The cure speed of an adhesive is an important consideration for any countertop fabricator. A good understanding of cure speed will help to plan for complex part assemblies and maximize the throughput on the shop floor.
There are two main considerations when it comes to cure speed for an adhesive. Reference the TDS for the stated “open time” (sometimes referred to as “working time”) and “fixture time.”
The open (or working) time is the amount of time a fabricator has to join substrates together with the adhesive and apply clamps. Once the end of the open time is reached, the chemical reaction is at a point where any movement or disturbance of the bonded joint will have an adverse effect on the final bond strength.
The fixture time refers to the point where the bond has reached sufficient strength to allow the part to be moved, tooled, sanded, etc. It should be noted that the cure is not complete at the fixture time and the adhesive will continue to build bond strength as the reaction finishes.
The biggest variable that causes fabricators to have issues with cure speed is temperature. The information contained in the TDS is obtained in a controlled laboratory environment where the substrates, adhesives and air temperature are all kept at a specific constant. This never happens in a shop. For instance, introducing heat into the equation will cause the glue to cure faster. If it’s cold in the shop, or the sheet or slab of material being glued has been stored outside in a cooler climate, the fixture time is going to be extended. If it is too cold, the chemical reaction may not complete at all and the joint will have no strength.
Again, always refer to the TDS and follow the temperature guidelines for proper application and storage of the adhesive.