How to Glue Ceramics
This guide takes you through the various options for gluing Ceramics to a number of different materials.
Ceramics are a type of material that is made from clay. They are very strong and durable, but they can also be very brittle. Although the can have a glaze that makes the surface appear waterproof, they're also quite porous which has a bearing on the choice of glue.
When gluing ceramics to other materials, it is important to use a strong adhesive; ceramics naturally don't bend and so it's the glue-joint that bears the strain when in use. This can lead to fractures at the original glue joint, or close to it where the glue has been absorbed into the fracture.
The most common adhesives used for this purpose are epoxy resin and cyanoacrylate - I'll go into each of these below.
Here's the table of contents for the guides below. I'll start with a general overview, then give advice on each of the materials that can, and can't, be effectively adhered to ceramics.
Bear in mind in each of these guides that I'm assuming that the glue joint is on a non-glazed section. If it's a glazed, ie non-porous, piece of ceramic then please read this guide on gluing glass. Glazed ceramic is essentially glass.
It is important to prepare both the ceramic and the other surface before gluing. If either surface is not properly prepared, the bond will not be as strong.
To prepare the ceramic surface, start by cleaning it with a mild soap and water. Then, roughen up the surface with sandpaper. This will help the glue to adhere better. If it's a broken (non-glazed) section, then it's more important to remove the surface residual.
In general, do the same to the other surface. The glues we'll be talking about all benefit from a bigger surface area to adhere to, and so roughing up will result in a better bond.
Gluing Ceramic to Ceramic
Things to Consider when Gluing Ceramic to Ceramic
The best glue to stick ceramic to ceramic depends on whether the bonding surfaces are glazed or not. If for example it's a broken cup, the non-glazed surfaces will be porous, whereas if it's sticking ceramic beads to a tile, both will be highly non-porous. Read the options below about what to do when.
The end look can be important, and some glues can dry in a hideous manner if they spill out of the edge of the bond. It can sometimes be fixed using a razor blade or sharp knife, but can't be generally wiped off after the first few seconds of applicaiton in some cases. Never use a solvent to get excess dried glue off - it way get the excess, but is likely to weaken the bond.
If the bond is for a plate or cup, then please do check whether it is food safe. Check out this blog post on food safety and glue.
Options for Gluing Ceramic to Wood
For ceramic to ceramic bonds where one surface is non-porous the best option is Superglue. It's more 'watery' than the alternative, and gives a good bond without the need for it to have a large surface area from the tiny gaps in a porous to porous bond. It's also suitable for that mind you, so can be used in either situation.
For porous to porous ceramic bonds then Epoxy is better than Superglue. It fills in those gaps and expands to fit them and ultimately gives a better bond. Be careful with the colour of the glue after mixing though - some change colour when mixed so in jobs that need a nice cosmetic finish can look ugly if there's excess.
Gluing Ceramic to Wood
Things to Consider when Gluing Ceramic to Wood
For an adhesive to work on a large area of ceramic, dry time is a significant factor. Some dry fast, but you will need one that gives you enough time to set everything in place before it begins to harden. Check the dry time on the product versus the area to be covered and the length of time you can isolate the area.
The type of wood also needs to be considered. For soft, porous wood like pine, the prep can be little more than cleaning with a solvent, and removing burrs. For hard woods like teak, the oil content becomes an issue. You'll need to work harder to make sure the surface is (temporarily at least) free from the natural oils that come out over time.
Ceramic is prone to sliding once in place initially, and chipping if the initial bond isn't secure and so it's worth taking the time to prep the surfaces fully.
Options for Gluing Ceramic to Wood
Epoxy resin is strong, but doesn't respond well to repeated shock loading. So it's a great choice for applications that have reasonable use, but a poor choice for floor tiles etc.. It also takes a considerable period of time to cure, and so the bond needs to have as little stress on it as possible for around 24 hours. High and low temperatures extends this time.
Polyurethane adhesive is a good all round option. It's initial curing time is relatively quick, but does give you around 10 minutes to replace and make good if the original placement wasn't exactly right. That's a bit of wiggle room, but not much, so it pays to pre-plan the whole area first.
Once cured, the bond is strong enough that it will likely be the wood or ceramic that breaks, not the bond, and it's flexible and so can take more shock loading than epoxy. It also expands in the gaps in the porous surface helping create that strong bond, is waterproof, and clear when it dries.
Silicone adhesive is the final option, but needs to be considered carefully. It's very flexible and so can take a lot of pounding. However, it really doesn't like sustained dampness or submersion, and so if there's a risk of that then this is not the right glue.
Gluing Ceramic to Metal
By metal, I referring to aluminium, brass, steal and stainless steel, all of which have the same advice. So long as it's a non or low reactive metal, the below will work. I've written a separate section for 'cosmetic' metals such as silver and gold, as there are different considerations there.
Things to Consider when Gluing Ceramic to Metal
It may be strange to hear, but metal is a very soft material. Just ask any engineer how a metal surface can easily be deformed by a careless but light blow! The flip side of that is that metal is pliable. By comparison, Ceramic is hard - it's what they make the nose cones of missiles out of - and brittle. So when pairing the surfaces in preparation, try to bring as much surface area of the two pieces into contact as possible, but when bending the metal to the ceramic, but careful not to fracture the ceramic.
