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Explanation of epoxies

 

 

Disclaimer: Much of the information below is general in nature, non-specific to any particular brand accept where we specifically  refer to our own product. There are always exceptions to everything and no doubt someone might debate some points made below. However, in general, and to the best of our knowledge, the information below holds true and will make you more knowledgeable about epoxies.


1. Epoxy coatings are used because of their outstanding chemical resistance, durability, low porosity and strong bond strength. Better protective coatings are available but not as common.

2. Epoxies consist of a ‘resin base' and a ‘curing' agent. The two components are mixed in a certain ratio. A chemical reaction occurs between the two parts generating heat and hardening the mixture into an inert, hard ‘plastic'.

4. After the two epoxy parts are combined there is a working time (pot life) during which the epoxy can be applied or used. Generally the pot life will be anywhere from minutes to one hour or longer.

5. Epoxies will harden in minutes or hours, but complete cure (hardening) will generally take several days. Most epoxies will be suitably hard within a day or so, but may require more time to harden before the coating can be sanded.

6. In theory, a temperature change of 10 degrees C. will double or half the pot life and cure time of an epoxy. Higher temperatures will lower the viscosity (thin) the epoxy, but also reduce the working time a person has to apply the epoxy. Spreading out the mixed epoxy instead of keeping it concentrated in a bucket or container will extend the pot life.

7. Generally epoxies become too thick and cure too slowly to be applied at temperatures below 10 degree C.  During low temperature conditions, the curing time should be doubled or even tripled.

9. By nature, epoxies are hard and brittle. Additives can be added to epoxies that make them less brittle, but generally at the loss or reduction of other positive epoxy properties such as chemical resistance.  This why our complicated epoxy formulations consist of no less than 12 specially selected and tested ingredients to obtain the correct qualities.

10. Our specially formulated epoxy formulations have increased chemical resistance, increased temperature resistance, and enhance resistance to yellowing and UV damage.

11. Epoxies are expensive, but there are ways to ‘water down' epoxies with less expensive solvents and/or non-solvent thinners. These cheaper, diluted epoxies do not perform as well as the more expensive, unaltered epoxies. Diluted epoxies are especially common with floor epoxies where pricing pressures are especially strong. To a large degree you do ‘get what you pay for'. A common non-solvent thinner is a chemical known as nonyl phenol. This chemical is sometimes used in small amounts to make epoxy mixing ratios easy whole numbers. However, cheap epoxies may contain large amounts of this inexpensive chemical.  Our epoxies does not include any nonyl phenol! 

13. Other clues of cheap epoxies include ‘induction time' (after mixing the two components the mixture must sit for several minutes to ‘self cook' before being applied).  Another clue is crystallization of either part A or part B if left sitting for several months (like crystallized honey), simple heating will however dissolve the crystals.  Our epoxies can, and should be applied immediately after mixing the two components.

14. As epoxies cure, most epoxies ‘blush'. Blush is a waxy coating that forms in the surface of the curing epoxy due to moisture in the air.  Because nothing sticks to the waxy coating (including paint or additional layers of epoxy) it must be washed off or sanded off. Most epoxies blush to some degree but some of the very best epoxies do not.  Our epoxies offers minimum ‘blush’ and subsequent layers can easily be applied without the danger of blistering or peeling.  We do specify that completely dry coats should be sanded first to remove the risk of blush-residue and to break the gloss to further improve mechanical bond strength between layers.

15. The best time to recoat epoxy is within about 12 hours after the initial coat. Because epoxies take days to reach full cure, a second coat applied shortly after the first coat will partially fuse to the first coat rather than forming a simple mechanical bond.  We use the fusing of epoxy layers to establish a chemical bond between the Primer layer and Top layers, whilst allowing 24 hours between Top coats.

17. The difference between polyester (fiberglass) resins (commonly used in fiberglass boats) and epoxy resins: Polyester resins are much less expensive, have very strong fumes, are more porous than epoxy resins, and only sticks really well to itself.  For anti-blister marine or pool barrier coats, and bonding to wood, steel, etc.  epoxy resin is used and not polyester resin.

18. Thickening of epoxy van be achieved with many things, tiny glass spheres, known as micro-spheres or micro-balloons are commonly used. Besides thickening, their crushable nature makes sanding the hardened epoxy easier. On the downside, they work like tiny ball bearings, resulting is sagging and slumping. Another thickener is fumed silica which looks like fake snow. About 2 parts fumed silica with one part epoxy will produce a mixture similar in texture and thickness to petroleum jelly. Micro-spheres and fumed silica can be combined together.  Our epoxies used the highest quality fumed silica with additional additives to prevent sagging.  Epoxy coatings that are subject to sagging will result in the coating being thicker at the bottom of the walls than the top.  Our product has been formulated incorporating excellent anti-sagging capabilities with even thickness of the coat all-over the surface.  The anti-sagging quality is further improved by using quartz to stabilize our epoxy layers.

