Frequently Asked Questions

How do I prepare the surface before applying a Mulco product?

Frequently Asked Questions

Q: How do I prepare the surface before applying a Mulco® product?

A: Preparing a surface for application of Mulco products depends on the condition of the surface. Follow these instructions for preparing a surface.

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New, Clean Surfaces

New, Clean Surfaces

If you are applying a Mulco sealant to a new, clean surface, you will have to do very little to prepare the surface.

Just wipe down the surface with a fresh, damp towel or sponge to remove dirt, dust and other particles.

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Previously Painted or Sealed Surfaces

Previously Painted or Sealed Surfaces

If you are applying a Mulco sealant to an area that has been previously painted or sealed, you will first have to clean and strip the surface.

Otherwise, the old caulk, dirt, paint and oil will prevent the sealant from adhering correctly.

Below we outline many methods for cleaning and stripping the surface.

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Cleaning the Surface

Before Removing Old Sealant

Cleaning the Surface

Cleaning should be done before removing old sealant, to avoid water infiltration in the gap. The majority of surfaces can simply be cleaned with trisodium phosphate (TSP), isopropyl alcohol or a bleach mixture. While chemical cleaning solvents are available to help clean surfaces, they can adversely affect the finish of the surface because they are so aggressive.

  • TSP Method: Follow the safety instructions and mix recommendations on the label. Spray the solution on the surface or juncture, and allow it to stand for a few minutes (without letting it dry). Rinse with clear water, and dry the surface with a clean towel.

  • Isopropyl Alcohol Method: Pour a small amount of isopropyl alcohol on a clean cotton ball or towel, depending on the size of the surface. Rub the alcohol into the stripped juncture. This will collect any residual debris and clean the area. You can also pour isopropyl alcohol into a clean spray bottle. Spray the alcohol onto the surface or juncture and then wipe it down with a fresh towel.

  • Bleach Method: Using bleach has the benefit of killing mold and mildew before you apply the new sealant. This is especially helpful in bathrooms. Mix a ratio of 1 part bleach with 3 parts warm water in a bucket. Use a sponge or clean towel to apply the bleach mixture to the area.

If you choose to use a chemical cleaning solvent, read and abide by all the safety guidelines recommended by the manufacturer.

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Stripping the Surface

Several Methods

Stripping the Surface

Stripping the surface means removing old layers of paint, varnish and sealant. There are several methods you can use to strip the surface:

  • using good, old-fashioned elbow grease

  • applying a chemical stripper/remover

  • using a heat gun

While nearly all sealants can be removed manually, some people find using the chemical or heat method easier when removing solvent- and chemical-based sealants.

Please note that silicone-based and urethane-based sealants can leave a residue that can only be removed with a specialized chemical stripper. If you use another method to remove a silicone-based or urethane-based sealant, you must replace it with the same type of sealant because the residue will prevent other types of sealants from adhering to the surface.

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Stripping the Surface

Manual Method

Stripping the Surface

The manual method is recommended when removing paint or sealant that has been previously applied to the surface. We recommend wearing medium-duty leather gloves to protect your hands during this process.

When removing old sealant:

  • Remove as much caulk as possible by manually scraping it out of the juncture.

  • Working slowly, slide a sharp utility knife or razor blade on either side of the existing seal.

  • A damp sponge will help loosen the old product.

  • Use a putty knife or razor blade-style scraper to scour the sealant out of the joint, pushing away from you. Be careful not to scratch the surrounding surface.

When removing old paint:

  • Depending on the surface, you can use a combination of a putty knife and wire brush to scrape off the paint.

  • Use a damp sponge or towel to wipe up loose paint flecks.

Once the majority of the paint or caulk is removed, you may use medium to fine-grade sandpaper or a non-metallic abrasive pad to remove the remainder of the old product.

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Stripping the Surface

Chemical Method

Stripping the Surface

Chemical strippers/removers are used to remove old coats of paint, stain, varnish and shellac from concrete, wood, metal, masonry and glass. Chemical strippers/removers are very caustic and require the use of safety goggles and a respirator.

If you choose to use a chemical stripper/remover, it is absolutely imperative that you read and abide by all the safety guidelines recommended by the manufacturer.

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Stripping the Surface

Heat Gun Method

Stripping the Surface

A heat gun is useful in removing multiple layers of paint or very hard sealants. The heat emitted from the gun softens the paint or sealant, causing it to bubble up so that you can easily remove it with a putty knife.

Because heat guns often reach temperatures hot enough to vapourize paint compounds, avoid using a heat gun on paints containing lead, cadmium or other volatile, toxic chemicals.

If you choose to use a heat gun, follow the manufacturer’s directions on proper usage.

After stripping the surface, spray your chosen household cleaner on the stripped surface or juncture, always following the manufacturer’s recommendations. Wipe the cleaner off the surface with a clean towel.

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