Thompson Water Seal Milky White – What’s Wrong?

Woodcrafts / By

If it’s your first time using Thompson Water Seal, you will probably not fuss over the milky white liquid seal in the can. But when it shows milky white spots a few days after application, your mind starts racing over the possibilities of sanding over your driveway or deck.

Many of our readers shared horror stories after applying the Thompson Water seal to their concrete driveway, wooden deck, and other surfaces. And even those avid users are surprised to open a can of seemingly frosted liquid seal when it should be transparent.

If you’re eager to know what to do, keep reading.

About Thompson Water Seal

Thompson is popular for waterproofing surfaces. Be it wood, concrete, or brick, Thompson Water Seal has developed an outstanding reputation in waterproofing. Since 1920, many construction companies trust their waterproofing products.

Many homeowners, not only in the construction field, trust Thompson water seal for many reasons.

  • Efficient in waterproofing
  • Applicable to many exterior surfaces
  • Proven formula

Why Does Thompson Water Seal Appear Milky White in Can?

So even though Thompson has a reliable formulation, they had to tweak their formula a bit to follow Environmental Protection Agency. Because of the regulation imposed on different states, manufacturers had to reduce the amount of Volatile Organic Compound (VOC).

VOCs are responsible for fusing polymer particles during the drying of water seals. After application, the water undergoes evaporation. And these polymer particles fuse, forming a translucent coating on the surface.

The water seals have to contain 100 grams of VOC per liter. To do this, they reformulated their formerly solvent-based water seals as water-based ones. If you see milky white liquid in the same old can of Thompson water seal (that used to be transparent), you are dealing with a water-based one.

Sometimes we open a can without the clear Thompson Water seal we know. A milky white liquid seal appears after opening the can. In this stage, the liquid has a gluish-like substance with a thick consistency. It can be pretty bothersome as some of the reports we received says they are viscous, like gum, to the point they have to follow the strokes with a roller or brush at once.

To understand the water-based seal better, know that water-based seals must mix two immiscible liquids like water and wax or additives. When you cannot technically blend them, they have to go through emulsification which results in milky white color.

While it looks this way, Thompson guarantees that the water-based seals are as effective as solvent-based ones. It may appear white but it eventually grays out and become transparent during the drying stage.

What Do You Need to Know about Water-based Seals?

If you are still not convinced about Thompson water-based waterproofer, here’s a quick rundown of the benefits you can enjoy.

  • Low VOC content
  • Dries quickly
  • Breathable
  • Low Odor
  • Non-flammable
  • UV-resistant
  • Durable

How to Spot a Thompson Water-Based Seal?

Still skeptical about the water-based solution?

You will never know that a Thompson water-based seal has milky white consistency until you opened the can. The packaging of a solvent-based water seal can is identical or similar to water-based ones. Many avid Thompson water seal users agitate over the milky white substance inside the can with the same label after opening them.

To clear things out, solvent-based Thompson Water Seal hasn’t phased out yet. If you received a water-based Thompson Water Seal, your region must have imposed regulations on the VOC content of water seals.

So how can you point out that you are buying the water-based waterproofer? If the label says clean with water, that is a water-based seal. If it says you can clean it with mineral spirits, it is a solvent-based waterproofer.

Why do Water-based Seals Appear Milky-White When Applied?

If you are still reading this, you are probably eager to learn how to make the water-based waterproofer work.

There are two scenarios for why water-based seals appear milky-white after application: whitening and blushing.

1) Whitening

Whitening is a condition happening after the application of a water-based seal. Frosted or milky white spots cover the surface a few days later. This phenomenon happens because of different reasons. And they all boil down to your manner of application.

2) Thick and over application

According to Tompson, you must apply only one coat. Otherwise, it will appear milky. When water tries to escape the surface, the seal should breathe and let the vapor escape. But if you apply too much coating, the vapor will trap into the seal, causing condensation between the surface and the seal. This condition will prevent the seal from bonding to the surface. The thick unbonded surface will now become the white spots you see on the surface.

