I agree-bathtub soaking is the best way to clean dirty plastic mini-blinds. Glad you can recommend OxyClean.

OxyClean is amazing! My son came home from school and his tennis shoes were horrible. He was embarrassed to wear them anywhere because they smelled so bad. I thought I'd try to wash them before I ran out for new ones. They soaked in the sink for a couple of hours in OxyClean and then I tossed them in the washer and voila! good as new! It's also great for soaking sports uniforms that have spent way too much time in a locker!

That black stuff on your blinds (and curtains and walls) is carbon and is caused by either burning candles, smoking cigs/cigars, fireplace or furnace that doesn't vent correctly.

Smoking candles cause so much damage that people need to know to use them only sparsely.

Well no one smokes here and I don't burn candles because of my Dad's asthma so it must be the oil furnace. It is vented to a chimney and we had the furnace and the chimney cleaned so I wonder why it is still black residue there. My sister said laser printers sometimes give off stuff too but I have an ink jet not a laser.

My recommendation for cleaning metal/plastic blinds is degreaser, a garden hose, a warm, breezy day. Mix up the degreaser in a one of those pump-up type sprayers and spray down the blinds. Hose down to rinse any dirt away. Allow nature to dry.

Mike..I would have cleaned them outside too except it is 20 degrees here now and the hose is put away until Spring! What is the degreaser you use?
Joann