November 3, 2023
Are you planning to reseal your concrete surface, but unsure of how to remove the old sealer first?
Don't worry, you're not alone. Removing concrete sealers can be a daunting task, but with the right knowledge and tools, you can do it yourself and prepare your surface for resealing.
In this DIY guide, we will take you through the step-by-step process of removing concrete sealers, including tips on identifying the type of sealer, using the right chemicals and tools, and preparing your surface for a new sealer application.
Whether you're a DIY enthusiast or a homeowner looking to save money on contractor fees, this guide is for you.
So let's get started on removing those old sealers and preparing your concrete surface for a fresh new look.
First,to remove a concrete sealer accurately, you need to determine the type of sealer that was initially applied.
How to test if concrete is sealed with a water-based or solvent-based sealer:
To see whether a concrete surface was sealed with a water-based or solvent-based sealer, apply a small amount of Xylene on an area that still has the previous sealer coating.
Let it sit for 20 seconds, wipe up any excess, then wearing rubber gloves touch the area.
If it feels tacky or sticky, then the surface was sealed with a solvent-based sealer. Conversely, if it doesn't feel tacky or sticky, then the surface was sealed with a water-based sealer.
The three most popular methods for removing concrete sealers are using a chemical stripper, pressure washing, or by grinding / sanding .
All three methods have some advantages and disadvantages, and the choice between the three will depend on the type of sealer and the condition of the concrete surface.
A chemical stripper is a solvent-based product that's designed to break down and dissolve the sealer on the concrete surface.
The stripper is applied to the surface, left to sit for a certain amount of time, and then removed using a scraper or pressure washer.
The advantages of using a chemical stripper are that it can be used on all types of sealers and is effective for removing stubborn, deeply penetrated sealers.
However, chemical strippers are typically more expensive, kind of messy, and may require multiple applications, making the process tedious and more time-consuming.
Here are the steps to using a chemical stripper:
By using a pressure washer, you can remove water based and some solvent based sealers from the concrete surface by blasting away the sealer.
The advantages of using a pressure washer are that it's usually faster and less expensive than using a chemical stripper.
However, it may not be as effective at removing deeply penetrated, and thicker concrete sealers.
Here are the steps to using a pressure washer:
Caution: Don't get the tip of the wand too close to the surface of the concrete as it may damage the concrete.
Mechanical methods can also be used for removing concrete sealers, but they are less popular than chemical strippers or pressure washers.
Mechanical methods involve using a walk behind or hand held grinder to physically grind or sand away the sealer from the concrete surface.
The advantages of using mechanical methods are that they are better at removing thicker epoxies or stubborn sealers and can also be used for preparing the surface for resealing.
However, mechanical methods can be time-consuming and can cause damage to the concrete if they're not used correctly.
Here are the steps to using a mechanical method:
When you're removing concrete sealers, paint, latex, enamel, epoxy, and polyurethanes from concrete there are three basic types of chemical strippers.
I'm not a big fan of the caustic strippers, but I do have recommendations for the biodegradable and solvent based sealer removers.
Biodegradable strippers are made from natural plant material. They are much safer for you and the environment than other chemical strippers.
The active ingredients found in biodegradable strippers are typically acids or esters derived from plants. Common plant sources include pine oil, corn sugars, citric acid and soy oil.
They usually take longer and may require more applications than some of the other chemical strippers but are easier to use, have less odor, are safer for the environment, and clean up & disposal of the by product is usually easier.
The best, 100% biodegradable, concrete cleaner - paint stripper- adhesive remover that I have used is Novion Universal Concrete Cleaner.
This concrete sealer remover is non-toxic, non-corrosive, and non-hazardous to you, your pets, and your plants.
Another good biodegradable sealer remover is Nock-Off by DecoCRETE Supply Co.
Solvent based strippers are the most common types of strippers used when removing concrete sealers. They usually work faster and you don't have to use as much product as other strippers.
Look for ones that contain the chemical Methylene-chloride. This is the most popular and will remove most all types of sealers from concrete.
Other types of solvent strippers include N-methylpyrrolidone (NMP), dibasic esters (DBEs) and combinations of Xlyene, acetone, alcohol and toluene.