3) Moisture presence

Wood, concrete, or brick are porous materials. You need to ensure they are clean and dry. Otherwise, the seal will not bond to the surface, adding a more pronounced milky white color. Additionally, areas with the most sun exposure and excess moisture or vapor will evaporate quickly, trap in the seal, and will not provide enough time to cure properly. Hence, the trapped moisture with the seal appears cloudy. For this reason, shaded areas without excess moisture will have transparent seals.

4) Weather

Weather highly affects the success of your waterproofing project.

Do not seal exterior surfaces when the weather forecast predicts incoming rainfall in the next 24 hours. The same goes before application day. Ensure the weather has been good for the past three days before applying. If it rained within 72 hours before the pre-determined application day, you must wait until it dries completely.

5) Blushing

Blushing is a type of whitening condition that happens within the seal. If there is excess moisture trapped within the film, it can disrupt proper curing and cause failure of coalescence or blending. If this happens, the primary ingredients– the water and the wax– will not emulsify as one coat. The coat will have an uneven coating appearance in milky white blotches.

When is it Safe to Use Thompson Water Seal?

So the problem now is not on the product itself. All you need to do is provide better conditions to apply the seal.

1) When the weather predicts no rain within 24 hours

You need at least 72 hours of no rain before and 24 hours after application. This condition ensures that the surface is dry for water-based seal or paint.

2) When the surface is free from dirt, grease, dust, mildew, and such

Ensure the surface is free from dirt, dust, mildew, mold, grease, and oil. For concrete and bricks, use concrete cleaner.

3) When the area achieves the required temperature

For Thompson water-based water seal, maintain about 40°F ambient and surface temperature 72 hours before and 48 hours after the application.

4) When the environment achieves humidity levels required

For exterior wood and concrete, the acceptable range of humidity levels is 30% to 70%. But ideally, you need 40% to 60% humidity levels. For bricks, humidity must be 30% to 50%, but 25% to 60% is acceptable.

5) If the surface passes the sprinkle test

The sprinkle test helps to see if the surface needs waterproofing. Pour water over the surface and see if it beads up. If the surface absorbs water, you need to seal it. It means the surface doesn’t have sealing properties anymore.

How to Use Thompson Water Seal Properly?

If you have prepared the surface properly, you can now apply a water seal on the surface. Make sure the surface is clean and not beading.

What Do You Need? You only need the water seal and choose how to apply it. You can use a roller, brush, or sprayer. You can also use a garden sprayer with a pump.

  • Pour the water seal into a clean container or the container of your sprayer.
  • Shake or stir the water seal properly before using. This measure ensures that you the products evenly.
  • Test on an inconspicuous area. Note that the liquid may appear white, but it will clear out as it cures.
  • Apply a generous amount using your brush, roller, or spray. An effective way to apply a water seal is by spraying and following with a brush. You need only one coat to dry for 48 hours. If you see a thicker coat, follow it up with an overlapping back-and-forth stroke. The least you want is to have them puddling in one area.
  • For multiple coats, wait 48 hours or more before applying a new coat.
  • Let the surface dry. The surface should dry within 48 hours. If must paint over the seal, wait at least 45 days before painting.

How to Correct Milky White Spots in Water Seals?

If you are not pleased with the milky white spots you see on your deck or driveway, you can still fix it with a power washer while still wet. But believe me, time will cure the seal, and the coat clears out eventually. You only need good weather to let it cure.

But if you still need to clear the spots, you can correct them with xylene. Xylene will re-emulsify the white spots, streaks, and cloudy appearance. However, only use it 24 to 48 hours after applying the seal.

Identify the problem area and use a siphon sprayer. Let it sit there for one to two minutes to let it relax and re-emulsify the white spots. Apply only on the area that your roller or brush can reach. Use a back-and-forth motion. Ensure that you are not leaving the surface with brush or roller patterns.

Final Thoughts

A milky white consistency in the Thompson Water seal is natural. This consistency is normal for water-based water seals. In reality, this version of the Thompson water seal is much safer than solvent-based because it complies with green standards.

Sometimes, you may see these seemingly cloudy appearances on the surface after application. Even if you see it a few days after, do not panic in horror. You can still correct it. But remember, nothing is better than proper surface preparation and maintaining the required temperature and humidity levels.

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