PolyCast Acrylic -- Material of a thousand uses.
Polycast acrylic sheet is a material with unique physical properties and performance
characteristics. It weighs half as much as the finest optical glass, yet is equal to
it in clarity and is up to 17 times more impact resistant. It can be worked as easily
as wood, can be formed into endless, interesting and functional shapes, is resistant
to chemicals and industrial fumes, and remains stable under sustained exposure to the
elements. Polycast sheet is made in over 250 colors, in thicknesses from .030" to 4.25'
and can transmit ultraviolet light or filter it out, as required. Aircraft
manufacturers use Polycast sheet in jets and helicopters. Bullet-resisting Polycast
sheet helps solve security problems for banks and stores. Because of its light and
energy transmission properties architects find Polycast ideal for skylights, sun
screens, fascia panels and dome structures. Polycast material is a favorite medium
of furniture designers and sculptors. Retailers show off their merchandise in displays
made from Polycast sheet, while signs made from Polycast sheet light up the nation.
Its impact resistance makes Polycast sheet an outstanding glazing material. It is
used in home furnishings, chair mats, lighting fixtures, safety equipment, decorating
panels, office partitions and appliances of all kinds. And it's a favorite material
of the do-it-yourself hobbyist.
Weatherability: Polycast acrylic sheet has exceptional weathering characteristics.
Clear sheet will not yellow even after long years of exposure to sunlight, and
colors won't fade.
EXPANSION AND CONTRACTION:
Like most plastics, Polycast acrylic sheet responds to temperature changes by expanding
or contracting at a far greater rate than glass When using Polycast acrylic sheet for
outdoor glazing, cut the sheet approximately 1/16" per running foot shorter than the frame size.
Polycast acrylic sheet is much more flexible than glass or many other building materials. When using large sheets for windows, it is important that rabbets
or channels be deep enough to provide support against high winds.
Polycast acrylic sheet has excellent resistance to attack by
many chemicals. It is affected, in varying degrees, by benzene, toluene, carbon
tetrachloride, ethyl and methyl alcohol, lacquer thinners, ethers, ketones and esters.
Polycast acrylic sheet is an excellent insulator. Its surface
resistivity is higher than that of most plastics. Continuous outdoor exposure
has little effect on its electrical properties.
Colorless Polycast acrylic sheet has a light transmittance of 92%.
It is clearer than window glass and will not turn yellow. Translucent white Polycast
acrylic sheet diffuses light smoothly and evenly, so it's excellent for all types of
lighting fixtures and signs. Polycast acrylic sheet is also available in a large
variety of transparent and translucent colors.
All acrylic sheet is combustible. Self-ignition temperature range
is 830-860"F. Protect it from flames and high heat.
Wash Polycast sheet with a mild soap or detergent and plenty of lukewarm water.
Use a clean soft cloth, applying only light pressure. Rinse with clear water
and dry by blotting with a damp cloth or chamois. Grease, oil or tar may be removed
with a good grade of hexane, aliphatic naphtha, or kerosene. These solvents may be
obtained at a paint or hardware store and should be used in accordance with
manufacturers' recommendations. Any oily film left behind by solvents should be
removed immediately by washing.
DO NOT USE: Window cleaning sprays, kitchen scouring compounds, or solvents such
as acetone, gasoline, benzene, carbon tetrachloride or lacquer thinner.
Static electricity can attract dust to Polycast acrylic sheet. To reduce it, use
an anti-static cleaner which is available from San Diego Plastics. Or consider using an
inexpensive anti-static gun, such as those commonly sold in Audio stores for removing
static from phonograph records.
Polycast acrylic sheet comes covered on both sides with a low-tack masking paper.
It is also available with a thick-polyethylene film with a low-tack adhesive
(Polymask) or with a thin polyethylene film without adhesive (unmasked). The masking
protects the sheet from scratching during storage and handling. Be sure to leave the
masking in place during all phases of fabrication and installation. Except for intricate
detail work, you should remove the masking only when project is completed.
You can remove the masking paper with a cardboard tube -- rolling the paper around it.
All papermasked Polycast sheet should be kept away from heat, sunlight and water.
This is not true of Polymask sheet. Masking should be removed soon after installation.
Important Do's and Don'ts:
* Keep meshing on as long as possible through fabrication operations.
* Always wear safety glasses when working with power tools.
* Use metal-cutting saw blades and drills which are ground for acrylic sheet.
* Make certain all your tools are sharp.
