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This booklet was prepared by a team of VITA Volunteers


Edmund Hazzard, St. Louis, Missouri
Dr. Robert G. Luce, Schenectady, N.Y.
Jon E. McNeal, Rexford, N.Y.

Art work:
Ed Gutowski, Schenectady, N.Y.
Jim Curtis, Schenectady, N.Y.

ISBN: 0-86619-017-1



construction manual

Prepared By:

1600 Wilson Boulevard, Suite 500
Arlington, Virgnia 22209 USA
Tel: 703/276-1800 * Fax: 703/243-1865
Internet: pr-info@vita.org


The VITA Solar Cooker was especially designed to be sturdy, relatively
easy to make, easy to repair, and low in cost. It uses the principle
of the Fresnel reflector which concentrates light and heat by using
several simple reflecting surfaces. Most other cookers use a doubly-curved
reflecting surface. The VITA Fresnel design has a number of

-It gives a broad uniform focal region the size of the cooking
pot rather than a sharp, intense spot of heat, making it
safer and more efficient;

-Rings can be added or removed to increase or decrease the
cooker's power output;

-The solar cooker described in this manual is designed to
give enough heat for the cooking needs of a medium-sized
family (3-5 children),

-to use cheap readily available materials. In the United
States the materials used are mainly Masonite sheet,
aluminized Mylar, wood, and iron strip. In both the United
States and Morocco, the cost of materials is about three
dollars ($3.00). In developing countries the Mylar will have
to be imported but it is lightweight and inexpensive,

-to be as simple as possible.

The VITA Solar Cooker requires more labor than, for example, forming
a paraboloidal reflector by spinning an aluminum sheet; the labor requirement
may make it uneconomical for developed countries, but this cooker was
designed specifically for developing ones.

Before one decides to begin manufacturing this solar cooker, there
are some serious drawbacks that should be considered carefully. It is
generally agreed that an average of 2,000 or less hours of sunlight per
year is too little for the cooker to be practical. It should also be
pointed out that the cooker will be more effective in dry climates and
high altitudes.

The cooker is not effective early in the morning or late in the
afternoon; therefore it could not be used by people who ordinarily eat
their large meal in the evening. Also the women must accept doing their
cooking outside in the open.

Though the cooker is not difficult to use once one is accustomed to
it, it does require some instruction. Experience in Morocco indicates
that learning to use it is about like learning to knit; therefore one
can probably not expect a "natural" market to exist; one must be prepared
to follow up manufacturing with personal introduction.

Although the cooker construction is not difficult, spreading the
Mylar on the glued Masonite is tricky and requires some practice. One
will probably ruin the first few cookers in the process of learning.
Therefore it is probably impractical to plan on making fewer than a
dozen or so cookers as a start.

Lastly, and perhaps most importantly, one wants to be sure that
other cooking procedures are comparatively quite expensive. Exactly
how much time or money does the average family spend on obtaining fuel
and hence how long would it take to recover the initial investment by
savings on fuel costs? This is probably an important consideration in
a subsistence agricultural economy where there is not much cash available.
Also, of course, the cooker can never be used all the time so it can
never substitute completely for convential cooking methods.


This section lists all the tools and materials needed to build the
VITA Solar Cooker. The best choice of materials may vary from
place to place. Other kinds of wood or composition board may be
cheaper than the materials indicated here in some countries. Any
sheet material such as plywood or certain sheet metals, can substitute
for the Masonite.

A. Reflecting Surface


Fine sandpaper
Paint brush
Safety razor blade or sharp knife
Clean, dry, lint-free cloth
Two (2) spoons
Rubber blade window washer (squeegee) or a smooth
stiff rubber windshield wiper
Rubber roller (double print photograph roller)
Four (4) boards 5 =. x 5 cm. x 135 cm.
Hammer and coping saw (bandsaw if available)
Ruler and pencil


About 120 cm. x 120 cm. Masonite (0.3 cm. to 0.6 cm. thick)
as free as possible of pits and structure defects,
80% - 95% ethyl alcohol approximately 50 cc/cooker
Epoxy cement (resin, hardener, and solvent 80% - 95%
alcohol) approximately 75 cc. of mixed cement
Clean dry cup
Clean smooth stick (size of pencil)
A roll of aluminized Mylar (.0005" thickness) 160 cm. wide
Polyurethane paint or if not available use good oil paint

