A home’s ventilation, heating and cooling system, humidity and air quality all become factors in how—and how often—venetian blinds need to be thoroughly washed. Frequent buildup of condensation on the blinds, which happens as warm, moist inside air comes in contact with a cool windowpane, causes blinds to become dirty at an accelerted rate. Well-insulated, double-paned, and storm windows keep window glass warmer, reducing this effect.

To thoroughly wash venetian blinds in the bathtub:

1. Remove the blind from the wall. To do this, use the rotating bar to tilt the blind’s slats to a horizontal, level position. Then pull the cord so the blinds go into the full “open window” position, where they stack together tightly at the top.

2. If necessary, stand on a stepladder or footstool and bend open the brackets holding the blind to the wall and then tilt the mechanism out and remove the blind.

3. Lay an old blanket or a few towels along the floor of the bathtub (or any large basin) to act as a pad to prevent damage to the blinds. Fill the tub with warm water to about 5 inches deep.

4. Carefully place one of the blinds into the water, laying it on the submerged fabric. Protect your hands from being cut on any sharp edges by wearing heavy cotton gloves.

5. Add liquid dishwashing or laundry detergent to the water. Mix it in well, but try not to make too many suds.

6. Using a cotton cloth or soft sponge, rub soapy water along the surface of each slat, front and back. (You may need to pull the cord to allow the blinds to open just a bit.) Clean the tapes on the edge of the blinds as well.

7. Drain the water and stand the blind on its side in the bathtub. Pour clean water over the blind to rinse away any leftover soap. You can use a bucket or turn on the showerhead.

8. Lean the clean blind standing on end against the wall. Allow 30 minutes or so for it to drain.

To dry the clean blind:

1. Replace the blind into its window brackets.

2. Release the control cords so the blind can extend its full length to the bottom of the window.

3. Tilt the slats if necessary. Use a clean, dry cloth to carefully dry each of the slats, top and bottom. You may need to rotate the slats all the way around to get to the bottom side.

4. Leave the blinds in their extended position, with flaps open (all at horizontal level) to fully dry.