Solvent strippers only work if you keep the surface wet, don't let the stripper dry out or evaporate.
You may have to re-wet the surface with the stripper a couple of times before you can remove the sealer.
Most solvent based strippers are aggressive enough to remove almost all types of coatings and sealers from concrete.
Common resins used in sealers like acrylic, epoxy, polyurethane, polyaspartic and polyurea are no match for a good solvent based chemical concrete stripper.
For safety: Keep in mind solvent based strippers are very flammable. They can cause severe skin irritation breathing the fumes over long periods of time could cause liver problems.
Always wear a mask and make sure there is good ventilation.
The solvent based stripper I use to remove paint and sealers from concrete is Klean Strip Xylene.
It penetrates through the paint/sealer and bubbles it off for easy removal, far better than any other stripper I have used.
Caustic chemical strippers are made from powerful alkaline chemicals. The high pH of the alkaline causes the break down of the sealer, allowing for moderate to easy removal from the surface of the concrete.
Caustic strippers are a good for removing latex, alkyds or enamel paints from concrete.
They are not a good choice for removing acrylic concrete sealer, epoxy, polyurethane, or polyaspartic coatings because these coatings have good chemical resistance to caustic chemicals.
The temperature should be above 50 degrees and plan on applying quite a few times to completely remove the coating.
One advantage to using a caustic stripper is it's less harmful and easier to handle than solvent-based strippers.
Once the stripper has done its job, a light pressure wash and neutralizing rinse is required to remove the coating and any remaining stripper to prepare the concrete for the next process.
Make sure to dispose of the waste material properly, as caustic strippers tend to stay active and can react with other chemicals even after they are removed from the concrete.
A good caustic sealer remover is Klean-Strip Sealer stripper.
What type of sealer are you trying to remove?
Choosing the right chemical stripper for a concrete sealer removal project depends on several factors, with the most important being the type of sealer or coating to be removed.
Matching the strength of the stripper to the strength of the sealer is crucial for efficiency.
Thicker polyurethane and epoxy-based sealers require a more aggressive solvent-based stripper, while thinner acrylic-type sealers can be removed using a biochemical or caustic stripper.
For those who are unsure of the type of sealer used, basic guidelines include determining whether the concrete surface is inside or outside and the thickness of the sealer or coating.
Thinner sealers tend to be acrylics or enamels, while thicker sealers are usually high-performance epoxies or polyurethane-based systems.
To remove concrete sealer, it's important to first identify the type of sealer, or at least categorize it as acrylic or non-acrylic.
Next, consider the condition and thickness of the sealer. If the sealer is in good shape and adhering well to the concrete, an aggressive solvent-based stripper is necessary for removal.
However, for loose, flaking, white or failing sealer, a less-aggressive biochemical stripper may suffice.
When selecting a concrete stripper, it's essential to consider the location and environmental impact of the product on surrounding structures, plant life, and people.
Safety should always be a top priority. Solvent-based strippers generate flammable fumes and strong odors and should not be used indoors or in areas with sparks or open flames.
They can also be hazardous to people working or living nearby, and may contaminate water sources and kill plant life.
In contrast, eco-friendly biochemical strippers are an excellent alternative for these situations.
Although solvent-based strippers have been used successfully in public areas, proper safety measures, adequate ventilation, and site management are essential.
After using a chemical stripper to remove concrete sealer, the residue left behind must be removed.
On smooth concrete, a flat blade scraper is the best tool for the job, while textured or stamped surfaces require a stiff-bristle nonreactive scrub brush or broom.
After scraping or scrubbing, clean up the surface using soap and water, and consider using hot water and a high-pressure washer to remove any remaining residue.
Dispose of the waste in accordance with local and state environmental regulations.
All types of sealer removers and chemical strippers have instructions on how to use them printed on the container.
For the safest and in most cases the best results, follow the instructions carefully!
You don't want to harm yourself or your concrete by not following and doing what the maker of the product recommends.
Here are some tips to help you use chemical strippers safely and effectively:
By following these tips, you can safely and effectively use a chemical stripper to remove concrete sealer.
Remember to always wear protective clothing, follow the manufacturer's instructions, and dispose of the stripper properly.
Here are 10 frequently asked questions and answers about removing concrete sealers:
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