NavList:

I have had very good luck with used old motor oil in my Davis plastic HA.  It's more than free. Your local gas station will gladly give you a small soda bottle full.  Used oil is a dark mix and does a fine job in eliminating reflected sun glare. Most of the time, I do not need a filter over the direct view.

Motor oil is far heavier than water and will not wripple with the wind. Your Davis cover glasses wont fog up either, something that happens with water if you are out shooting on a hot day.

You can eliminate clean up completely by lining the Davis tray with a small piece of Saran Wrap (thin plastic food wrap abailable at grocery stores) before you pour in the oil. Then shoot away. When you are done taking sights, pour the oil back into the soda bottle for your next shooting session. Discard the plastic liner.  No oil ever touches you or your Davis AH.

It works like a champ.