B. Frame


Paint brush
Ruler and pencil
Hammer, hand saw
Screw driver
Drill capable of drilling metal (6 mm. diameter)


15 cm. strip of 18 mm. x 3 mm. hot rolled iron
Two (2) 2 cm. x 120 cm. boards (oak for strength but pine
or other woods are sufficient)
Two dozen aluminum nails (or screws) about 5 cm. long
(or other non-rusting material)
10 cm. x 6 mm. bolt with fitting wing nut

C. Utensil Holder


Ruler and pencil
Drill capable of drilling metal (6 mm. diameter)
Cold chisel or metal cutting hand saw


40 cm. strip of 18 mm. x 3 mm hot rolled iron
50 cm. strip of 18 mm. x 3 mm. hot rolled iron
Wood stock 25 mm. x 25 mm. x 80 cm. preferably a hard wood
Two (2) 25 mm. x 6 mm. steel bolts and fitting wing nuts
One (1) 11 cm. x 6 mm. steel bolt with fitting wing nuts
One (1) 3 cm. x 6 mm. steel bolt with fitting nut


Note: Be sure you feel you can complete all the steps before
starting construction.

Construction can be divided into nine parts:

1. Applying a sealing finish to the Masonite
2. Making the surface smooth and dust free
3. Applying thin uniform coat of adhesive
4. Applying the aluminized "Mylar"
5. Cutting out the rings
6. Preparing the legs
7. Bending the rings into shape and mounting them on the legs
8. Providing a cooking vessel support
9. Providing an adjustable brace

1. Applying a sealing finish to the Masonite (to keep the Masonite
from absorbing glue and moisture).

A. If the 120 cm. x 120 cm. Masonite is rough to the touch,
sand it smooth with medium sandpaper. If it 1s already
smooth, this step can be omitted.

B. Brush polyurethane paint smoothly on both sides of the
Masonite, covering all areas. If polyurethane paint is
not available, a coat of epoxy cement may be used in
the front side (the side to be used as the reflector),
and varnish or lacquer may be used on the back. Do not
use varnish or lacquer on the front.

C. Let the paint dry on a dust-free area.

D. Clean the brush with oil base paint thinner (or
alcohol for varnish, or water for epoxy).

2. Making the front surface smooth and dust free.

A. Choose the smoother side of the Masonite as the front
(or the side with epoxy already on it.)

B. Using a safety razor blade, remove major imperfections,
such as drip marks, from this front side.

C. Rub the surface smooth with steel wool or fine sandpaper,
until it feels very smooth to the touch. If it does not,
apply another coat of sealer to the smooth side, let it
dry and sand it again.

D. From scrap wood cut out four (4) wedges 10 cm. long and
5 cm. high as shown in Fig. 2. These will be used in part 4.

scc2x7.gif (486x486)

E. Nail four (4) pieces of scrap wood into a 150 cm. square
frame as shown in Fig. 1. This will be used in step 4.

scc1x5.gif (486x486)

3. Applying a thin uniform coat of adhesive. See Fig. 2.

Note: Before you prepare the epoxy, complete steps 4A and
4B so that the Mylar will be ready to be glued.

A. Some important notes to remember about epoxy-resin

The cement hardens in about 20 minutes on the
tools and in a bit longer time when spread
on the Masonite.
Once hardened, it will not dissolve again even
in its own solvent.
Before hardening it may be dissolved in water,
but once water is added it will never harden.
Wash all tools and containers which touch the
cement with water before it hardens if you
want to use them again.
Do not let water come into contact with the cement
being used for the actual cementing.
Do not mix hardener and resin except when actually
preparing to use it.
Do not put a spoon covered with hardener into the
resin can.
Do not put a spoon covered with resin into the

B. Mix equal portions of hardener, resin and 80% - 95%
alcohol in a clean dry cup with a clean smooth stick.
Two tablespoons or six teaspoons of each should be

C. Dust the Masonite surface with a clean, dry, lint-free
cloth immediately before applying the prepared cement.
Place the Masonite on a table or a similar large flat
surface, preferably above the ground, to lessen the
amount of dust that will settle on the surface while
you are working.

