingers faster and better than the parts held in them. That’s why I recommend using applicators, and applying the thinnest glues to the seam only after the parts have already been joined. It’s also strictly forbidden to work in cotton gloves – the reaction accelerates sharply in the porous material, to the point of causing burns. I mostly use medium-viscosity glue, partly because the additives let it work even on surfaces that haven’t been perfectly degreased. I use thin glue mainly for impregnating (stabilizing) thin strips and veneer – afterwards they’re much easier to work with, without the risk of splitting. Thick glue, on the other hand, is for cases requiring a strong joint with a gap between the parts (important: in this case the gap should not exceed 0.5 mm – if it’s larger, it’s better to use a thick filled epoxy resin; but ideally you should avoid gaps larger than 0.5 mm altogether and use filler instead if the parts are hard to fit precisely).

Specialized glues

There are glues with a fairly narrow range of applications, but which perform excellently within that niche. From my own experience, I’d put two glues in this category: metal glue and fabric glue. More on each below.

Metal glue (UHU Metal)

The glue’s name is right there in the heading for a reason – we’re talking about one very specific product. Yes, metal bonds reasonably well with cyanoacrylate and epoxy, but what if you need to glue parts quickly and the joint has to withstand shock loads? That’s where UHU Metal comes to the rescue. The gluing technique is as follows:

– glue is applied to both surfaces

– the parts are left to air for 10-15 minutes

– after that, the parts are pressed together precisely and, importantly, firmly for a few seconds.

That’s it! Leave the joint for a couple of hours to fully develop its strength, and then move on with your plan.

Two things are important to know:

1. Once pressed together, the parts can no longer be adjusted
2. The glue doesn’t dry clear and is hard to remove, so precision matters when working with it.

Fabric glue (UHU Textile)

Fabric and thread can be glued with various adhesives – for example, PVA or even cyanoacrylate. But that only works if you don’t need the fabric to stay fabric-like. If you need the seam to stay flexible, resist yellowing, and be water-resistant, it’s better to use a special textile glue.

Technique specifics:

1. Before use, the glue needs to be mixed (if it’s in a tube, kneading the tube by hand for 1-2 minutes is enough)
2. It’s enough to apply the glue to one of the parts, then immediately press the second part in place and smooth the seam without letting the parts shift. Hold in place for 1-2 minutes
3. Let the glue set for 30 minutes, then press the seam with an iron at 130-150°C, or at whichever temperature is lower for the given fabric type.

Two-component epoxy resin glues

Let me say upfront – I don’t recommend this type of glue for static (display) modeling. It’s difficult to work with, has a limited working time, is hard to remove, and takes quite a while to cure. But these drawbacks come with real advantages – an extremely strong bond, the ability to glue almost any materials, and reliable gap-filling. For example, epoxy can permanently lock a 2 mm round blank into a 5 mm hole. Though, more often than not, that’s really a sign of a modeler’s mistake.

What should you pay attention to when choosing an epoxy? First and foremost, the stated curing (polymerization) time, as well as the so-called “working” time – the window during which the glue remains usable for application to parts. As a rule, the working time is much shorter than the polymerization time, which can range from 15 minutes to several days depending on the formulation. Second, the mixing ratio of resin to hardener. You need to follow the instructions strictly and remember that the ratio is usually given by weight, not by volume. Most manufacturers mark graduation lines on the resin and hardener bottles so that matching lines correspond to the correct ratio.

Third, viscosity. As a rule, it correlates with curing time (the shorter the curing time, the thicker the glue), but not always, so pay attention to this when buying. Too thin a glue will run out of the gap, while too thick a glue can be difficult to apply. It all depends on the specific case.

Another important factor is pour thickness. Epoxy curing is an exothermic reaction, and the shorter the curing time, the more intense that reaction is. So if you’re pouring a thick layer (for example, for a display base or diorama), read carefully what pour thickness is allowed per application. The greater the allowed thickness, the thinner the resin will be, and the longer it will take to cure (up to 72 hours). Ignoring this rule can damage both the casting itself and any surfaces in contact with the mold.

There’s also color, of course. But I always prefer clear glues, since they can easily be tinted with special dyes. And speaking of dyes – it’s worth mentioning fillers too. Adding, for example, wood dust from sanding or fine sawdust to the glue produces an excellent filler that’s very strong and suitable for further machining, such as on a lathe. There are also special fillers made of tiny plastic microspheres, but I rarely use those.

Where else is glue used?

Besides gluing parts together, glue is also used:

1. To secure servings/wolding on masts and yards – very carefully and in minimal amounts – CA
2. To seize thread ends against fraying during rigging work – CA
3. To secure knots, such as at the shrouds’ ratlines
4. To secure nails, eyebolts, or wire pieces imitating nails, and similar items
5. To stabilize strips and veneer before machining
6. To fill cracks and gaps – epoxy glue, possibly with filler
7. Many other cases where it’s appropriate.

I hope this material was useful. I’d be happy to hear your suggestions and comments through any convenient channel (https://www.glushkov-modelling.com/#social-hub)