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How Strong is Strong Enough?

When selecting an adhesive for use on a specific project, there may be many from which to choose. It could be tempting to just select the adhesive that looks like it is the "best price". But if you choose your glue based solely on monetary cost, you could end up paying a "price" somewhere else. And even though you may not feel comfortable simply buying the most expensive stone glue available, you may not want to go with the lowest priced adhesive either. So the question then becomes, "how strong is strong enough?"

Bond Types and Strength

Not all types of bond perform the same. In fact, the type of material plays a role as well. For example, a chemical bond is the result of a chemical reaction between the adhesive and the substrate material. A chemical bond can be less effective on some materials than it is on others. For example, some materials can actually resist the chemical reaction. So, it should be noted, that just because an adhesive will work for one material, it does not mean that it will necessarily work for another type of material.

Another bond type that you may or may not be familiar with is the mechanical bond. As the name suggests, rather than being formed through a chemical process, this type of bond occurs as a result of mechanical interaction. A mechanical bond happens when the adhesive locks into place physically on a rough surface. This type of bond is made stronger by increasing the surface area to which the adhesive bonds. This is often done by roughing up the surfaces being bonded.

Tests Are a Good Guide

One of the pieces of information that is provided on a TDS is the adhesion force. As mentioned above, there are variances in the amount of force an adhesive can achieve with a given material. A good way to get an idea of a glue's strength is to simply check the TDS for the given adhesive on a specific material. Below you will see the TDS data for Glaxs, Mastidek, and StrongBond respectively. Each showing the adhesion force for the material listed.

Glaxs Technical Data (Typical Values)
Property Value
Viscosity cps 25°C 20 r.p.m (ASTM D2196) tixotropic liquid
Density at 25°C gr/cm³ 1.27
Aspect Colored Liquid
Ratio of use glue/hardener 2+1
Gel time (in bulk) at 25°C in min 3-5 min
Time for handling pieces 15-20 min
Working time suggested at 25°C in min 45-60 min
Minimun reaction temperature +1°C
Minimun temperature of use after hardening -25°C
Minimun temperature of use after hardening +60°C
Shelf life at 18-20°C 24 months
Adhesion force in MPa at 25°C on natural stone, diamond cut surface after 1 hour (ASTM D 4541)* 9.0 - 10.0
Adhesion force in MPa at 25°C on natural stone, diamond cut surface after 24 hours (ASTM D 4541)* 9.5 - 10.5
Adhesion force in MPa at 25°C on quartz, diamond cut surface after 1 hour (ASTM D 4541)* 9.0 - 10.0
Adhesion force in MPa at 25°C on quartz, diamond cut surface after 24 hours (ASTM D 4541)* 12.0 - 13.0
Adhesion force in MPa at 25°C on ceramic, diamond cut surface after 1 hour (ASTM D 4541)* 9.0 - 11.0
Adhesion force in MPa at 25°C on ceramic, diamond cut surface after 24 hours (ASTM D 4541)* 10.0 - 13.0
* The adhesion value depends on the material and on the type of cut.
Mastidek Typical Technical Data
Property Value
Viscosity cps 25°C 20 r.p.m.(ASTM D2196) Tixotropic Liquid
Density at 25°C gr/cm 3 1.27
Aspect Colored Liquid
Ratio of use glue/hardener 100+50
Gel time (in bulk) at 25° C in min 2 min-5 min
Time for handling pieces Approximately 15 min
Working time suggessted at 25°c in min Approx 45-60 min
Minimum reaction temperature +1°C
Minimum temperature of use after hardening -25°C
Maximum temperature of use after hardening +60°C
Shelf life at 25°C for the WA version 12 months
Adhesion Force in MPa at 25°C on DEKTON, diamond cut surface after 1 hour (ASTM D 4541) 11.0
Adhesion Force in MPa at 25°C on DEKTON, diamond cut surface after 30 days (ASTM D 4541) 12.9
StrongBond Technical Data
Property Value
Viscosity cps 25°C 20 r.p.m (ASTM D2196) tixotropic liquid
Density at 25°C gr/cm³ 1.27
Aspect Colored Liquid
Ratio of use glue/hardener 100+50
Gel time (in bulk) at 25°C in min 3min-5min
Time for handling pieces Aprox 15 min
Working time suggested at 25°C in min Aprox 45-60 min
Minimun reaction temperature +1°C
Minimun temperature of use after hardening -25°C
Maximun temperature of use after hardening +60°C
Shelf life at 25°C 6 months
Adhesion force in MPa at 25°C on LAPITEC, diamond cut surface after 1 hour (ASTM D 4541) 11.0
Adhesion force in MPa at 25°C on LAPITEC, diamond cut surface after 30 days (ASTM D 4541) 12.9

In conclusion, there are a variety of adhesives available for use on materials fabricators use. Since there are so many different materials that can be glued and different kinds of bond types, a simple way to determine if a glue is strong enough, is to check the technical data. However, for the results, performing an actual test on the material with the adhesive in question will give you the definitive answer.