D. Pour the prepared cement on the center of the Masonite
and spread it evenly over all the surface in a very thin
coat with a stiff squeegee or rubber blade. Use long,
smooth strokes to prevent ridges and press down quite
hard. (See Fig. 2.)

E. Roll the cemented surface with a double-print roller until
the surface appears shiny and uniform from a glancing
angle. Work out ridges and regions of varying thickness
by going back and forth in various directions. Again,
press down quite hard.

F. Clean all the equipment within a half-hour. (You can
finish the next step first if you have time.) Don't
let any water get on the cemented surface of the Masonite
and keep the surface away from dust. The cemented surface
will stay workable for at least a half-hour.

4. Applying the aluminized Mylar.

A. Decide which side of the Mylar is aluminized. It is
the underside of the roll (if the Mylar comes in a
roll) or the shinier side or the side from which the
aluminum can be rubbed off with your fingernail and
you can see the scratches you have made, through the
Mylar. The last test is absolutely certain.

B. Using a safety razor blade, cut a 160 cm. x 160 cm.
square section from the Mylar roll.

C. Nail the Mylar to the top of the 135 cm. x 135 cm. square
frame (from step 2E) with the alumunized side down. Use
small nails or carpet tacks or thumb tacks or staples
every foot or so, or nail down four (4) wood strips
along the frame. Stretch the Mylar tightly enough so
that it hangs down a few centimeters in the center. The
Mylar is very strong but it tears very easily so be careful
when you nail it down.

See Fig. 1 for the above two steps. If you have a
Mylar roll, the easiest way to fasten the Mylar is to
drape it vertically down in front of the frame.

D. Place the frame over the glued surface of the Masonite
on the four (4) wedges with the aluminized side down.
Pull the wedges out until the center of the Mylar hangs
a few cm. above the center of the glue-covered Masonite.
(See Fig. 3)

scc3x8.gif (486x486)

E. Apply the Mylar to the Masonite with a stiff dry squeegee,
working from the center outward (see Fig. 3A), using

scc3ax9.gif (486x486)

short, firm strokes. Try to keep the Mylar quite taut
between the glued area and the frame so that the Mylar
does not touch the Masonite until the squeegee strokes
pull it down. If the Mylar rips from the frame and falls
on the Masonite, it will form many ridges and bubbles.
In any case, ridges and bubbles are sure to form and the
Mylar must be lifted and reapplied in the wrinkled regions.

Try the following procedure: spread the Mylar, starting
from the center as far toward the edges as possible, using
the tension suppled by the frame. Gradually lower the
edges, let the force of the strokes rip the Mylar from
the frame. If serious ridges or bubbles appear far from
the edge, free the Mylar from that region either by
lifting the frame or by ripping the Mylar from part of
the frame and pulling it upward and outward by hand. Don't
worry about the four corners as they will be sawed off

Remember that applying the Mylar is the most difficult
part of building the solar cooker; it takes some practice
and patience and you are fortunate if the first few
efforts are successful.

F. Trim the overhanging edges of the Mylar with a razor blade.

G. With a needle or the razor blade, puncture all the air
bubbles and press them down; small air bubbles fixed in
this way are hardly noticeable afterward.

H. Clean the surface of any traces of glue with a damp cloth.

I. Allow one day for the glue to dry.

5. Cutting out the rings. (see Fig. 4)

scc4x10.gif (486x486)

A. Locate the geometric center of the Masonite by marking
where the two diagonals meet. Be careful not to tear
the Mylar.

B. Cut out the rings with a coping saw or a jigsaw if one
is available, using the holes in the supplied template
as radii. It may be convenient to nail down the center
and rotate the whole sheet, keeping the saw stationary.
This may save the trouble of drawing out the rings.

