Issue 5: Surface and Substrate Preparation

Surface and Substrate Preparation

Having the correct Surface Preparation can be the difference between success and failure in Coating adhesion

Polyurea coating has been called a revolutionary chemistry that can be applied down to -35˚ F and withstand water exposure almost immediately. As good as the technology is, however, the truth is that no coating chemistry can make up for an improperly prepared surface. Ask anyone in the industry, and they’ll tell you that most failures are a direct result of poor surface preparation.

In fact, in its infancy, polyurea was promoted as the coating that would cure on any substrate.  But many early polyurea jobs failed because the coating cured without sticking to the substrate.  The result was a catastrophic adhesion failure for the job and a public relations problem for the polyurea industry. The performance properties of a coating system don’t eliminate the need for the user to ensure that the coating system has something structurally sound and clean to which to adhere.

If a surface is contaminated with oil, for example, the oil must be removed. The substrate must not only have a surface or anchor profile to get good mechanical adhesion, but also have a level of cleanliness appropriate to the application and end use. Beware of the salesperson who tries to convince you that the product is tough enough to make up for an inadequately prepared anchor profile.

Also known as surface profile, the anchor profile is the topography of the surface to be coated.  If the anchor profile left by the surface preparation is too smooth, it allows for coating slippage, or creep, when the coating is exposed to lateral pressure. So be sure that there is an appropriate level of roughness for the coating to fill. The level of anchor profile required depends on the coating system used, the choice of primers, and other considerations that the specifier should consider. The graphic visually demonstrates the anchor profile.

Ask questions and get answers that make sense ahead of time to avoid having to backpedal and investigate a job failure later. Polyurea coating technology is coating chemistry. Protect yourself with the facts. At the end of the day, you are the one to whom your customer will either give, or not give, repeat business and referrals. It’s your reputation on the line.

Issue 4: Significance of Cross-link Density

The Significance of Cross-Link Density    

Cross-link density refers to the way polymer threads are woven together and the density or packing of those threads. The higher the cross-link density, the better the barrier-type properties of a coating system.

An example illustrating the cross-link densities of two different polyurea coating system formulas is chain link fence vs. chain mail armor. Both are made of metal, are woven together, and offer a certain level of protection. If a circus performer were to throw an ax at you, you could feel equally confident of your safety by standing behind either a section of chain link fence or a section of chain mail armor. In both cases, the molecule size of the ax cannot penetrate the cross-link density of your formula. However, if that same circus performer were to throw a razor-sharp 7” balanced knife at you, you would probably not feel the same level of confidence standing behind the fence as you would the armor. Why? Because the cross-link density of the armor doesn’t allow the small molecule knife to pass through. Which would you choose for protection, the chain mail or the chain link fence?

In comparing Polyurea coating systems, cross-link densities are not all the same. Although similar, the end results, and the level of protection offered, can be very different from one formula to another. By design, coatings with no solvents or volatile organic compounds (VOCs) of any kind (listed, exempt, or other) have the capacity of exhibiting the highest cross-link density.

Don’t be deceived or misled. The use of any solvent in a coating system is both a performance and safety concern. Look for materials which are designed for the specific needs of your project

Issue 3: The Truth About claims of No VOC

The Truth About Claims of No VOCs

 

Finished Basement with Glossy finish

 

The original definition of a Volatile Organic Compound (VOC) was any organic compound with a vapor pressure higher than 0.1 millimeter of mercury, allowing it to enter the atmosphere quickly and easily.  VOCs typically lower the viscosity, or thickness, of the coating chemicals and enable the chemicals to be more easily sprayed. Most solvents meet the original definition of a VOC–entering the atmosphere quickly and easily–but not all solvents are VOCs, something not commonly known

An exempt solvent is a solvent compound that by all characteristics is a VOC according to the original definition but has been exempted from the law for some reason.  Unscrupulous coating suppliers can incorporate either non-VOC solvents or even exempt solvents into their formulated products. By definition, they now have a non-VOC product. Some companies will sell a product labeled as Zero VOC that contains non-VOC solvent, but never disclose that information on the label.  Zero VOCs does not mean no solvents, and the product label may not tell the whole story.

By using a non-VOC solvent to disperse the resins, formulators can use much cheaper resin raw materials.  On the other hand, true 100% solids resin materials, while more expensive, have a low enough viscosity to be cold sprayed without the use of any type of recognized solvent.  Beware of the phrases Zero VOCs or No VOCs.  They do not automatically mean solvent-free or no solvents.

Investigate further into whether a coating, in fact, has no solvents, versus only no VOCs, by learning more about some of the solvents defined as “exempt solvents” in the United States.  These include:  Acetone, Methyl Acetate, Volatile methyl siloxanes, Parachlorobenzotrifluoride (PCBTF), Methylene chloride, and a wide range of chlorofluorocarbons.  You may find these listed either on a side panel of the packaging or on the Material Data Safety Sheet (MSDS).  When you request a MSDS from the product manufacturer, it should always be made available to you.  Some manufacturers provide this information on their websites

Issue 2: Solvent Vs. No Solvents

Solvent Vs. No Solvents 

Coatings that contain solvents or water are inherently more porous than coatings that are truly 100% solids.  With solvent or water in a coating system, the formulator must allow for that solvent or water to evaporate through the coating.  By design, the formulator must plan for enough space between the polymer threads of the coating to allow the solvent or water molecules to escape through the coating itself while it is drying or curing.

