My faux wood blinds have yellowed over the past few years, any suggestions on how to get them white again? No amount of dusting or cleaning with soapy water have returned my blinds back to their original appearance. I believe the yellowing may have been related to natural gas, as I have the same blinds in my garage and they have not yellowed. Help, I don’t want to buy new blinds to only have the same thing happen again. Thanks!