How To Waterproof Plaster of Paris? [Procedure & Precautions]
Plaster of Paris, also known as gypsum, consists of fine powder made of calcium sulfate and hemihydrate. Plaster of Paris is known from ancient times and is most commonly used in casting molds, ornamental works, and orthopedics.
When plaster of Paris gets dried, it becomes porous and absorbs the moisture on the surface. So it is essential to seal the plaster of Paris by following any waterproofing method.
To protect the plaster of Paris from breaks & cracks and to gain the ability to withstand the moisture, a proper waterproofing method is essential.
What Happens to The Plaster of Paris When It Gets Wet?
Since plaster of Paris is a porous material, if the plaster of Paris gets wet, it absorbs the water on the surface and begins to expand. As the plaster expands, it can cause cracks and weaken the surface.
Since the plaster of Paris is extremely susceptible to humidity, it emits moisture when it becomes dry and absorbs moisture if it gets wet.
The plaster is breathable, and sustaining high humidity over time can weaken the surface of the plaster of Paris.
So it is mandatory to do humidity protection using waterproofing treatments.
How To Waterproof Plaster of Paris?
In this article, I will share three effective methods to waterproof the plaster of Paris on your own.
Below are 3 effective ways to waterproof the plaster of paris.
- Dulux Aquatech water block method
- Marine resin method
- Linseed oil method
1. Water Block Primer Method to Waterproof Plaster of Paris
The water block primer method is an ideal technique for your plaster of Paris and it provides quick results. You can also find the advantages of water block compounds here.
- Water Block compound is 100% acrylic coating material used in long-lasting waterproofing systems since it produces an elastic film by blocking the water penetration.
- Water Block primer can also be used on damp walls, roofing, and exterior walls and protects against UV rays.
- It provides resistance to efflorescence, alkali attack and aids in preventing cracks on the surface.
- This primer withstands extreme temperatures and protects the surface from fungus and mold growth.
- It effectively seals the moisture on the surface due to its high-density characteristics.
- Water block primer formulated with hydro-breathe technology creates a water-resistant layer and can be used in greater water exposure areas such as water tanks, swimming pools and more.
Required Items
- KILZ primer
- Shellac/ waterproofing sealant
- Paint
- Paintbrush or spray gun
- Containers
Procedure [Step by Step]
1. Prepare the workspace
- Place sheets on the floor to prepare the workspace.
- Also, clean the plaster of the Paris surface from dirt and dust particles.
- Ensure there is no crack on the surface, or this will lead to improper waterproofing.
2. Apply water block
- Once the plaster of Paris is clean and dry, coat the plaster of Paris with the Dulux Aquatech water block covering the entire surface.
- Let the plaster of Paris (POP) dry for 15-20 minutes.
- Then coat the second layer of the water block on the POP surface.
- Now, wait until the plaster of Paris gets dry for 15 more minutes.
3. Apply Paint
- You can paint the plaster of Paris in desired paint colors.
- Let the paint gets dry completely for 2-3 hours.
4. Apply Shellac
- You can use shellac or some waterproofing sealant over the paint to ensure water protection for your plaster of Paris.
- The sealant will get dry quickly, and your plaster of Paris will be ready for your use.
Precautions
- Always prefer outdoor space to perform this method.
- Also, take necessary precautions by wearing gloves and mask while waterproofing, since the chemical ingredients cause health hazards.
Time
While the application process takes a minimum time of 10-15 minutes, the overall drying process can take up to 24 hours.
The total processing time is around 24 hours.
Cost
You can find the approximate cost for the required material:
- KILZ primer– $24
- Shellac – $18
- Paint – $16
- Paintbrush – $6
The overall cost for this method will be around $65.
2. How to Waterproof Plaster of Paris Using Marine Resin?
If you are looking for an easy waterproofing technique, then this method is for you.
The Marine resin has low viscosity and penetrates the surface, and totally seals it. It is resistant to cracks and is durable. Also, the marine resin has high impact resistance.
The marine resin can be applied and cured underwater. Also, the application is also very easy.
The resin has high resistant properties against water and other chemical solvents. And it does not shrink due to aging.
