Thompson’s water seal is a waterproof sealer that protects surfaces against water damage. But before it becomes waterproof, it needs to dry first. So, how long does it take for Thompson’s water seal to dry?
It takes Thompson’s water seal 2 hours to dry enough for a re-coat and 24-48 hours to fully dry. If you want to paint over it, you must wait at least 30 days.
According to the manufacturer, the level of humidity, room temperature, and substrate all determine its drying time. If you want it to dry faster, you should apply thin coats in the right drying conditions.
Dry Time Between Coats
It takes Thompson’s water seal 2 hours to dry between coats. This gives the existing coating enough time to harden to support a new coating, but it also prevents the coating to produce a glossy finish that repels the new coating.
You shouldn’t wait more than 2 hours to re-coat it as it will create a moisture-resistant layer that will prevent the new coating from sticking. So, re-coat it 2 hours after applying it.
Its dry time is also determined by the humidity levels, room temperature, and thickness of the coat. So, once the coating starts to become hard (or rigid) that’s when you must re-coat it.
Thompson’s Water Seal Cure Time
On average, a coat of Thompson’s water seal takes 21 days to cure while 2 coats take 30 days to cure. Only when the sealant has cured you are allowed to apply paint over it.
Its dry time depends on the air current and not heat. When the water seal is dry, it means that the solvent (or moisture) in the seal has been completely evaporated. So, when the seal is said to have cured, it means that the particles have become hard and waterproof.
For the sealer to cure, the particles need to be oxidized and this happens when it is exposed to air current (or oxygen). The oxidization process takes several days and is completed in about 30 days. So, you should leave it to cure for at least 30 days.
Only when the Thompson’s water seal has cured can it be top coated, painted, or exposed to moisture. If you expose it to high moisture content or paint before it has cured, then the finish will be ruined.
How To Speed Up the Drying Time of Thompson’s Water Seal?
Thompson’s water seal is a great sealant, but it has a slow dry time, Here’s how to speed it up:
1. Use A Hairdryer
Since the sealant dries through evaporation, you can increase the evaporation rate to make it dry faster. The idea is to expose the coating to increased heat using a hairdryer which will also increase the evaporation rate.
For this method, you’ll need these tools and supplies:
- A hairdryer
- A pair of gloves
- A face mask
Here is a guide for this method:
- Power or plug in the hairdryer.
- Set the temperature to medium.
- Move the hairdryer around the coating for 5 minutes.
- Repeat step 4 every 15 minutes for an hour.
- Leave the coating to dry completely.
Tip: You should only use this method immediately after applying Thompson’s water seal. Also, don’t dry the sealer completely with a hairdryer as doing this will cause the finish to dry too quickly and will offer little to no moisture protection this way.
2. Use Fans To Speed Up The Dry Time
If you expose the coating to increased air circulation, it will dry faster. The increased air circulation will speed up the evaporation and solidification of the sealer particles so it dries and cures faster.
Here is a guide for this method:
- Open all doors and windows for ventilation.
- Turn on the fans in the room.
- Open the air vents.
- Leave the fans on for hours till the sealer begins to dry.
Tip: Direct the air current from the fans directly at coating.
3. Apply Thin Coats
When you apply thin coats, the sealer will dry faster than when you apply thick coats. This is because the thinner the coating, the faster the solvent evaporates.
You can use a paint sprayer or bristled paintbrush to apply thin coats of the sealer. You shouldn’t thin or dilute the sealer for any reason. Diluting the sealer will ruin it.
4. Applying It In The Right Drying Conditions
According to Thompson’s water seal manufacturer, you must apply it when the room temperature is above 50 degrees Fahrenheit and when the substrate layer or undercoat is dry. If you apply it when the room temperature drops below 50 degrees Fahrenheit, it will take longer to dry because the temperature is not right.
Why Isn’t The Water Seal Drying?
The main reason the Thompson’s water seal won’t dry is if you apply too much of it. When this happens, the extra coats that you add will not stick or dry. Instead, they will gunk up the surface and remain sticky and wet.
After a while and due to the exposure to dirt and debris, the water seal will turn dark.
Here are other reasons why this happens:
1. Bad Drying Conditions
Thompson’s water seal has to be applied in temperatures above 50 degrees Fahrenheit and in a dry environment. If it is applied when the drying conditions and environment aren’t favorable, it will take longer to dry.
2. Water Exposure
If you expose the sealant finish to water too soon, it will get washed off. The sealant gets waterproof or resistant only after it has fully dried (cured). So, you must wait until it dries before it can protect the surface from water.
3. Sealed Surface
Thompson’s water sealer needs to bite into the surface to stick and dry properly. If there is an existing sealant, such as polyurethane or lacquer, on the surface, the water sealer wouldn’t bite into, stick, or dry on the surface. So, you need to remove the existing sealant first and then apply it.
4. You Waited Too Long For Recoat
Thompson’s water seal is a sealant and if you wait more than 2 hours before applying another coat, the first coat would have dried and sealed the surface making it impossible for the next coat to stick. Since the next coat doesn’t stick well, it won’t dry.
Tony is a professional painter and an author of DIY Geeks. Tony has completed over 1,000 painting projects for his clients. It's safe to say he knows what he Is talking about,