How to select an adhesive

Top 6 rules to select the right adhesive for your project 

There are hundreds of different types of adhesives available in market and which one will work for your project is always a valid question to ask.  Often you would find there would be many different options available to do the job and narrowing down these options requires you to consider these top 6 rules:

The porosity of the materials

If you are bonding two substrates which are both smooth surfaces it would be best to use a chemically reactive adhesive in such cases such as an epoxy adhesive. The reason behind such kind of selection is when both the substrates are non- porous and if you use a solvent or water-based adhesive you will find essentially the solvent will remain trapped between surfaces and curing process will get affected. Hence a two-component epoxy adhesive will work best in such a scenario. When one of the materials to be bonded is porous it provides escape route for the solvent and helps the curing process.

Sensitivity of the surface

Most materials like wood, concrete, metals are very strong and usually will do not get affected by solvents present in some adhesives. In case you want to glue sensitive substrates such as paper, cardboard or polystyrene using solvent borne adhesives could possibly dissolve the substrate itself and it is not a good idea.  Such projects will demand a water base adhesive as it would be a safer choice for delicate surfaces. Moreover, water borne adhesives are easy to use, low VOC, cheaper and offer good spreading properties. Given the fact that they have many benefits they can be a high-performance alternate to solvent-borne adhesives.

Flexibility of materials

It is very obvious question to ask yourself if the surfaces you bonding are flexible or rigid. Thumb rule is that you need rigid glue for rigid surfaces and flexible glue for flexible surfaces.

Dimensional Stability

If the substrates are similar or have similar properties in terms of coefficients of thermal expansion it is easier to bond them. But when dissimilar substrates are to be bonded together usually the coefficient of thermal expansion of both surfaces(materials) varies. This means when two different materials expand and contract at different rates in winter or summer period there could be disaster. In such cases using a flexible adhesive to accommodate any stress or strain on glue joint is always a good idea. It’s just common sense that using a rigid glue in such cases would cause adhesive bond to break or delaminate in the event of contraction or expansion.

Setting time

Few adhesives have a quick grab property while most common type of adhesives available may require you to clamp both the parts together for up-to 48 hours as the glue cures. If you do not want to clamp surfaces together selecting a quick grab/fast grab adhesive which offers you adequate wet tack to align the parts together would be best choice.

Colour

Some projects specially where glass is one of the substrates gets involved require you to consider the colour of adhesive. Adhesives are available in wide range to colours and if you want bond line to be invisible you can select a clear adhesive. In some cases, one can find adhesives of similar colours as of the substrates such as a concrete adhesive is easy to find in light grey colour.