All paints consist of four (4) main ingredients - resins, additives, solvents and pigments.
Solvent is what makes the paint “wet”. After the paint is applied, the solvent evaporates off with time. Once all the solvent evaporates, the paint dries. What remains behind are the additives, pigments and resins.
The pigment is what gives the paint colour, whereas additives give the paint additional qualities which can include algae resistance, increased resistance to mould and fungus, self-cleaning effect, and etc. Finally, resins allow the paint to adhere to the surface. In the market, most resins are made up of silicone, acrylic or epoxy.
Indoor and Exterior Paints - SS150 and SS345
In most Developments, the paints for plastered surfaces are acrylic emulsion paint. These are water-based paint (i.e. the solvent is water) with acrylic resins. Acrylic emulsion paints generally have good adhesion to cement-based substrate. The two common acrylic emulsion paints in the market are paints in compliance with Singapore Standards SS345 and SS150.
SS345 is typically specified for use in outdoor/exterior environment whereas SS150 is used in an indoor environment. The key difference between these 2 systems is the paint’s ultraviolet resistance, algae resistance, mechanical properties, weathering durability and the fine-ness of the acrylic resin.
SS345 system contains additives that makes it resistant against common algae specie in Singapore. This gives the paint system its biocide quality. The SS345 system is also more viscous and contains finer pigments as compared with the SS150 system. These properties give the SS345 paint system better pigment dispersion and smoother paint texture, thereby reducing the probability of micro-organism retention in the paintworks. This explains why the SS345 paint system is more resistant to water and algae, and why it performs better under continuous exposure to weather (S.K. Roy et al, 1995)
For the reasons above, SS345 is typically specified for use in outdoor/ exterior environment whereas SS150 is used in an indoor environment. For most Developments, we have recommended the use of SS345 paint system for indoor environments as well – there are a couple of reasons for this. Firstly, for extended/longer warranty periods- most paint manufacturers give up to 7 years’ warranty against workmanship issues and paint defects for the SS345 paint system, but just 1 year for SS150. Secondly, most indoor environment in Condominiums and Commercial Developments are semi-exposed to the environment/weather. The use of SS345 paint system would prolong the life span of the paint system. The cost difference between the SS150 and SS345 paint system is not significant and hence, a material upgrade from SS150 to SS345 is justifiable.
Exterior Paint - SS345 vs SS500 paint system
Another paint system commonly used for exterior is paint system in compliance with SS500. The SS500 paint system is an acrylic elastomeric paint system. The elastomeric quality of the SS500 paint system gives it crack bridging and waterproofing qualities. The SS500 paint system is recommended for use in Developments with issues of seepages from exterior and/or Developments with extensive cracks along its external façade wall.
As discussed earlier, the elastomeric quality of the SS500 system makes it water impermeable, a quality that protects the building from seepages from the exterior. This same quality also means that any seepages from the interior will result in the formation of unsightly “blisters” on the painted surface. Another key disadvantage is that the Development would have to continue the use of SS500 system for the remainder of its lifespan. In a typical repainting exercise, the historical/old paint system is not stripped away unless the paint is peeling/deteriorated. As such, it is not advisable to paint back SS345 system once the SS500 system is used since the “elastomeric” coating cannot be completely removed away. Further, the warranty period for both systems are the same (7 years).
While the SS500 paint system can be considered “superior” to SS345 due to its crack-bridging and waterproofing qualities, it has its disadvantages too as described above. As such, the use of SS500 system is only recommended if the Development has severe extents of seepages from the exterior, or if there are extensive cracks along the building façade, or if the SS500 system has already been applied in the Development. Otherwise, the use of the conventional SS345 system is still recommended.
Paint systems used for metal and timber surfaces are typically based on Singapore Standard SS7, which is an enamel paint system. These are solvent- (or oil-) based paints, as opposed to an emulsion paint which is water-based. Such paints are used for timber and metal surfaces as these surfaces also tend to be sensitive to water. The enamel paint finishing is also typically glossier and easier to wash/clean/maintain. However, enamel paints are also harder to dry and produce odors. For this reason, enamel paints are not typically used for plastered surfaces.