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The installation of a bathtub must be carried out in the rules of the art to avoid that with the time of disorders appear. Cracks and loose joints must be repaired as soon as possible...

laying a bathtub seal

If the bath is not equipped with a protective screen, the water trickles around every time and inevitably slides along the deck. Over time, cracks eventually appear, especially if the seal is not perfect. This is the case in this bathroom.

The dressing of the bathtub was made with simple plaster tiles not waterproof, unsuitable for wet rooms. On the other hand, the seal did not fit perfectly round the edge of the bath. Filled with plaster, this joint was very sensitive to runoff. A crack was formed along the deck, the connection between the tiles and the wall (also note that the building worked to the point of causing other cracks in the room...).


Before any treatment, the crack must be widened and dusted to promote the grip of the filler (type "Chrono" Toupret). This is mixed up in a small trough, mixing the powder in the water until a creamy paste is obtained (5 vol of powder for 2 vol of water). The coating is then applied in the crack with a spatula, if necessary in several passes. Indeed, the coatings are deep in drying, especially if they are thick. If only one layer is sufficient, it must be immediately smoothed. For large or progressive cracks, the application of a fiberglass calico strip, embedded in the fresh plaster, is recommended.
Finally, it is necessary to wait for the complete drying, ie several days, before making the connections of paint.

Make a new seal

To change a joint and promote adhesion of new sealant, the substrate must be clean and dry. The old seal is deleted, here using a specific product (see box above).
Degreasing with a sponge and soapy water is then recommended.
For the seal is impeccable, just use two bands of masking tape, posed paralèllement.
The space between the two strips is used to delimit the width of the new joint.
Be sure to remove the strips quickly: the sealant hardens in less than 15 minutes and may be torn off when the tape is removed.
Note that silicone sealants can not be painted, unlike acrylic mastics or polyurethanes.

Open and clean the crack

opening the big crack with a scraper

To dig a crack along ceramic tiles, the use of a chisel is effective. But you must act with caution so as not to damage the tiles.

Open the large crack with flat chisel and chisel or with a triangular scraper with a strong blade. Dust thoroughly with a brush and vacuum.

Inject mastic

injection of putty into the crack

Before filling the plaster, inject acrylic sealant at the bottom of the groove using an extruder gun. The crack is thus stabilized.

Stuff with plaster

stuffing filling stuffing

Stuff with filling compound, pressing firmly on the blade of the spatula.
Here, the use of a strip of calico to drown in the plaster "would ride" the tiles.

Apply smoothing plaster

surface sanding

After drying, apply a coat of smoothing compound.
Allow to dry and sand the surface with a fine abrasive (80 grit, then 150 grit) and a sanding wedge.

Cut out the gradient seal

remove the silicone seal with the cutter

To eliminate old silicone seals, some products are effective such as "Seal Remover" (Rubson). This is in the form of a gel and requires one to two hours of waiting before being removed with a spatula (or cutter) with the remains of the sealant.

Slice the degraded silicone seal all along its length with a cutter. This cut is rarely enough: some parts of joint often resist...

Eliminate the old seal

remove the used bathtub seal

To completely eliminate the old seal, apply a product to soften it.
After one hour, scrape with a cutter or spatula, rinse with water and allow to dry.

Delimit the edges

edges delimited by the adhesive tapes

To obtain a straight seal, mark its edges (approximately 4 mm wide) with two parallel strips of masking tape glued to the bath rim and the wall.

Apply the new seal

application of the new bathtub seal

Cut the nozzle of the cartridge bevel, to the diameter of the joint.
Apply a continuous bead and smooth with your finger dipped in soapy water.
Remove the adhesive.


Video Instruction: How to repair a cracked bathtub the right way