C. From the inner ring cut out a section with a width at
the outer edge of .5 cm.

D. From the next most inner ring cut out a section with
a width at the outer edge of 2.8 cm.

6. Preparing the legs.

A. Cut Out the two legs, using the template enclosed. (You
may wish to copy the template onto sheet metal.) Use
2 cm. x 12 cm. x 150 cm. pieces of wood. At the center
notch one leg from above and one from below as shown on
the template, so that their edges are flush.
B. Fit the two pieces together at the 2 cm. center slots.
Cut a wooden tie bar about 40 cm. long (with 45[degrees] ends if
you would like) and nail or screw it to the backs of legs
so that the legs form an angle of exactly 90[degrees]. (See Fig. 5)

scc5x11.gif (486x486)

7. Bending the rings into place and mounting them onto the
legs. (See Fig. 6)

scc6x12.gif (486x486)

A. Place the inner ring (#1) on the frame and squeeze it
closed at one of the cross pieces, nailing both ends to the
same leg. Nail down the ring at the other places where it
crosses the frame as well, using 5 cm. aluminum nails (or

B. Do the same thing with ring #2; the ring should fit
easily into the slots in the legs.

C. Saw through ring #3 if you haven't already. Work it
into the slots on the frame and ovelap it somewhere
between two crosspieces. It should overlap 8.8 cm. on the
outer edge and 6 cm. on the inner edge. Clamp it into place.

D. Do the same with the outer ring (#4). It should overlap
19.8 cm. on the outer edge and 14.5 cm. on the inner edge.

E. Place a light source about five meters from the cooker
and point the cooker at this source. Looking at the
cooker from about a meter directly in front, adjust
rings #3 and #4 until the reflection is even all the
way around all four rings. If the rings and legs have
been properly cut, very little adjustment would be

F. When you are satisfied, there are two ways to fasten
the outer two rings in place:

1. Close the rings by bolting or riveting
them through the Masonite where they
overlap, at two or three locations not
lying on the same radius. Then nail
them to the frame; or:

2. Cut a wider slat in one of the crosspieces
and overlap the rings on top of this
crosspiece. Nail through the two layers
of Masonite. This latter method is less
durable and produces a less satisfactory
shape of the outer rings.

G. Clean the rings with a damp cloth and paint or tape
the expanded edges of the rings to prevent weathering
underneath the Mylar.

8. Providing a cooking vessel support.

Any support will do as long as the pot is placed so that the
pot rests in the bright focal region about one meter from the
cooker. A separate tripod is one possibility. Another
design is as follows:

A. Drill a 6 mm. hole about 2 cm. from one end of a 50 cm.
x 18 mm. x 3 mm. strip of hot-rolled iron. Using a cold
chisel, make radial indentations around the hole on one

B. Bend the strip into a circle of the desired dimeter
(the right size to hold a cooking vessel), with the
chisel marks on the outside of the ring formed. A
round wooden form will help.

C. Drill a 6 mm. hole in the other end of the strip at the
place where they overlap to form the closed ring. Drill
another hole directly opposite this one.

D. Drill a 6 mm. hole 1 cm. from each end of a 40 cm. x 18 mm.
x 3 mm. strip of hot-rolled iron. Score around earch hole
with the chisel. Place this strip in a vise so that the
middle 10 cm. are securely held. Grip the strip about
4 cm. from the vise with a wrench with adjustable jaws;
give a quarter turn so that the end is horizontal. Repeat
this with the other end. (Fig. 7)

scc7x14.gif (486x486)

E. Bend the horizcntal ends to form a "U" with the chisel
marks on the inside and the ends about as far apart as
the width of the ring formed in step B. (Change the
dimensions in step D if necessary.) Drill a 6 mm. hole
in the center of the bottom part of the "U".

F. Cut a 2. 5 cm.-deep slot diagonally into one end of the
support rod (25 mm. x 25 mm. x 80 cm.), a little narrower
than 3 mm. Flatten the edges of the rod and drill a
6 mm. hole across the slot. (Fig. 8)

scc8x15.gif (486x486)

G. Secure the metal "U" in the slot with a 3 cm. x 6 mm. stove
bolt. Mount the metal ring between the ends of the "U" with
two 25 mm. x 6 mm. stove bolts and fitting wing nuts, with
lock washers between the ring and the "U" if you wish.

