Will Thompson's water seal prevent mold?

Author: Perry Daugherty  |  Last update: Saturday, February 14, 2026

Thompson's® WaterSeal® Wood Sealers help prevent mold and mildew from forming and curb the potential for rot to set into damp areas within the wood.

What is the problem with Thompson water seal?

Thompson's WaterSeal Waterproofer Plus Clear Wood Protector is intended to protect wood, as the name would indicate, but our testing produced dismal results. It does a very poor job of preventing black mold and UV graying, which are very harmful to the wood.

How many years does Thompson's Water Seal last?

On average, Thompson's water seal will last for about 5 years. Depending on the weather patterns in your area, this deck sealer might need your attention more often. In a rainy state, you might need a fresh coat of water seal for ultimate protection every 2-3 years.

What happens if it rains on Thompson Water Seal?

Thompson's Water Seal, offers superb weather protection for bricks, mortar, stone & concrete. Its advanced silicone micro emulsion soaks in deep to provide long lasting protection against rain damage.

Does Thompson's water seal stop damp?

Thompson's Water Seal uses a unique micro silicone emulsion to stop water penetration. Apply Water Seal directly onto damp surfaces to provide long lasting waterproof protection within hours.

Thompson’s water seal applied in cold weather solution 2323

Does Thompson Water Seal prevent mold?

Thompson's® WaterSeal® Wood Sealers help prevent mold and mildew from forming and curb the potential for rot to set into damp areas within the wood.

Does waterproofing stop rising damp?

Waterproofing Distinction: Damp proofing focuses on preventing ground moisture from rising through a building's walls or floor, typically using a damp-proof course. In contrast, waterproofing aims to block all forms of water, including vapour, withstand hydrostatic pressure, and combat soil moisture.

Can you use too much Thompson water seal?

“More is not better”. The situation that you have described is an over-application of Thompson's® WaterSeal® Clear Multi-Surface Waterproofer. The “excess” is due to the fact that Thompson's® WaterSeal® Clear Multi-Surface Waterproofer was unable to penetrate into the substrate.

How many coats of Thompson water seal are needed?

Only one coat of Thompson's® WaterSeal® Wood Sealer is necessary. A second coat can be added if more color is desired. Allow the first coat to dry approximately 2 hours. Second coat must be applied within 4 hours of initial application.

Can you put too much sealer on a deck?

Over coating

If too much sealer is applied, it cannot be absorbed into the wood. Wood is a fiber, and just like any other fiber it is capable of absorbing only so much. If you wet a sponge, and keep wetting it, eventually it will become oversaturated and the water will just pool on top until you squeeze it out.

What is the best outdoor wood sealer?

According to them, these are the nine most effective wood sealers:
  1. Thompson's Water Seal. ...
  2. Rainguard Premium Wood Sealer. ...
  3. DEFY Crystal Clear Sealer. ...
  4. Anchorseal 2. ...
  5. Roxil Wood Protection Cream. ...
  6. Eco-Advance Exterior Wood Waterproofer. ...
  7. Ready Seal Stain and Sealer for Wood. ...
  8. Pure Tung Oil Natural Wood Sealer.

Does Sherwin-Williams own Thompson's Water Seal?

Sherwin-Williams Co. said it will buy Thompson Minwax Holding Corp. from Forstmann Little & Co. for $830 million in cash, giving the largest maker of paints such as Dutch Boy the lead in household stains and sealers.

How often should I apply a Thompson water seal?

Thompson's WaterSeal includes a complete line of deck sealers and stains for protecting deck wood from moisture and sunlight. Applying a sealer and/or stain typically is recommended every one to three years, depending on the finishing product, deck use, weather conditions, and sun exposure.

What removes Thompson's water seal?

If you want to remove solid stains, you'll need to use Thompson's® WaterSeal® Maximum Strength Deck Stripper. This fast-acting formula will also take off difficult to remove transparent and semi-transparent deck stains, and clear waterproofers, while cleaning stains from dirt, mildew, algae and fungus.

What is the best water sealer for decks?

Best Deck Sealers for Clear, Maximum Protection
  • RONSEAL ULTIMATE PROTECTION DECKING OIL, 5 LITRES. ...
  • ROXIL WOOD PROTECTION CREAM, 3 LITRES. ...
  • EVERBUILD WOOD PRESERVER, 5 LITRES. ...
  • CUPRINOL WOOD PRESERVER, 5 LITRES. ...
  • BARRETTINE DECKING OIL, 5 LITRES.

What is the best applicator for Thompson's Water Seal?

You can use a pressure washer or a garden hose to clean the surface. If the surface is dirty or has mildew, you can use a Thompson Water Seal cleaner to clean it. Apply the water seal. You can apply Thompson Water Seal with a brush, roller, or sprayer.

How often should I reseal my deck?

Repeat Annually. It is generally recommended to seal your deck every year or two. Harsh winters or extremely hot summers can cause the sealant to wear away.

Do you stain before Thompson Water Seal?

Thompson's® WaterSeal® Wood Sealers can be applied to damp wood, so you only have to wait about two hours to begin applying stain.

What is the best deck stain?

2024's Top 15 Deck Stains: Revive and Safeguard Your Deck
  • Cabot Australian Timber Oil - Best Overall Deck Stain.
  • Ready Seal Natural Cedar - Best Budget Deck Stain.
  • Thompsons WaterSeal Advanced - Best Water-Based Deck Stain.
  • Sherwin-Williams SuperDeck - Best Oil-Based Deck Stain.

Is Thompson's water seal worth it?

This is a review of Thompson's Water Seal transparent and semi-transparent wood sealer, a water-based waterproofing product for exterior wood. Overall I do not recommend Thompson's Water Seal to my customers. There are many water-based products available that last longer and provide much better protection.

Can you apply a second coat of Thompson's water seal?

For best results ensure the surface is as dry as possible. Apply 2 coats using brush, roller and sprayer. The second coat should be applied when the first coat has soaked in to the surface.

Does damp proofing stop mold?

A damp proof course, or DPC, is a preventative measure usually injected into a properties walls to stop rising damp from spreading upwards into a property and causing damage, dry rot, wet rot, or black mould from setting in.

What is better, damp proofing or waterproofing?

Damp proofing prevents rising moisture from the soil. Waterproofing, on the other hand, stops any moisture and liquids from penetrating your structure. Additionally, waterproofing can withstand hydrostatic pressure, whereas damp proofing is not effective for water under pressure.

What are the disadvantages of waterproofing?

Cons Of Waterproofing
  • High Initial Costs. The upfront waterproofing costs can be substantial, especially if external methods are used. ...
  • Regular Maintenance May Be Required. ...
  • Temperature Sensitivity. ...
  • Potential For Incorrect Installation. ...
  • Reduced Breathability.

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