It's difficult to make metal porous, and so there won't be much uptake of the adhesive into that surface. That limits the choice of glues but also makes it trickier to make a good bond if air gets trapped between the two surfaces. It's not such a problem if the ceramic side is the porous side, but certainly is a major factor if the ceramic surface is glazed, as you now have two non-porous surfaces that need to be bonded. There's no quick trick here - you just need to take your time, prep the surfaces well and work them back and forth (if possible) in the initial curing period.
Weight can also be a problem. Metal is heavy, and therefore difficult to keep in place. Add to that the non-porous, unyeilding surfaces, and it doesn't take much of a movement to put a gap between the two surfaces. If that happens and you don't notice it you'll end up having to pick off cured glue and starting again. Best to anticipate that movement and use a solid base or clamp - gravity is also good if you can stack it, but the point still stands that lateral movement can make the bond fail before it's even cured.
In some applications it's better to join the two pieces with a plastic bolt, but unless there's a hole there ready in the ceramic, I wouldn't consider that option.
Options for Gluing Ceramic to Metal
Cyanoacrylate Adhesive (Superglue/Krazy Glue)
This is a reasonable option for smaller applications, mostly limitted by the extremely short curing time and the cost. It will form an excellent bond with very high shear and tensile strength, and so can be considered to jobs where there may be force applied directly away from the bond, or at right angles.
However, the joint will be brittle, and so if there's a chance that there will be a leverage force on one part or the other (for example if it's a rod being glued to a base), then it's likely to fail.
Superglue also is prone to failing when in the pressence of solvents, or high and low temperatures. So it's really only for an indoor application when using with ceramic and metal.
Silicon glue is a good all-rounder here. It's a 'good enough' glue, but has the advantage of being inexpensive and easy to clear off the excess using a razor blade or knife.
The best formulation of Silicone Glue for gluing Ceramic to Metal is Plumbers' Goop. It's flexible, and therefore durable, resistant to most acids and chemicals found around the house, waterproof and paintable. Plumbers' Goop is available under a trade name of the family of adhesives known as "Goop". There are versions sold as All Purpose, Household, Marine, Outdoor and so on, but they're all essentially the same other than their ability to withstand UV light.
However, I wouldn't recommend using Goop when the end appearance is essential. It can get messy and is difficult to make right if it seeps out of the join.
Epoxy Resin can also be used to glue ceramic to metal, but the trick here is to be scrupulous in preparing the surfaces. You'll need to rough up the metal surface, ideally with a grinder or with 80 grit paper, or grit-blast the area. Then a thorough degreasing and cleaning is needed.
Epoxies are excellent for use in jobs where there's a void to fill. That is, where the match between the ceramic surface and metal surface isn't exact. However, watch out for the colour that the Epoxy mix will produce - some are clear but not all, so it's worth checking.
Gluing Ceramic to Plastic
The unruly partner in this combination is the plastic. Although it's a single term, it actually spans a wide variety of different types of plastics with different characteristics, and so a glue that may work on one may also eat away at another. By comparison, ceramic is far easier. Here's what to look out for.
Things to Consider when Gluing Ceramic to Plastic
It's a good idea to try to identify the type of plastic that's being used. There are usually markings as many if not all plastics now carry recycling marks. The mark looks like a triangle with arrows, and a number in the middle. In short you're trying to figure out whether it's considered a 'hard' or a 'flexible' plastic. Unfortunately, it's not always obvious, so I've gone into more detail about the different types of plastic in this blog post.
Depending on the application, both the plastic and ceramic may have very smooth surfaces. If this is the case make sure to rough up both sides - not just the plastic side - as the bond is only as strong as the smallest surface area between the two.
Consider where the bonding surface is going to be long term, as many of the glues formulated for plastic break down under strong UV light.
Options for Gluing Ceramic to Plastic
Cyanoacrylate Adhesive (Superglue/Krazy Glue)
For hard plastic, Cyanoacrylate Adhesive works particularly well because of the strong tensile and shear strenght. A two part cyanoacrylate adhesive works particularly well for applications such as sticking plastic to tiles in a shower. Just bear in mind the exceptionally fast curing time will mean you need to get it right first time, and the strong bond means it's real difficult to fix mistakes.
For flexible plastics, Polyurethane Adhesives are excellent. Once cured the bond is also flexible, and so will not shatter in normal use. They're also waterproof, so if it's for a bond to a tile for example, then it's a good choice. however, back to the plastic identification, it will eat away at hard plastic, as well as foam plastics like neoprene. As always, check the label on the formulation.
If the plastic to ceramic bond is intended for use under particularly strong loads, then the strongest adhesive to use is the acrylic based two component plastic bonders. There are a few out there, but this is the go-to for commercial applications. As well as being particularly strong, it's also resistant to almost anything - cleaning fluids, solvents, water of course. A permanent bond.