I use straight bleach and rinse with water, but of course this is done with the pop top off upside down on saw horses during the process of replacing the canvass.  I have at times cleaned the ceiling in situ with pure bleach and it does work out well but you will need some serious airing our afterwards.  As far as damaging the ceiling, pure bleach will not damage the fluid on the ceiling.  It may spot the canvass if it gets on it or any other materials nearby.

> On Apr 16, 2016, at 9:00 PM, Automatic digest processor <LISTSERV@GERRY.VANAGON.COM> wrote:
> 
> I have some moderate mildew spots on the pop=top ceiling, and would like to know what the ratio of water to bleach is, in a one gallon container?
> It'ss been a while since I cleaned it, and I think the last time I made the solution with too much bleach.

      Please note that I will be away from my business travelling from November 16 until April 30, 2016.  Parts orders will be processed although not as quickly as usual.  I will always be available for contact by E-mail.  If you phone your call will be addressed by Steven and he will either call you back or advise you to contact me directly by E-mail.  

Cheers, 
   
Frank Condelli
Almonte, Ontario, Canada
'87 VW Westy, '00 Kawasaki 250 Sherpa, "98 Ducati 750 Monster & Lionel Trains (Collection for sale <http://frankcondelli.com/trainsal.htm>)
Frank Condelli & Associates <http://www.frankcondelli.com/> - Vanagon/Vanagon Westfalia Service in the Ottawa Valley
BusFusion <http://www.busfusion.com/> a VW Camper camping event, Almonte, ON, June 02 ~ 05, 2016