Frequently Asked Questions
- Q: Where is the testing done?
- A: Each GemSeal® plant has its own on-site quality control lab, which performs tests to continually monitor the emulsion process and the product as it is being manufactured.
- Q: Is all sealer manufactured by GemSeal actually tested?
- A: Yes. In addition to periodic tests during manufacture, all material produced is quarantined, re-tested, and certified – before it is released to the customer.
- Q: Do you test raw materials?
- A: Yes. All incoming raw materials are tested for two things: to ensure uniform properties prior to their use in production, and to ensure that raw materials meet our stringent specifications. Tests are also performed to closely monitor each stage of the production process.
- Q: I hear about “solids content” being important. What is “percent solids”? How is it measured?
- A: All emulsion based pavement sealers contain water. Solids content is the relative weight content of the total product which is not water. Solids content is tested by weighing a sample of sealer before and after it is heated at a specified temperature and time to remove the water and other volatiles to determine the weight fraction of the remaining residue or ‘solids’.
- Q: What does solids content of a sealer concentrate mean to the contractor or property owner?
- A: The simple answer is that solids content is what you are paying for. This is a generally reliable index of sealer quality. The percent solids number should represent the relative content of functional ingredients in the base sealer formulation – not including added aggregate or non-functional fillers, which can increase the measured solids content artificially.
- Q: What is solids content of a sealer mix design? Why is it important?
- A: Solids content of a sealer mix design is generally interpreted as the solids component of the combined sealer concentrate, dilution water, and liquid additives. Mix design solids determines how much of the applied coating will remain as a cured film after the liquid evaporates during curing. Sand content of the mix is usually left out of this calculation, because traction aggregate in a mix is not part of the binder membrane, and contributes relatively little to the cured film thickness. Higher solids content in the sealer concentrate product translates to allowing higher water dilution in the applied mix design.
- Q: Can solids content be too high in a sealer mix design?
- A: Yes. Besides the higher job cost and potential problems that come with applying a thicker consistency mix, use of mix designs containing less than the manufacturer’s recommended water dilution (i.e. solids content too high) are generally not advisable. In some instances under-diluted or excessively rich mixes (especially in heavier applications) can result in drying and curing problems, even under ideal weather conditions.
- Q: What is ash content? Why is it tested?
- A: Simply stated, ash content measures the relative proportion of clays and other mineral components to asphalt or refined tar binder resin in a pavement sealer formulation. It is performed by placing a pre-weighed sample of dried sealer residue into a small laboratory furnace. The weight of the remaining ‘ash’ after all organic resins (like asphalt and tar) have been burned off represents the percent mineral content of the sample. The ash test results are used to verify that proportions of the pavement sealer formulation are correct and meet specifications. This protects the user from buying a poor-performing sealer with too much clay and too little binder resin.
- Q: What is viscosity? How is it measured?
- A: The basic definition of viscosity is a fluid’s resistance to flow. There are a many methods designed to measure viscosity, and almost as many viscosity units of measure as there are methods. Even for a single test method, some materials can exhibit different viscosities under different conditions. (Pavement sealer is one of these.) In the sealer industry, the most widely used apparatus to test product consistency is the ‘Brookfield Viscometer’, a laboratory device which measures viscosity in ‘centipoises’ units, (cP). [100 centipoises (cP) = 1 Poise (P)]. For the layman, a material with a higher viscosity feels thicker, and conversely, sealer with low viscosity feels thinner or flows more easily.
- Q: Is the viscosity of sealer concentrate important?
- A: As an indirect measure of other important properties, yes. We monitor viscosities incessantly during and after manufacture to detect viscosity changes, which could indicate subtle changes raw material properties, or deviations in the emulsion process. For the contractor, viscosity of the sealer concentrate is usually a good indicator of value. Higher viscosity = higher solids = greater value. Higher viscosity in the sealer concentrate product also (but not always) translates to allowing higher water dilution in the applied mix design.
- Q: What role does viscosity play in sealer quality and performance?
- A: Sealer viscosity, specifically viscosity of the diluted sealer mix design, can significantly influence the quality and even performance of a seal coat project in several ways. First, maintaining suspension of sand in the job mix tank and subsequent uniform sand distribution during application is dependent on proper mix viscosity. Secondly, application viscosity of the seal coat mix can also be a key factor in performance and durability of the seal coat project. If consistency of the applied mix is too thick, inadequate wetting and flow of the film into small voids of the pavement may weaken bonding and adhesion of the coating to the surface, leading to flaking or delamination. Conversely, if viscosity is low, and consistency of the mix is too thin and runny, applied material tends to drain off higher plateaus of the surface topography and sand particles into pavement voids and crevices, leaving less cured film of sealer on the higher surfaces where it also receives the most wear and abrasion. This characteristic can cause the appearance of early coating wear and poor customer satisfaction. One of the primary requirements in formulating a successful sealer mix design is to avoid either of these viscosity extremes.