Adding lemon juice to vinegar improves its cleaning power.
OK, so Kristen says to add lemon juice to your vinegar to make a stronger cleaner. I just squeezed one lemon into a spray bottle and mixed in about a pint of vinegar. I reapplied this to the cushions and set them in the sun. While I can't say with certainty that it isn't due to a second application, they do seem to be improving even more. They are very nearly brand new looking now. The lemon juice improves the smell as well and since I understand leaving the vinegar on will prevent mildew from returning, the improved smell is big plus. Thanks Kristen!