Things You'll Need
Caulk remover or razor blade
Low-tack masking tape
100-percent silicone caulk
Caulking the seams of an acrylic bathtub and wall surround creates a barrier that keeps water from leaking behind the tub and the wall surround. Leaking water causes mold, mildew and structural rot making the bathroom unhealthy and unsafe. Cleaning and preparing an acrylic bathtub and surround surface properly is necessary to get the caulking material to adhere tightly. Using the correct type of caulking material is key to successfully caulking the acrylic tub and surround.
Remove the old caulk from the gap between the bathtub and surround with caulk remover, or scrape it carefully off the surface with a razor blade. If you use a caulk remover, apply the remover to the caulk and let the remover sit on the caulk until the caulk is soft and pliable. Scrape the old caulk away with a plastic scraper.
Spray a clean rag with an all-purpose cleaner, and wipe the bathtub and wall surround with it.
Wet the corner of a rag with isopropyl alcohol, and use it to wipe the area where the caulk will lay. Isopropyl alcohol removes oils and prepares the acrylic surface to accept caulk.
Position low-tack masking tape on the edge of the tub 1/4 to 1/2 inch away from the gap. Also place low-tack masking tape on the edge of the surround 1/4 to 1/2 inch away from the gap.
Fill the bathtub with water. Filling the tub with water adds extra weight to the tub and pulls the gap apart. If you do not fill the tub with water before applying the caulk, the first time you fill the tub with water, the caulk will separate from the surround.
Insert a tube of 100-percent silicone caulk into a caulking gun. Position the tip of the tube at the edge of the tub. Squeeze the caulking gun's trigger while pulling the caulking gun along the gap. Squeeze a continuous line of caulk.
Dip a plastic spoon in water. Place the back of the spoon on the caulk line and drag it along the caulk while pressing the caulk down.
Remove the low-tack masking tape immediately. Let the bathtub remain filled with water for 10 to 15 minutes before draining the tub.
Consider wearing a pair of shorts or a bathing suit and stepping into the water-filled tub to caulk the gap. Caulking from inside adds more weight to the tub and saves your back from the strain of stretching over the tub.
Do not wait more than three to four minutes before smoothing the caulk, because most silicone caulks set up within five to 10 minutes.