19. While epoxy floors are very common, for serious and demanding applications like submerged and chemical rich environments, our epoxy is mixed with quartz (sand) or aluminum oxide grains. Either way, the result is really a quartz or aluminum oxide layer, held in place with the epoxy. The quartz, is much more durable and wear resistant than the epoxy alone.  Quartz sand forms the one largest additive in our epoxy which offers excellent abrasive resistant qualities.  This means that the constant friction from moving water and the pool cleaner will not get through our tough epoxy layers.

20. How thick should an epoxy coating be? Thicker is not necessarily better. The paint on your office walls is probably 0.2mm thick. 0.5mm is considered a fairly thick industrial coating. 4 liters of epoxy applied at 0.5mm will cover 16 square meter. To be price competitive with the 0.5 mm coating on a cost per square meter basis, epoxies for thicker coatings would have to be very inexpensive. A primary way to reduce cost is to use low quality resins and lots of cheap fillers. As a result, the thicker coating may be inferior to the thinner, higher quality coating.  Our coating (consisting of 1 Primer and 3 Top layers) is approximitely 0.6-1mm thick and we don’t add fillers except for selected amounts of thickeners to enable the proper application by roller.

23. Fisheyes are areas on a painted surface where the coating literally pulls away for the substrate leaving a bare surface void or fisheye. Often fisheyes are caused by surface contaminants such as certain chemicals left in or on the pool surface. Applying a thick coat of epoxy over a contaminated fisheye surface will bury the fisheye but expect the coating to peel away in the future.  As a rule of thumb, always suspect some sort of surface contamination as the primary cause of fisheyeing, this is why we don’t acid-wash a pool like most of the applicators of pool epoxies.  We have learnt this the expensive way and rather grind surfaces clean before application.  We have perfected our methods and can now confident apply our epoxy on pool surfaces.  

24. Adding a bit of solvent to a solvent based or solvent-free epoxy is something that most manufacturers would not officially approve of and something that might not work with all epoxies. However, it can be done with the epoxies we deal with. Adding solvent to these epoxies will: 1) thin them out; 2) increase pot life; 3) allows them to flow off the brush/roller a bit more smoothly. No change is visible in the epoxy unless 12% or greater solvent is added. With that amount of solvent, the epoxies no longer cure with a glossy finish, our epoxies use the minimum quantity of solvents and will always have a glossy finish.  Our primer formulation has zero solvents and we do not compromise on bonding strength with the underlying substrate.

 

Preparing gunite/plaster pools for coating - recoating:

We believe that most of the coating problems experienced with traditional pool paints or epoxies originate from four main possible causes:

1) We have found that many epoxies used on swimming pools in the past, suffers from water and chemical absorption that will slowly weaken the paint layer over a period time, resulting in extensive chalking and progressive disintegration.

2) Moisture and minerals migrating from the concrete/plaster side of the coating and not from the water filled side.  This causes blisters or bubbles forming in the paint layer that may later result in open patches.

3) Concrete or plaster damage due to pool chemicals and the often low quality of the gunite, plaster etc. to start with.  This is sometimes visible when the paint layer might peel off, not due to inferior bonding, but due to loose and sandy surface material that is still sticking to the back of pieces that have peeled off.

4) Chloride (from bacteria control chemicals) or sulfate contamination (from pH control chemicals) that can cause blistering of new pool coatings in gunite/concrete, or even fiberglass and/or metal pools. These need to be removed by grinding the surface clean before application.  This is a process followed by very few applicators.

 

Conclusion:

We have overcome all these problems with a quality product and tested application methods that were developed and tested specific with swimming pools in mind and which offers a product solution that will ensure excellent penetration and adhesion, as well as good resistance to swimming pool chemicals and UV light.  This is one of the reasons that we will not combine our products into one formulation that doesn’t need a primer coat.  Using one type of epoxy to try and accomplish adhesion, penetration and chemical resistance means that we have to compromise on some of those qualities. 

Our base coat primer is specially developed with water resistance (from outside), penetration into concrete or plaster substrates, and excellent bonding qualities in mind.  Our top coat on the other hand was developed with bonding to the primer coat, a high quality gloss finish, thickness, abrasive resistance and chemical resistance in mind.  The combination of the two offers a durable product without compromising on quality.

 

 

 


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