A Better Focus Co.
Questions and answers
Can the cooking system be utilized on a cold or windy day?

Yes.  The sun's radiant energy being focused is unaffected by air temperature or
wind.   On cold days, you will notice that the reflective film will appear to be loose
over the frame.  The dish has been designed with a thermal tensioning system,
however.   Facing the dish into the sun for a few minutes before pulling a vacuum
inside will stretch the film tight.  The dish has been successfully tested to
20 degrees F.
Although wind does not affect the radiant energy being delivered to the cooking
surface, it can remove heat from the food being cooked.  Cooking pan and inverted
oven accessories both utilize an optional thin, clear, film cover that can be placed
over the food  to retain heat, while permitting the radiant energy to pass through.  
Make sure that all cooking stands are well supported in windy conditions.   

Will the dish work on a cloudy or hazy day?
Performance is degraded by clouds or haze.  Even a bit of haze significantly reduces
the solar radiation available.  Best performance is on dry, clear days.  See  test data
in specifications.

Do you offer kits for people to build their own solar cooking systems?
Many customers build their own cooking accessories (pans, ovens, mounts, etc.),
but most have been disappointed with the results of homemade dishes.  We have
designed manufacturing fixtures to ensure that the frame is perfectly round, and the
film is stretched uniformly over the frame.  Hand stretching the film will result in a
concentrated spot that is too large, or of an odd shape that is hard to place on a
cooking surface.   Finally,  the large dish circumference (app. 12' circumference for a
4' diameter dish) is difficult to seal, and one ends up spending much time pumping to
keep a good vacuum inside the dish, and less time enjoying the cooking.  Our dishes
will hold vacuum for several hours, or longer.

Any suggestions on how to store such a large dish?
The dish cannot be left outside.  Ultraviolet light will degrade the reflective material in
just a few months.  (the 8' diameter power dish is constructed of materials suitable for
ourtdoor use).
Many people hang the dishes on a wall. Some will attach a poster to the back of the
dish, or decorate the back.

Can the reflective film be cleaned?
Yes, but it's best to keep the film clean.  Always keep the reflective film covered when
not in use.   This keeps dust off of the film, protects the film from punctures during
handling, and finally, prevents fires from unattended dishes.   Light dust can be
blown off with compressed air.   A pressure washer is the preferred method of
cleaning.  Contact washing with a cloth can scratch the membrane material, and is
not recommended. Use distilled water to minimize spotting from dissolved minerals in
the water. Excess water can be blown off with an air hose.

What if the reflective film gets punctured?
Small punctures can be simply taped over with scotch tape so that the dish can still
be evacuated into a concave shape.  Large punctures that cannot be taped will
require recovering.