This type of resin provides UV resistance and offers a strong bond on the surface. It also contains less toxic hardeners and has a longer shelf life.
Required materials
- Marine Resin
- Paint
- Shellac or waterproofing sealant
- Paint brush
- Containers
Procedure [Step by Step]
1. Prepare the workspace
- Place sheets on the floor to prepare the workspace.
- Also, clean the plaster of the Paris surface from dirt and dust particles.
- If there is a crack on the surface, you need to fill the cracks-using setting-joint compounds and then proceed with any waterproofing methods.
2. Apply resin
- Once the plaster of Paris is clean and dry, coat the plaster of Paris with the marine resin, covering the entire surface.
- Let the plaster of Paris (POP) dry for 15-20 minutes.
- Then, coat the second layer of the resin on the POP surface.
- Now, wait until the plaster of Paris gets dry for 15 more minutes.
3. Apply paint
- You can paint the plaster of Paris in desired paint colors.
- Let the paint gets dry completely for 5-6 hours.
4. Apply shellac
- You can use shellac or some waterproofing sealant over the paint to ensure water protection for your plaster of Paris.
- The sealant will get dry quickly, and your plaster of Paris will be ready for your use.
Precautions
- The fumes from the resin can irritate, so make sure you wear a mask.
- Always prefer a nice ventilated place to perform this waterproofing method.
- Also, wear gloves and goggles to protect the hands and eyes while mixing resin process, since it can cause skin allergies.
Time
While the application process takes a minimum time of 10-15 minutes, the overall drying process can take up to 24 hours.
The total processing time is around 24 hours.
Cost
The approximate cost of material:
- Marine Resin – $92
- Shellac – $18
- Paint – $16
- Paintbrush – $6
The overall cost for this method will be around $135.
3. How to Waterproof Plaster of Paris Using Linseed Oil?
This waterproofing method provides high-quality results since linseed oil has various advantages.
This method uses Linseed oil, tung oil and oil paints to waterproof the plaster of Paris to reap the maximum benefits.
Tung oil is known for its water-resistant properties and has been used for centuries. It also protects the surface from mold and mildew up to a certain extent.
And, the linseed oil penetrates the surface and seals the cracks and gaps. Linseed oil has a water repellent nature and protects the surface from water damage.
The oil paint applied on the plaster over the linseed oil act as an extra water-resistant layer, and it makes the product sustainable for a longer life span.
Required Items
- Linseed oil
- Tung oil
- Oil paint
- Paintbrush
- Containers
Procedure [Step by Step]
1. Prepare the ingredients
- Make sure the plaster is completely dry without any dirt and old paints.
- Take a container and mix the tung oil and linseed oil (1:1 ratio).
2. Apply linseed oil
- Using a brush apply the linseed oil and tung oil mixture all over the plaster.
- Then let the plaster of Paris dry for 1 hour.
3. Apply oil paint
- You can use any oil paint over the linseed oil coating on the plaster of Paris. Apply thin coats of oil paint all over the plaster.
- Let the paint on the plaster gets dry completely.
- Once it gets dry, apply a second coating of paint on the plaster.
4. Dry
- Let the plaster gets completely dry for 2-3 days.
- The ideal waterproofed plaster of Paris gets ready for use after drying.
Precautions
- Linseed oil is extremely flammable and can cause immediate combustion, so perform this method in a dry place and under moderate weather conditions.
- Store the linseed oil in the original container in a dry place away from direct sunlight.
Time
While the application process takes time up to 30 minutes, the overall drying process can take up to 3 days.
The total processing time is around 72 hours.
Cost
The approximate cost for the required items:
- Linseed oil- $16
- Tung oil – $19
- Oil Paint – $20
- Paintbrush – $6
The overall cost for this method will be around $60.
Final Comments:
Plaster of Paris is used in various products, from casting molds, statues, decorative materials to sealing bones.
So it is crucial to waterproof the plaster to avoid breaks and cracks and to enhance the durability.
You can achieve great results by following the waterproof methods mentioned in this article. And you will be happy witnessing the results.
