Ceramic and Porcelain Glue – Guide for Repairing Ceramics

• Fine porcelain has a grain size of up to 0.05 mm and is usually coloured. It is mainly used as tableware, household ceramics or sanitary ceramics, i.e. washbasins and WC bowls.
• Coarse ceramics have a variable and usually non-uniform colouring and a coarser grain size. It is mainly used as a building ceramic, for example in the production of roof tiles, tiles and bricks.

In addition to the above-mentioned applications, ceramics are also used as stove tiles and technical components such as slide bearings. In electrical engineering, ceramics often serve as material for insulators.

In recent years, the industry has increasingly discovered ceramics as a material for itself. It is therefore not surprising that technical ceramics, also known as engineering or industrial ceramics, are used because of their positive material properties. These properties are specifically optimized by adding certain grain sizes or admixtures to the ceramic base material.

In the applications listed here, ceramics have even partially replaced metals as materials. Ceramics have a very high heat resistance and waterproofness.

Furthermore, the sintering temperatures under which the green bodies are fired vary. A green body fired at low temperatures can have completely different properties than one fired at high temperatures.

What Ceramic and Porcelain Can Be Bonded?

In principle, all objects made of porcelain or ceramics can be glued. You can also glue clay or earthenware. Today’s adhesives are so well developed that it is even possible to bond components made of ceramic with other materials.

When choosing the right adhesive, the main factors are the application and the size of the parts to be joined. The porosity of the material is also a question that must be answered in advance. Therefore, it makes a difference whether you want to glue an object made of earthenware or a plate made of porcelain, for example.

Fortunately, the adhesive properties of ceramics are generally very good, as this material has a high surface tension. Ceramics have this property in common with glass, which can also be bonded very well.

Overview: Bonding Different Materials with Ceramic and Porcelain

In the following we would like to give you a tabular overview of the most suitable ceramic adhesives, with which also different materials can be bonded with ceramics:

• The main challenge for the user in ceramic bonding is that the substrates are difficult to fix. For example, if you want to bond porcelain, it is difficult to fix the surfaces to be bonded with a screw clamp. Otherwise there is a risk of further breakage of the material. For this reason, a particularly fast-curing ceramic adhesive such as superglue is generally recommended. This is particularly helpful when many small fragments have to be joined together again. It bonds non-porous materials together particularly well.
• A 2-component epoxy resin adhesive has a significantly longer curing phase than a superglue, but the resulting adhesive bond is even more permanent and durable.
• Which ceramic adhesive you use depends mainly on what you want to bond. If something is broken and you want to glue a stoneware vase, for example, superglue is probably the better choice. However, if you want to bond ceramic components to another material, such as metal, it is better to use a two-component adhesive.
• Another question is the size of the area to be bonded, because the choice of adhesive also depends on this. For larger areas, a surface adhesive is best suited, while smaller areas, for example a broken vase, can be joined well with a small dosing syringe and the super glue. For the latter, it is recommended to apply the adhesive as thinly as possible.
• Apart from these things, a good ceramic adhesive should be transparent so that the bonded seam is as unobtrusive as possible. This is particularly important for visually attractive objects.

Instructions for Ceramic bonding

If you want to repair broken ceramics, follow our step-by-step instructions. In the following, we will explain to you how to proceed best when repairing porcelain.

For the ceramic bonding you need:

• A suitable ceramic adhesive, see above
• A paper clip or adhesive tape to fix the glued pieces
• A bowl lined with soft material, such as cotton wool
• A razor blade to remove dried up adhesive
• Acetone for removing not yet dried adhesive and for cleaning in advance
• A paper plate to mix the adhesive if it consists of two components and is not supplied in a double chamber cartridge
• Possibly suitable filling material to fill up the edges, e.g. epoxy filling material or a corresponding ceramic filler
• A cold glaze to glaze the filling material, or an appropriate repair paint stick
• Disposable gloves

Have all materials ready and put on disposable gloves. Now you can start with the surface preparation of the substrates.

Prepare the Surface

• To repair ceramics, you must start with an appropriate surface treatment. It is important that the edges to be bonded are clean and free from all grease, dirt and oil residues. To do this, you can first rinse the substrates with hot water, dry them well and then thoroughly clean the broken edges with acetone. Make sure to use disposable gloves, because even skin grease can affect the adhesive properties of the ceramic adhesive. Old adhesive residues should also be completely removed. This is best done with a scalpel if the residue is dry.
• Now you should first assemble the pieces to be glued together like a puzzle without using glue. This will give you a good overview of the different parts.

Gluing Process

• After surface cleaning, apply the ceramic adhesive according to the manufacturer’s instructions. Depending on the type of adhesive, the application varies. If it is a surface adhesive, you can apply it more generously. An adhesive that is used for small ceramic fragments should be applied very sparingly and thinly. Our ceramic glue instructions are based on several small fragments.
• Apply the adhesive sparingly on both sides. Use a small nozzle or a fine brush for this purpose.
• With solvent-based adhesives, the flash-off time must now be observed. Please read the manufacturer’s instructions.
• Then the substrates are pressed together firmly and fixed if necessary. For break-proof materials you can use screw clamps for this purpose. However, if you want to glue clay or ceramics, we recommend using adhesive tape.
• Now the padded container can be used, because you can store glued pieces in it until the ceramic adhesive has hardened. You can store the glued pieces in such a way that they can dry in peace without already exerting too much pressure on them. If in doubt, always let the adhesive dry a little longer than indicated.

Remove Visible Edges and Fill In

• After gluing, adhesive residues should be removed immediately so that no unsightly noses appear. Dried-in residues can be carefully removed again with a scalpel. We recommend that you wait until the ceramic adhesive has dried before removing it, and only then scrape it off. Although it is also possible to wipe it off directly with acetone, the danger here is that the ceramic surfaces become smudged. It is not always the case that the adhesive residue still adhering is noticed and this remains on the substrate.
• To achieve the most durable bond possible, allow the adhesive to dry for at least 24 hours, but preferably two days.
• If you have to glue wide cracks, but no longer have all the fragments, or if tiny splinters have been lost, you can either use an epoxy filler or purchase a ceramic repair kit. This contains putty and a repair paint stick, which you can use to fill in and overpaint the splintered areas.
• If you would like to fill up the edges with epoxy filler, clean them again with acetone or isopropanol beforehand. Now apply the epoxy filler to the crack and smooth it down. You can use a small spatula or a stick for this purpose. Make sure that the spaces between the cracks are filled completely. Now the filler must dry; this can take up to 36 hours at room temperature. If you want to accelerate this process, we recommend gentle drying in the oven for twelve hours at 40° Celsius.
• Once the compound has hardened, it can be sanded smooth and painted over.