FREQUENTLY ASKED QUESTIONS
How do I calculate the amount of coating required?
Example: if thickness is 16 mils then coverage is 1604/16 = 100 sq.ft. per gallon. Divide area by coverage to get an estimate of consumption – remember, this is theory – always allow a little more for wastage and losses.
Note: the coverage calculation only works for solvent-free coatings like TFT – if the coating being used is solvent based this coverage is reduced.
Can I add solvent to a solvent-free TFT coating?
Note: Remember at all times that epoxy solvents bring with them health, flammability and odor problems. Avoid inhalation and ensure that there are no sources of ignition in the project.
What Surface Preparation is required?
What is the effect of temperature?
What is “Potlife”?
Why do “paints” contain solvents?
- Paint solvents are health hazards, air polluters, flammable and smelly.
- Solvent residues remain in the paint film long after application and can cause severe blistering upon immersion and cracking due to continued film shrinkage even months after application.
- Solvents are no longer cheap and contribute only costs to the final coating job.
How do solvent-free coatings work?
- Heat doesn’t smell! Ventilation requirements in enclosed spaces are much reduced.
- Heat begins to dissipate immediately after the coating leaves the spray gun. After reaching the relatively cool surface it is quickly lost to the “heat sink” and the coating recovers its gelled viscosity to prevent runs and drips.
- Blistering problems and shrinkage cracks caused by solvent residues are no longer a problem and the cured film is denser and more protective.
What is the effect of humidity during application and curing?
Typical TFT base and curing agent mixtures are totally compatible through all phases of curing as well as being extremely hydrophobic. Unlike mixtures susceptible to moisture attack they repel moisture and even cure with a glossy surface after application and curing underwater. Because of these attributes there is never a problem coating with TFT products under humid conditions.
When is the best time to coat concrete?
The second answer is that the best time of day for concrete coating is late in the afternoon when things are beginning to cool off. Prior to this there can be problems with bubbling from trapped internal air in the concrete which expands throughout the early day as the sun heats up concrete slabs. When the surface is suddenly covered by a layer of uncured coating this expanding air seeks to escape by blowing bubbles through the coating – usually coming out as streams through the same spots. As the concrete cools the opposite happens and coating is sucked into the concrete surface – which is a good thing.
How should concrete be prepared for coating?
When concrete cures it forms a thin and weak surface layer called “laitance” on its surface which is formed from cement and very fine aggregate. This layer is so weak that when a strong coating applied to it is stressed it will be the weak link which breaks resulting in detachment of the coating system. Obviously laitance has to be removed before coating.
Mechanical methods are by diamond grinding, open air/abrasive blasting or centrifugal shot blasting can all work well. Centrifugal blasting using “Blastrac” or similar equipment does a great job however requires a decent sized project because of its mob and demob costs.
Chemical methods involve etching with an acid –usually 10% hydrochloric, (or “Muriatic”), acid followed by neutralizing with soda ash and thorough rinsing.
This can work however it is messy and can cause severe stains in adjacent areas such as driveways. A sheetrocked garage can suffer sheetrock damage from accidental soaking. If acid etching is used make sure that the surface is properly neutralized and thoroughly dried after rinsing before coatings are applied.