Hot Melt Glue Guns - Canadian Woodworking Magazine

Hot Melt Glue Guns

Glue sticks, and the glue guns they are used in, are most commonly associated with seasonal crafts and children’s projects, but if you take a closer look you’ll find they can be a useful accessory in the workshop. We normally look to woodworking glues when constructing our projects, balancing off the open time and conditions of use, to select the best adhesive for the task at hand. At first glance, hot melt glue may not seem all that useful, it doesn’t provide as strong a connection between two pieces as traditional wood glue and has a very short open time, but you can use this to your advantage.

The Gun
A glue gun is one of the simplest tools out there; it consists of a heater element, a channel to feed the glue sticks through the heater element, and a handle. In most cases they simply plug into a standard wall outlet and it takes about three minutes for the element to heat up enough to melt the solid glue sticks. When the glue flows easily from the tip, the gun has warmed sufficiently to begin working. For repairs on the road or away from a convenient power source look to one of the butane powered models such as the Master Appliance GG-100, galco.com. The GG-100 heats up in approximately the same amount of time as the electrical versions and will run continuously for two hours on a charge.

The guns on the market vary from basic models, available for less than $10.00, to professional models designed for more demanding applications, costing upwards of one hundred dollars. When selecting a gun for use in the shop, consider what you will be using it for as there can be considerable variation in control and comfort among the various models. The butane powered Master Appliance gun is the largest of the guns we use in our shop and it has the most reliable stand of the group; the lack of an electrical cord and the wide stance of the stand make this gun very stable when it is set down. On electrical models, the power cord usually enters the gun at the bottom of the handle with the fold-out stand located at the nozzle end. Unless the gun is equipped with a very flexible power cord (and they very rarely are), tension from the power cord will tend to cause the gun to be unsteady and tip easily when set down on the stand. As an additional safety precaution, wherever we use these tools we take along a 12 x 12 ceramic floor tile to serve as a non-flammable base to rest it on. A small compact gun is our favourite because of its size; it fits in the hand easily and can be used for a longer time without fatigue than the larger guns.

The Glue
The hot melt glue is a thermoplastic adhesive that ships in cylindrical rods or sticks which are inserted and heated in the gun until it melts. When the glue initially leaves the tip it is hot enough to blister and burn skin but it will solidify quickly as it cools. Depending on the glue sticks you purchase, hot melt glue has an open time from a few seconds to over a minute. This variation is greatly affected by your ambient temperature. You’ll be able to find glue sticks at most local hardware stores, and normally they have two or three different varieties to choose from. On a recent trip to the local Home Hardware store, I managed to find three different types. One was for wood, metal and plastic, another was for wood, metal, plastic, foam and paper, while the third was labelled heavy duty for woodworking projects. None of these packages contained any specific information on the glue and the performance one might expect.

Glue sticks made by J.E. Moser’s are also available from woodworker.com. They offer three versions as well, an economy clear stick that is suitable for porous fabrics with a working time of 30-45 seconds, a General Purpose Clear that is suitable for non-porous surfaces like glass and plastic and a High Performance Tan which is suitable for fabric, leather, and all woods with a working time of 20-30 seconds.

The Applications
The quick set and low strength properties of hot melt adhesive are of great value in the wood shop. When designing a new piece of furniture it can be difficult to visualize the final result, and jumping straight into the construction process can lead to costly mistakes. Using some shop scraps to quickly build a scale model of the project will quickly give you an idea of the volume and proportions of a piece. Hot melt glue is ideal for building these quick models (maquettes). You could also build a full size version of the project using Styrofoam and cardboard. This process will test out your design and further refine a project before beginning construction.

When installing trim on a cabinet, a piece of furniture or hanging trim in a house, use hot melt adhesive in combination with regular woodworking glue. Apply a thin film of glue to most of the surfaces to be joined leaving some bare wood exposed for the hot melt and when the glue has been spread out, place several drops of the hot melt on the open spaces and press the piece into place. Instead of using a brad nailer or 23 gauge pinner which will leave holes that will require filling, the hot melt will set up quickly holding the piece in place while the slower setting wood glue cures leaving an unmarked surface. Clamps with large flat faces like the Bessey K-Body are ideal for assembly and glue-ups. Their large clamping pads will not, under most circumstances, mark the work piece. Such clamps are expensive, so most woodworkers will likely have a larger assortment of F-clamps or pipe clamps to work with. However, the smaller bearing surface on these clamps often has a habit of marking softer material like pine and cedar if they are over-tightened. To distribute the force of the clamps over a larger area, cut up some MDF into squares and use some hot melt glue to affix them to the surfaces of the clamp. If you are gluing up a large panel with many clamps, use a long caul on either side, and use the hot melt adhesive to fasten the caul to the first and last clamps. It makes it much easier to proceed with the glue-up when you are not trying to juggle all of these sacrificial faces in addition to the clamps. When you are finished, a sharp tap with a hammer will remove the blocks from the clamps.

If you are building a piece that requires multiple parts, such as the corbels on an arts and crafts table, use the hot melt glue to fasten all of the blank pieces together and cut them all at once on the band saw. Use the adhesive sparingly or the pieces may not come together evenly. Also, separate them on completion with a hammer and chisel.

One of the ‘make or break’ moments in project construction is the mounting of the hardware, as it can be difficult to lay out the pieces for the best appearance. A drawer or door handle that looked perfectly fine when the drawer was sitting alone on the bench might look completely out of place when the doors and drawers are installed on the piece; the spacing may be wrong, throwing off the whole geometry of the piece. To refine the placement of hardware I use a combination of painter’s masking tape and hot melt adhesive. I begin by covering the back of the piece of hardware with some painter’s tape cut to size and then apply a small piece of painter’s tape to the spot on the piece where I think the hardware should be mounted. I then apply the hot melt to the hardware and press it into place to confirm the location. If everything looks fine I remove the hardware and drill the mounting holes. The extra step of using the painter’s tape is not entirely necessary as you could simply temporarily tack the hardware in place on the surface of the wood, but it does make it easy to remove the glued-on hardware without any risk of damage to the surface or leaving any residue behind.

Experiment with several positions before drilling holes

There is a type of glue stick for almost any application

Stack and hot-glue many pieces to save time in the shop

Protect your glue-ups from marring of metal clamps

Even More Uses
When working with small parts, use hot melt glue to fasten them to larger pieces to make machining them safer. Working with small pieces on power tools places your fingers in close proximity to the cutting edges, so keeping your fingers away from the cutting edges is the surest way to prevent accidental contact. When possible, shape your pieces while they are still part of a larger piece of material and sever them after the shaping is complete. If the piece cannot be machined as part of a larger piece, then use some hot melt glue to attach the small piece to something larger to make handling it safer.

Shop jigs can either be elaborate creations that will be used repeatedly or they can be quick and dirty assemblies that are needed for only one operation. For quick jigs that will only be used for one or two operations, use some hot melt glue to fasten the pieces together and then knock them apart when done. When building more elaborate jigs for the workshop, use hot melt glue to hold the pieces in place to confirm their position before fixing them in place permanently with glue and screws.

Once you’ve used a hot glue gun a few times in your shop you will realise the potential of this crafting tool. I use mine so often that I’ve build a custom holster under my bench to keep it close at hand.