H. Cut a short triangular wooden block to fit snugly into
position at the vertex of the two legs. Nail it in place.

I. Take the cooker outdoors. Rest the support rod in place
in the vertex of the two legs, place a pot in the metal
ring and aim the cooker at the sun. Change the distance
which the support rod projects until the brightest part of
the focal spot is on the bottom of the pot. Mark the position
of the support rod.

J. Chisel off the upper edge of the support rod at its lower
end and drill a hole down through it, the vertex of the
legs, and the triangular wooden block. Bolt the rod in
place with an 11 cm. stove bolt with fitting wing nut.
(Fig. 9)

scc9x16.gif (486x486)

9. Providing an adjustable brace.

Brace the cooker in a position facing directly into the sun
so that the bright focal spot is on the bottom of the cooking
vessel. It must be adjusted about every twenty minutes as
the sun moves. The angle adjustment can be done with notched
pieces of wood propped against the tie bar. A better system,
however, is the leg assembly shown in Fig. 9. This will be
more secure. It requires s strip of iron, two 4 cm. bolts,
a longer bolt, and two pieces of wood, one about twice as long
as the other. Their exact length will depend on your latitude
and the time of day the cooker is commonly used.

Anchor the legs firmly to keep the cooker from being blown
over by the wind.

Aluminized Mylar and epoxy may have to be imported.
Addreses where they can be obtained in the United States

.0005-inch chrome metalized Mylar, 160 cm. wide, $1.00
U. S. per yard:

Coating Products, Inc.
101 West Forest Avenue
Englewood, New Jersey 07631

Epoxy: Astro Special 1100, 8 pounds per gallon
at $1.30 U.S. per pound.

Hardener: Astro Special 2950, 8 pounds per gallon
at $1.65 U.S. per pound.

Astro Chemical Company, Inc.
1205 Godfrey Lane
Schenectady, New York 12309

Figure 10. Using the Cooker

scc10x18.gif (486x486)

1. Install the support rod in place in the vertex of the two legs.
Aim the cooker at the sun.

2. Adjust the support rod so that the brightest part of the focal
spot hits the bottom of a pot placed in the support. Drill a
hole through the support rod, the vertex of the legs and the
triangular wooden block. Bolt the rod in place.

3. Brace the cooker so that it faces directly into the sun, with
the bright focal spot on the bottom of the cooking vessel. The
shadow of the cooking vessel will be in the center of the cooker.
If the shadow is outside the center, the cooker is not facing
direatly into the sun.

4. Adjust the cooker every 30 minutes as the sun moves.


This template is to be used to make a 152-cm
(5-toof) template for the legs of the VITA
Solar Cooker. See Paragraph 6A and Fig. 5,

scc5x11.gif (486x486)

page 11. The complete template is AB (88.5cm)
plus BC (63.5cm). To make the template,
cut out the four pieces shown and

sccdr190.gif (600x600)

string or a straightedge
to be sure ACB is a
straight line.


Although we are sending you the VITA Solar Cooker Manuals, we feel
it is important to point out some limitations in its use. These are
partially covered on pages 1 and 2 of the manual and are repeated here
for emphasis.

The VITA Solar Cooker is not useful for day by day cooking in most
circumstances. To be useful requires understanding of the following

1. The cooker is probably not practical where the
average of the hours of sunlight is under
2000 hours per year.

2. The cooker is not useful for cooking meals in
early morning or late afternoon.

3. The cooker must be frequently shifted in position
during use (once every 10 minutes or so) to take
advantage of the sun's position.

4. Making a good contact between the Mylar film and
its backing is tricky and requires practice. One
will probably ruin a few cookers in the process
of learning how to make this seal. For this
reason it is important to order enough materials
for a few cookers in hopes of getting one good
one. After this techniques mastered, there is
little material spoilage.

5. It requires the development of some technique
to cook with the cooker. This process can be
developed by a trial and error procedure. So
experienced people have compared this learning
process to be about as difficult as learning how
to knit.

6. In many areas of the world the cooker cannot
compete economically with existing methods of
cooking. For example, one should calculate how
long it would take to recover the initial investment
in the cooker from the savings on fuel that
come about because of its use.