* Use water or an appropriate drilling oil as a coolant when cutting sheets
over 1/8" thick or drilling sheets over 3/16" thick.
* Use the proper thickness for glazing blanks.
* Allow 1/16" per linear foot for expansion in glazing applications.
* Wet the surface of Polycast acrylic sheet before cleaning.
* Ask San Diego Plastics for detailed information.
* Don't store Polycast acrylic sheet near radiators or steam pipes or in direct sunlight.
* Don't remove the masking until all work is finished.
* Don't install large sheet with bolts. Frame them.
* Don't mark with a punch marker.
* Don't use saw blades having side-set teeth. Saw teeth ideally should be ground
with zero degree rake and be of uniform height and shape.
* Don't bring the material in direct contact with heaters.
* Don't subject sheet to high surface temperatures during polishing.
* Don't use glass-cleaning sprays, scouring compounds or solvents like acetone, gasoline,
benzene, carbon tetrachloride, or lacquer thinner on acrylic sheet.
* Don't heat Polycast acrylic sheet in a kitchen oven.
* In hot weather, don't store masked acrylic sheet in direct sunlight.
Polycast acrylic sheet can be cut in many ways with hand tools or power tools.
The method you choose will likely depend on the tools available to you. But all
tools cannot be used in all cases. Your choice of tool and technique should also
be based on the thickness of the sheet, and the shape of the particular cut.
This section, though not comprehensive, gives some guidelines for choosing the right
method and getting the best results with Polycast acrylic sheet.
CUTTING WITH KNIFE OR SCRIBE:
Polycast acrylic sheet up to 3/16" thick may be cut by a method similar to that used
for cutting window glass. Use a scribe of some kind -- a scribing knife, a metal
scribe, an awl, or even a sturdy craft knife -- to score the sheet. Draw the scriber
several times (7 or 8 times for a 3/16") thick piece) along a straight edge held firmly
in place. It is best not to remove the protective masking. Make the cuts carefully using
firm, even pressure. For best results make each stroke cleanly off the edge of the sheet.
Then, clamp the Polycast acrylic sheet or hold it rigidly under a straight edge with the
scribe mark facing up and hanging just over the edge of a table. Protect your hands with
a cloth, and apply a sharp downward pressure to the top side of the sheet. It will
break along the scratch. Scrape the edges to smooth any sharp corners. This method
is not recommended for long breaks or thick material.
CUTTING WITH POWER SAWS:
Blades used to cut Polycast acrylic sheet should be sharp, and free from nicks and burrs.
Special blades for cutting acrylics are available for most types of saws. San Diego
Plastics has them in stock. Otherwise, use blades designed
for cutting metals (especially aluminum or copper); they work well. Teeth should be fine,
of the same height, evenly spaced, and with little or no set.
Table saws and circular
handsaws: Use hollow ground, high-speed blades with no set, and at least 5 teeth per inch,
such as those used to cut copper and aluminum. If you intend to do extensive cutting, carbide
tipped blades, although more expensive, will last longer without sharpening (a triple chip
type tooth design is recommended). They also tend to give a cleaner cut in acrylic sheet.
Set the blade to project approximately 1/8" above the surface of the sheet being cut.
This will reduce edge chipping. When cutting with a hand-held circular saw, clamp the sheet
securely to the work surface to minimize vibration. A wood block 1" x 3" clamped on top of
the sheet spreads the clamping force and can act as a guide for the saw.
No matter which type of saw you use, the sheet must be held firmly and fed slowly and
smoothly to prevent chipping. Lubricating the blade with beeswax or a bar of soap will help
keep the masking adhesive from gumming up the blade. Be sure the saw is up to full speed
before beginning to cut. Water-cooling the blade is suggested for thicknesses over 1/4"
especially when edge cementing will be performed.
Saber saws: Use blades which have a slight set, such as the blades recommended for cutting
metals or other plastics. Be sure they are sharp. The blades you use for cutting acrylic
should never be used to cut other materials. Set them aside. Use them only for acrylic sheet.
High speed is best for cutting Polycast acrylic sheet with a saber saw. Always be sure the
saw is at full speed before beginning to cut. Press the sawshoe firmly against the material,
and don't feed too fast. Water cooling is suggested for cutting acrylic sheet over 1/4" thick.
Band saws or jig saws: Band saws and jig saws are excellent tools for cutting Polycast
acrylic sheet. But because of their relatively thin blades they are not recommended for
cutting acrylic sheet over 1/4" thick. Use blades with a slight set and about 10 teeth per
inch. Feed acrylic sheet at a rate 10 times faster than you would feed steel. Blades may
break easily in acrylic, so operate accordingly.
