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The complexity and simplicity of applying a water-based sealer

We are going to look more in-depth into our top of the range water-based sealer, G887 Sealer to understand how it works and when it can be used for maximum effect.

For starters, G887 Sealer is not technically hydrophobic, although if you use the right technique the water will bead up on the surface. A hydrophobic sealer has a chemically active surface which creates a strong beading effect. The G887 Sealer is simply a physical barrier. Water will sit up on the surface, as it would on any non-porous material, but may or may not bead.

G887 Sealer is a self-crosslinking polymer that builds a 3-dimensional matrix within the pores of the material being sealed. To get a proper seal and maximum protection all those pores need to be completely filled. These are microscopic pores, not the surface deviations you can see with your naked eye.

The most common issue we come across is that people don’t understand the complexity of sealers, therefore, they treat it like a topical sealer. That is, they will roll on one or two few light coats, regardless of the porosity, and expect it to be an impervious coating like paint.

For highly porous materials you will need lots of sealer product to properly fill the pores, this is why it is essential to do flood coats, to get the proper penetration. Therefore, on very porous materials we recommend priming with the W881 Sealer as it has a much larger particle size.

Using another complimentary sealer with a larger particle size is much more effective at filling larger pores and creates a much less porous surface to then apply another sealer with a smaller particle to get a good interlocking process.

Therefore, if you prime a porous surface with a sealer like W881 Sealer, you get a good foundation to apply more of the G887 Sealer which will form an interlocking matrix and will build up the resistance and integrity in and on the surface.

 However, if you do a water test and it looks like water is not sitting on the surface and going through, you can see this if the surface darkens, you may need to do another coat or two. Therefore, if you do four proper flood coats, instead of one or two, it should be well and truly sealed regardless of porosity.

 Another issue that can affect the performance of sealers is the presence of surfactants or detergents in the substrate that come up into solution when wetted. Such contaminants may interfere with the crosslinking of the product and thus you end up with a lot of individual polymer fragments rather than a continuous 3D matrix. In such instances, additional coats can usually rectify the issue.

However, we all know there can be problems! If there are problems with the sealing, these are a few questions you can ask:

  1. What material has it been applied to?
  2. Were the application instructions followed?
    1. Was the surface wet prior to application? If not it won’t penetrate properly into the pores and will therefore behave like a topical but without the bridging capability of larger polymers.
    2. Was it applied to the point of saturation (flood coat)? If it was rolled on just enough to dampen the surface the pores won’t get flooded
    3. What coverage rates did he get (m2/L total for all coats)? This combined with the material type will give an indication if sufficient product has been applied to get a proper seal
  3. How long after an application was the beading test done? The crosslinking process tightens over the course of the first couple of weeks, mostly in the first 72 hours.
  4. How long did it take for the test to darken? The matrix is breathable and therefore water can still slowly migrate through, then come back out again as it dries. If sealed properly this will take upwards of 15 minutes.

If any of this is confusing to you, or if the customer is someone who should already be familiar with the product application and there is still an issue please give Barefoot Concrete a call to discuss further.

A key to sealers is knowledge, and even then with everything involved in sealing, we can still be scratching our heads wondering why we are not getting the results or getting the results we are not looking for.

One of the finer details we need to understand regarding sealers is pore size. This is something most people struggle to conceptualise. So, to make it easier, and to visualize the difference, let’s consider the differences in size in descending order between a soccer ball, a tennis ball, and a golf ball.

If we were to fill a pit with soccer balls, it will take fewer balls but have bigger gaps and be more porous. However, if we were to fill the same pit with golf balls we would use thousands more and the matrix will be much tighter.

When we use this analogy with concrete, typical pores in concrete are 0.01 – 1 mm while the individual polymers in the G887 Sealer are about 30nm (0.000003mm). So, you need a lot of them to fill (or bridge) most pores.

Traditional acrylic sealers have individual polymers which are about 1000 times larger so they don’t even get into most concrete pores and are purely topical, they sit on top, whereas our polymers are penetrating into the concrete pores and forming a cross-linking matrix.

When compared to concrete, denser materials are a different story, for example, marble typically has pore sizes in the 2-200 nm range, it’s much less porous than concrete.

For the resurfacing system that Barefoot Concrete proposes for decorative concrete coatings, we recommend using the Shieldcoat system together with our polymer-based primer and sealers. These are Y863 Primer, W881 Sealer, B883 Sealer, and G887 Sealer. They are all concentrated polymers and complement the polymer-modified Shieldcoat system.

For a resurfacing application, what we usually recommend is priming the surface with Y863 Primer for good penetration, adhesion and moisture resistance. Then to apply the Shieldcoat product on top of the primer. Once the Shieldcoat has been applied seal it with one coat of the W881 Sealer. This primes the Shieldcoat coating and prepares the surface for the nano water-based sealers.

As the particle size is the largest of the sealers it creates the basis for the nano sealers to interlock and form a protective matrix through the self-crosslinking process. So you end up with good colour enhancement, good penetration into the surface, and good adhesion and resistance to water, dirt and oils etc.

Remember that applying different sealers on the same substrate will give a different result. The same principle applies when putting the same sealer on different substrates or coatings. The key is to be able to interpret all associated conditions and use the correct products, system and application process.

If we use the example above of using the Shiledcoat resurfacing system and sealing the coating with W881 Sealer, the surface becomes almost non-porous as it is sealed with larger particles that tend to sit on top.

Therefore, when applying the nano G887 Sealer, it integrates with the W881 Sealer, getting into the gaps, forming a cross-linking matrix and building up the surface protection, depending on the number of coats applied.

The way to test it is with a simple water test. Just pour a little water on the surface, if it beads up and does not darken the surface, you have sufficient coats. If it penetrates the surface, by slowly darkening the surface, you may want to apply another coat.

Therefore, two coats of G887 Sealer should be all you need. However, on raw concrete the G887 Sealer needs to do its own priming, that is, bridge a gap 1000s of times larger than itself, therefore, up to four coats may be required.

Therefore, in this instance, when you are using G887 Sealer without priming it with W881 Sealer, you could get much better efficiency if you put down a coat of the B883 Sealer given its larger polymer size before applying a final coat of G887 Sealer.

Again, first correctly interpret the associated conditions, as is if the surface you are sealing is porous enough, you can do a three-step process by priming the surface with W881 Sealer, as it has the largest particle size, then applying a coat of B883 Sealer, as it has a smaller particle size, and then applying a final coat or two of G887 Sealer, as it has the smallest particle size of our water-based sealer range.

As you can see from the example above, its knowledge and skill and experience and applying the correct system of application depending on the associated conditions. This only comes by experience!