If you are applying a Mulco sealant to a new, clean surface, you will have to do very little to prepare the surface other than wiping it down with a fresh, damp towel or sponge to remove dirt, dust and other particles. 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.
1. Clean 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.
If you choose to use a chemical cleaning solvent, read and abide by all the safety guidlines recommended by the manufacturer.
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.
2. Strip 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 or 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- 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- 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.
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.
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.
Heat Gun Method
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.
If you choose to use a chemical cleaning solvent, read and abide by all the safety guidelines recommended by the manufacturer.
Household Cleaner Method: 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.
You can also pour the bleach mixture into a clean spray bottle. Spray it on the surface or juncture and then wipe it down with a fresh towel. If there is heavy mold or mildew in the area, spray the area and allow it to work for 5-10 minutes before wiping it off.
No matter which method you choose, ensure that the surface is completely dry before applying the new sealant. A dry surface will enable the sealant to adhere correctly.