CUTTING WITH HAND SAWS:
Almost any type of hand saw may be used to cut Polycast acrylic sheet. And while good
results are possible with hand saws, the techniques involved are considerably more difficult
than with power saws. Practice on scrap material before attempting to make critical cuts.
With any hand saw, it is most important that the blades be kept sharp. For best results, the
teeth should be of uniform size and shape, and have very little set. Every effort should be
made to prevent vibration or stress while cutting. Flexing at the point of the cut or
binding of the saw blade may cause the acrylic to crack. Clamp the material securely. Keep
the saw straight when cutting, and apply very little pressure. Let the blade do the work.
With practice and proper care, you can get good results.
Straight Saws: Straight saws or crosscut saws may be used for long, straight cuts on
Polycast acrylic sheet of almost any thickness. The saw should have a hollow-ground blade
with very little set and at least 10 teeth per inch. Make certain the material is firmly
clamped and supported. Hold the saw at an angle of about 45° from vertical, and be
sure to keep it straight.
Coping Saws: Coping saws or scroll saws are good for shorter cuts, curved cuts, or even
intricate designs. Use very narrow blades with only a slight set.
Hacksaws or Keyhole Saws: These hand saws for cutting metal may also be used for short
cuts in Polycast acrylic sheet. Choose a blade with approximately 18 teeth per inch.
Use a smooth, even stroke. Apply very little pressure.
ROUTING AND SHAPING:
Polycast acrylic sheet can be machined with standard woodworking routers in much the
same way as wood. You'll find many uses for portable hand routers and small table routers.
Use them to cut patterns into edges, or larger holes out of pieces of Polycast
For best results, use single-fluted bits for inside circle routing and double-fluted
bits for edge routing.
Routers are designed to operate at high speeds:
10,000 to 20,000 rpm is recommended for Polycast acrylic sheet. And because routing
speeds are so high, vibration must be scrupulously avoided. Even small vibrations can
cause crazing and fractures in acrylic sheet during routing. San Diego
Plastics sells router bits for plastics!
Turning is the only practical way to produce most round cross-sectioned parts such as
knobs, furniture legs, and vases. Polycast acrylic sheet can be turned on almost any
type lathe. Bits designed especially for cutting acrylic are available. But most
high-speed tool bits with a zero-degree, or slightly negative rake will work very well.
It is essential that rake be maintained at 0 to -4° for satisfactory results.
Clearance angles should be from 5 to 10°. Use a turning speed approximately 10
times faster than for wood. You should be able to get a continuous chip from the Polycast
Polycast acrylic sheet may be drilled by any kind of hand or power drill. A stationary
drill press is the preferred tool because it gives better control and greater
accuracy. But a drill press won't be applicable in all instances, and with a little care,
proper technique, and a correctly-ground drill bit, you can get good results with an
ordinary hand drill.
For best results use drills designed specifically for acrylics. They are available from
San Diego Plastics. We can help you select the drills that are best for your job.
Regular twist drills can be used, but the cutting edges must be modified to prevent the
blade from grabbing and fracturing the plastic. Polycast acrylic sheet is relatively soft.
Your drill should have an edge that cuts with a scraping action. To obtain this, you
can modify your drill bit by grinding small "flats" onto both cutting edges with a medium
or fine-grit grinding wheel, or a pocket stone. The flats can be parallel to the length of
the drill and about 1/32" wide. Tip angle should be between 60 and 90°. For the
best possible finish inside the hole, use a drill with smooth, polished, slow-spiral flutes
which will clear the hole of all shavings without marring or burning the walls.
If the drill is correctly sharpened and operated at proper speed, two continuous spiral
chips or ribbons will emerge from the hole. When drilling a hole three times deeper than
the diameter of the drill, a lubricant or coolant should be used. This will help remove
chips, dissipate heat, and improve the finish of the hole. Rough, irregular, or fuzzy
holes can lead to cracking and breaking months after the piece has been completed.
It is necessary to smooth and square the edge of the sheet which has been cut. This is
because cutting by any technique will leave a rough edge that is usually unsuitable either
as a finished edge or to join to another piece of acrylic. You can do this by a number of
different techniques, depending on the finish desired. The first step, and perhaps easiest
technique, is scraping. A scraper can be almost any piece of metal with a sharp, flat edge.
The back of a hacksaw blade, the back of a knife blade, or a tool steel blank are ideal.
Special tools for scraping acrylics are also available from San Diego Plastics.