However, if there is enough space to allow the molecules to pass out, you should be concerned that there is also enough space for those same molecules to come back in. That coating may be unable to stop water or other contaminants from passing through the coating.  The way the polymer threads are woven together and the density or packing of those threads is called cross-link density. The higher the cross-link density, the better the barrier-type properties of a coating system.

When you apply a coating that has 50% solids and 50% water or solvent, you are paying for materials that will not help protect your surface.  This is because the solvents and/or water volatilize, or evaporate, out through the coating surface, leaving you with only half of the coating thickness that you have brushed or sprayed on.  Possessing only half of the thickness in applications that involve abrasion or wearing away of the coating means that you have only half of the protection, or half of the service life, possible with a coating that contains no solvents or water.

One additional benefit of having a 100% solids, no solvent or water coatings is that it can typically be applied at virtually any coating thickness. Additionally, a coating containing any solvent and/or water has significant limitations in its application thickness.  The coating formulator knows that the solvent and/or water must escape the coating film as the coating dries or cures, or it will bubble, blister, and peel.  So, if the applicator paints the coating on too thick and the solvent/water does not get through the coating film before the top of the coating sets up, the coating will fail.  Unfortunately, since coatings wear away through atmospheric abrasion, UV exposure, and other effects at a certain rate per year, a thin coating means that the coating will likely fail earlier than a thicker coating.  This leads to having to apply multiple coats to try to get longer service life.

 

 

Penetrating Vapor Barrier is used in Industrial Work too

The resins we use have been crucial in solving problems in Industrial as well as residential buildings and structures. We have solved a coating delamination problem in an industrial process tank in South America. They had tried three other solutions prior to using our materials.

The first ones failed within 9 months. Our is still going strong 3 years into service. We use what is most appropriate material for a given substrate, use and conditions. We have access to some of the best products in the world.

 

Commercial Concrete Tank being Sealed

Keene Home Expo April 13-15 2018 at Keene Ice 380 Marlboro Street Keene NH

Come See us at the Keene Home Expo, Keene Home Show in Booth 21

 

Keene Ice at 380 Marlboro St, Keene, NH 03431.

April 13-15 2018     Friday 2-8PM, Saturday 10-6 and Sunday 10-3.

Come see our other technologies including Foundation Repair, Vapor Barriers, Decorative coating options and roofing solutions as well as Waterproofing Products

Water beading on porous brick.    We can keep moisture out of where you live and work.

 

 

Issue 1 Open Time

Open Time

Open time (or working time) in the chemistry of two-component coatings is the elapsed time between when the two coating components are mixed together and when they have sufficiently reacted that they are no longer workable.  Gel time in high performance coatings is the elapsed time from when a coating is placed onto a surface until that coating can no longer be moved around.

Typically, pure polyurea coatings react very quickly.  Historically, they’ve been applied using high heat and high pressure spray equipment, with gel times typically in the three- to seven-second range.  The application equipment has a spray gun, the direct impingement gun, bringing the two components of the coating system together under very high pressure, forcing them to react with each other.  Frequently referred to as hot spray, it’s widely used in polyurethane spray foams and two-component coating systems like polyurea and polyurethane coatings.

However, the latest formulation techniques available today allow specific raw materials to be blended together, providing a much greater open time.  The longer open time enables the polyurea or polyurethane coating, or polyurethane spray foam, to be sprayed through a relatively inexpensive gun that contains a static mixer spray nozzle rather than a high-cost impingement spray gun.  This equipment is frequently referred to as cold spray.

The crucial point about open time is that the faster the coating gels, or sets up, the less able it is to flow into, and conform to, the landscape of the surface being coated (known as surface profile or anchor profile).

In discussions of coatings, you may hear references to the wet out properties of a coating product.  The property of wet out, or wetting out, of a coating is its ability to conform to all the surface profile—that is, fill in all the little valleys and crevices so that a good mechanical bond is obtained.  The graphic below demonstrates this point.

Everyone wants a fast cure product; but, if it cures too fast to conform to the surface profile, the risk is catastrophic adhesion failure.

WB Sealer Systems, LLC uses formations which have open times up to 20 minutes for successful application and installation. This provides efficient installation with superior properties in the finished coating.

11 Issues to consider regarding High Performance Coatings

Over the next 3 months we will be blogging  short informational posts to help people understand the issues they should be aware of and be knowledgeable about when working with installers of High performance Coatings, Primers and Sealers. WE know an informed customer is a better customers.

Please enjoy and comment as we begin posting.  We appreciate your input and comments.