Commons problems when using sealants and preventing them
The materials used in the facade can be very varied in terms of composition, from glass and aluminum to natural stone and concrete, through insulation and exterior finishing systems (SATE), glass-reinforced concrete, reinforced plastic. with fiberglass and even coated fabrics. All of them, very different materials, with different characteristics and needs.
Using the wrong sealant can lead to compatibility problems, poor adhesion, and premature seal failure causing air and water ingress and all related problems. The cost of the sealant in relation to the cost of the facade is very small, so it is worth making the right decision and saving a lot of money.
PRIMER OR NOT PRIMER
Some materials always require a primer, others never need it, and others depend on the surfaces where you are going to work.
But, what is a primer and what is it for?
Primer is a precoat that is applied to the surface to be sealed to prepare it for further processing. It is a generally liquid product that does not provide a final finish, but only protects it and acts as a support for a better adhesion of the sealant
A big problem in the industry is that when they do not know whether to use primer or not, they choose to use it without carrying out a prior analysis of the materials involved. It is essential to ask or ask the manufacturer about this application because it is not always efficient, since not all primers work on all sealants and substrates, and instead of helping adhesion they can end up causing a failure in the joint
To avoid these cases, do a test before starting the job and make sure to test all the substrate materials involved, because you won't know what might happen next.
Most of the buildings move. These movements are generally due to possible settlements during the construction or post-construction period, due to sudden changes in temperature or adverse weather conditions or other natural phenomena such as earthquakes, etc.
This means that the joints that have been designed have to withstand said movements without causing any breakage or fissure, thus ensuring the perfect continuity and tightness of the façade or floor where they are placed.
To prevent this, it is best to try to treat it in the design phase, ensuring that the joints are optimally designed to allow a high degree of movement depending on the conditions and situation of the building.
If you don't have too much sealant on top of the backing, there won't be enough adhesive to handle the joint movement. Without the support rod, there will be too much material in the joint for it to stretch properly. If the joint moves and the sealant is too deep or too shallow, the sealant breaks.
LOSS OF PROPERTY: BUBBLES
It occurs mainly with polyurethanes, due to the humidity of the substrate, which is too high. Some polyurethane sealants, during the curing process, emit a gas that is trapped in the first skin formation of the sealant, generating a bubble.
Another possible cause is perforation of the joint bottom during installation. It is necessary to avoid this perforation and therefore it is best to use non-pointed tools to insert it into the joint.
To avoid this, do not puncture the backing material and do not install too much sealant into the joint.
Heat can also be the cause of the formation of these bubbles. If the support is too hot, the sealer that is at a lower temperature produces a “cooking” effect and can generate these bubbles.
LOSS OF PROPERTY: DOESN´T CURE
We know that whenever our polyurethane sealants are exposed to certain alcohols during cure, this causes inhibition of the sealant cure. Sealant does not fully cure or may cure, but will be softer than normal without achieving the required hardness of the material. We do not recommend the following solvents as cleaners: denatured alcohol, isopropyl alcohol, ethyl alcohol. When using solvent to remove possible contaminants from the surface of the substrate, we recommend that you use xylene or xylene. In any case, the use of primers is always recommended to ensure perfect adhesion to the substrate as well as improvement of the curing process.
LOSS OF PROPERTY: DISCOLORATION
Keep in mind that all sealants, paints and coatings will have some level of color degradation over time when exposed to UV rays. Softer earth colors tend to degrade less than brighter colors, such as high chromatic reds, greens and blues.