[Expert advice] How to remove silicone sealant and its residue?

Sooner or later a silicone sealant joint in the bathroom or in the kitchen has to be repaired — because the joint has been damaged, for example, or because mold has started to grow in the old bead. But before new silicone sealant is applied, the joint has to be cleaned of the old sealant, of mold and of other contamination.

Why the old sealant has to be removed

Applying new sealant over old silicone makes no sense: the new sealant simply will not bond to the old one and the joint will not be tight. A joint with sealant residue left in it cannot be repaired, so the old sealant has to be removed completely.

How to remove silicone sealant properly

Cut the old sealant away

Cut away as much of the old sealant as possible with a sharp utility knife. Cured silicone is strong enough, and dissolving it is not easy. The thicker the layer, the longer and the harder it is to soften and remove it with chemistry alone.

Treat with sealant remover

Treat the remaining sealant residue with KUDO^® Multipurpose sealant remover KRS-920.

Shake the can well. Spray the product generously onto the surface from a distance of 20–30 cm. Let it work for 15–20 minutes.

Scrape off the residue

After 15-20 minutes the remover softens the sealant, so that it can be scraped off with a spatula and the surface wiped clean with a cloth.

Still some residue left?

If the joint has not been cleaned of the old sealant completely the first time, repeat the treatment.

Note that KUDO^® sealant remover can damage some types of plastic and some paint finishes. Before using the sealant remover on plastic or painted surfaces, test it on an inconspicuous area first.

What else can KUDO^® sealant remover be used for?

KUDO^® sealant remover can also be used to clean adhesive, grease, oil and some types of paint and varnish off a surface.

Silicone sealants from some manufacturers leave marks on the surface — oxidation on metal, oil stains in the porous materials around the joint. KUDO^® sealant remover unfortunately cannot get rid of those, so choose a suitable, good-quality sealant carefully in the first place.

Can sealant remover be used to clean mold off a surface?

KUDO^® sealant remover is not really meant for cleaning mold and mildew off surfaces. On silicone sealant it will remove the mold, but it will also soften the top layer of the silicone and can ruin the bead. Mold and mildew can be removed with any of the following:

• household cleaners containing chlorine bleach;
• dedicated antifungal products with a biocide;
• products based on strong acids, acetic or oxalic acid for example;
• hydrogen peroxide and potassium permanganate;
• baking soda;
• copper sulfate.

Once the joint has been cleaned of old sealant, mold and other contamination, let it dry and apply the new sealant to a dry, clean surface.