Whatever tool you use must have a sharp, square edge.
It is easy to file Polycast acrylic sheet to a surface ready for final polishing.
The filing, however, must be done correctly and carefully. Almost any commercial file can
be used. But the quality of the finish will depend on your choice of file coarseness.
A 10 to 12 inch smooth-cut file if recommended for filing edges and removing tool marks.
Other files -- half round, rat tail, triangular files, and even small jewelers' files --
are good for smoothing insides of holes, cutting grooves and notches, or finishing detail.
File in only one direction. Keep the teeth flat on the surface of the Polycast acrylic sheet,
but let the file slide at an angle to prevent the teeth from cutting unwanted grooves in your
work. Always keep your files clean and sharp. Wire brush them often to prevent the teeth from
filling up. And don't use your acrylic files for working metal or other materials that might
dull the teeth. For small work, try clamping the file in a vise and rubbing your work across
Before Polycast acrylic sheet is ready to be polished, it should be sanded to a smooth,
satiny finish. As with filing, the quality of the final finish will depend on the grades
of sandpaper used. The finer the final grit, the smoother the finish. It will usually take
at least three steps to get a good finish. If there are scratches deep enough to require it,
start with coarse grit No. 60 sandpaper. Use it dry. When the original scratches are
completely removed, sand with a medium grit paper - 220 is good - to remove the scratches
from the coarse paper. Use the medium grit paper dry as well. Finally, sand to a satiny
finish with a fine grit, wet-or-dry No. 400 paper. Fine grit paper should always be used
wet to keep the paper from clogging and obtain a smoother finish. Rinse the paper frequently.
Grits as fine as 600 may be used. Always wipe your work clean when changing to a finer grit.
Be sure all deep scratches have been removed .
Sanding by Hand: Hand sanding Polycast acrylic sheet is very much like hand sanding wood.
Most of the same techniques apply. But sanding acrylic must be done with far greater care.
You should always use a wooden or rubber sanding block. When removing scratches, be sure to
sand an area that is slightly larger than the scratch. This will help prevent low spots.
Sand with a circular motion. Use light pressure and plenty of water with wet-or-dry papers.
As you get the feel of working with Polycast acrylic sheet, your own observations and
experience will be your best guide to determining how coarse a grade to start with on each
particular job and how many different grades will be needed to do the job most efficiently.
Don't be afraid to experiment with different sanding techniques and different types of blocks.
You'll learn a lot of new tricks -- perhaps the very one you'll need to help solve your next
Sanding with power sanders: Almost any commercial power sander can be used to work
Polycast acrylic sheet. Naturally, different types of sanders are preferred for different
operations. As a basic rule, use them as you do when sanding wood. They should, however, be
operated with lower pressure, and at slower speeds. Experiment on scrap pieces. All wet-
or-dry machine sanding should be done wet especially with grit sizes of 150 or finer.
The original high luster of Polycast acrylic sheet can be restored to the edges and surfaces
by polishing with a power driven buffer. It is quite possible to polish Polycast acrylic
sheet by hand using a soft cloth and a very fine abrasive. But hand buffing is an extremely
tedious process. You're likely to get a sore arm long before you get a finely polished
surface. Power-driven buffing tools are recommended almost without exception.
Because inexpensive buffing wheels are available as an attachment for any electric drill,
equipment should not be a problem.
Buffing wheels and compounds good for acrylics are sold by San Diego Plastics, but
special wheels are not really necessary. A good buffing wheel for Polycast acrylic sheet
will consist of layers of 3/16" carbonized felt or layers of unbleached muslin laid together
to form a wheel between 1 and 3 inches thick. The larger the wheel, the better.
Caution: Don't use one too large for your equipment. The wheel should reach a surface speed
of at least 1200 feet per minute. Speeds up to 4000 feet per minute are useful for acrylics.
Solidly stitched wheels with rows of concentric stitching should be avoided. They are often
too hard and may burn the acrylic. Never use a wheel that has been used to polish metal.
Traces of the metal may remain to scratch the Polycast acrylic sheet.
Polycast acrylic sheet should be polished using a commercial buffing compound of the type
used for polishing softer metals such as silver or brass. Or you can use a non-silicone
car polish that has no cleaning solvents in it. First, however, tallow should be applied to
the wheel as a base for the buffing compound. Just touch the tallow stick to the spinning
wheel. Then, quickly apply buffing compound. To polish, move the piece back and forth across
the wheel until you get a smooth, even polish. Be careful not to apply too much pressure.