7. To properly introduce the cooker to a local
populace requires careful thought and painstaking
effort. Those experienced in the process of
introduction should be consulted to see how it
can best be put to use in the given culture.
Aside from local taboos (religious, social
traditional, etc.) there will be the very formidable
barrier of resistance to change. People will be quick
to point out the difference in taste (whether there is
one or not) the longer or shorter cooking times, the
space required to store the heater, the need for being
outside while cooking, etc.

Nevertheless, the cooker does represent a method of putting the
free-for-the-asking energy of the sun to work, and if this can be
accomplished economically in your community, it will bring the further
advantages of a more smoke-free atmosphere, less real danger of open
flame, and an opportunity to prove to the local people that a new
method can sometimes prove to be an advantage over old procedures,
thereby reducing that major obstacle to progress, "resistance to

If you decide to go ahead with the construction and introduction
of the cooker with full knowledge of its problems and limitations, and
you think through a plan of introduction, you could well make a real
contribution to the people of your community. Do not, however, expect
to quickly build a cooker properly the first time and be adequately
cooking with it on your first try. Good luck in your efforts.


VITA has been able to locate a substitute for one of the less easily
obtainable materials (aluminized Mylar film) called for in the solar cooker
manual. That substitute is aluminum foil. The problem of using aluminum
foil, however, is that conventional attempts to fasten the foil yield discouraging
results (the foil wrinkles easily) and commonly available cements
and/or glues will not hold the foil to the cooker surface adequately. The
following procedure, then, will help you over the difficulties of applying
aluminum foil successfully:

1. Remove the foil from the roll with a minimum of wrinkling;

2. Apply the cement in the same manner mentioned in the manual.(*)
However, apply the cement to not more than one foot of the
cooker surface at any one time;

3. Gently lay on appropriate length of foil down on the cemented
surface while anchoring one end of the foil with one hand to
prevent it from slipping;

4. Smooth the foil with your right hand, keeping that hand wet
by dunking it in water (if your right hand becomes dry while
rubbing the foil, it will tend to bounce along the foil,
causing ridges);

5. The foil is then rolled with a roller. Do not press hard on
the roller;

6. Repeat the above process on successive sections of the cooker
surface until the cooker is covered. If too many wrinkles appear
on the foil, remove that section and try again.

(*) One substitute for the epoxy cement shown in the manual is "waterglass"
(sodium or potassium silicate). A fairly strong solution of
water-glass when applied as a substitute to the epoxy cement will
harden within 20 minutes when placed in direct sunlight. Note that
"water-glass" will dry most rapidly in dry climates, so where
extended drying periods are needed, do the gluing in a cool damp room.
The water in this mixture will tend to soak through the masonite; therefore
it is suggested that you place the masonite disk on a flat surface
to prevent warping. And if the glue is too thin, it can be
made more pasty by mixing in a smooth filler powder such as red lead
or kaolin, without affecting its hardness or stregth.

Material submitted by:

Mr. Terance Maaske
Scottsdale, Arizona

IF YOU NEED MORE manual or on other technical matters, VITA (Volunteers in
Technical Assistance, Inc.) can send it to you. If you
have specific questions, VITA can put you in contact with
an expert who can answer them.

VITA is an international association of scientists,
engineers, technicians, businessmen, educators and others
who volunteer their spare time to consult on questions
from persons in developing areas.

Simply send your request to:

Volunteers In Technical Assistance
1600 Wilson Boulevard. Suite 500
Post Office Box 12438
Arlington. Virginia 22209-8438 USA

To help the VITA Volunteer who answers your request, you should:

1. Be quantitative -- give measurements, costs, materials
available, sketches when possible.

2. Describe the best solution, if any, found nearby and
any limiting cultural factors.

3. Indicate a deadline for action. You will hear directly
from the VITA Volunteer; keep in contact with him; inform
the VITA Office if correspondence stops.


Volunteers in Technical Assistance (VITA) is
a private, nonprofit, international development
organization. Started in 1959 by a group
of concerned scientists and engineers, VITA
maintains an extensive documentation center
and worldwide roster of volunteer technical
experts. VITA makes available to individuals
and organizations in developing countries a
variety of information and technical resources
aimed at fostering self-sufficiency--needs
assessment and program development support;
by-mail and on-site consulting services;
information systems training. It publishes a
variety of technical manuals and manuals.