Keeping the work constantly moving across the wheel will help prevent heat buildup which
can mar the surface by burning or smearing. It also prevents overheating that will later
develop into stress craze. For safety reasons, it is important not to start polishing near
the top of the sheet. The wheel may easily catch the top edge, tearing the piece of Polycast
accylic sheet out of your hands and throwing it across the room . . . or at you. Always
wear safety glasses and be extremely careful. Begin polishing approximately one-third of
the way down the sheet, and keep moving it back and forth until you've reached the bottom
edge. Then turn the sheet around and repeat the process on the other half.
When heated above 275"F Polycast acrylic sheet becomes soft and pliable, almost like a
sheet of flexible rubber. It may then be formed into almost any shape. As the sheet cools,
it hardens and retains the formed shape, provided it has been held in place during the
cooling process. Do not exceed 360° F for more than one hour. Excessively high
temperatures may cause the sheets to blister and burn. Never heat Polycast acrylic
sheet in a kitchen oven. Acrylic sheet gives off highly flammable fumes when decomposed
by overheating. These gases are potentially explosive if allowed to collect in an
unventilated area. Most kitchen ovens do not have accurate temperature controls.
Temperatures can be off as much as 75°, possibly allowing the acrylic to
overheat. Because air is not forcibly circulated in a standard kitchen oven, the fumes
will accumulate. When they come into contact with the heat source there is likely to be
an explosion. Repeat: Do not heat acrylic in a kitchen oven.
FORMING WITH A STRIP HEATER:
A strip heater is the most useful acrylic-forming device in the home craftsman's arsenal.
Used properly, it is perfectly safe. A correctly assembled strip heater will not exceed
safe heat. Unfortunately, a strip heater can only be used to form straight-line bends.
It will allow you to make those bends with a minimum of trouble -- and a minimum of
A strip heater heats only the area to be formed -- there's no need to heat the entire
sheet if you only intend to make a straightline bend. It heats quickly. And with a little
care you'll get excellent results, because the rest of the piece stays cool. Strip heater
kits with complete instructions are available from San Diego Plastics.
Heating and forming Polycast acrylic sheet with a strip heater is not difficult. When
properly heated, the acrylic may be easily bent into smooth, clean corners. With patience
and a little practice you will achieve excellent results. First, remove the masking paper
from the line of the bend. The rest of the mashing paper should be left in place to protect
the unheated area. Then, lay the sheet on the heater with the bend line directly above the exposed heating element so that the bend will be
made away from the heated side. The length of heating time will vary according to the
thickness of the sheet. Polycast acrylic sheet thicker than 3/16" should be heated on both
sides for a proper bend. Heat the sheet until it begins to sag at the bend line. Don't try
to bend the sheet before it is fully heated, or after it has partially cooled. This will
result in irregular and creased corners and high internal stress. Heat the bend line very
carefully. Uneven heating can cause bowing along the line of the bend. Sometimes this is
difficult to avoid -- especially with pieces over 24" long. Bowing can be minimized, however,
by holding the just-formed material in a clamp or jig until it has cooled. Forming jigs and
clamps should be used for best results. They can be very simply made of wood and used over
and over. Make preformed jigs for certain angles or even special shapes for individual
projects. Variable angle jigs can be made with two pieces of wood hinged together and held
at the desired angle with a variable brace. Felt, flannel, or flocked rubber
should be used to line any surfaces that may come into contact with the heated acrylic.
Wear heavy cotton gloves when handling heated Polycast acrylic sheet. They'll protect your
hands, as well as the sheet.
OTHER FORMING TECHNIQUES:
Polycast acrylic sheet may be formed into almost any shape. But
specialized heating and forming equipment is usually required for all but the simplest
projects. And while many of the forms and jigs required for two and three dimensional
forming can be easily made out of wood in the home shop, such projects are beyond the scope
of this document. However, many excellent books are available covering all types of acrylics
forming. They deal with techniques such as drape forming, plug and ring forming, surface
molding, blow and vacuum forming, and even design, construction, and use of ovens for
heating acrylic sheet.
Except for certain specialty acrylics, Polycast acrylic sheet can be joined with solvent
cements to form strong, durable, transparent joints. But the ultimate strength and
appearance of your joints will depend on how carefully you make them. Getting really good
joints requires a lot of care and considerable skill. Practice on scrap pieces.
The more experience you have, the better your work will be.
Basic cautions to observe when working with acrylic solvents:
* Always work in a well-ventilated area.
* Do not smoke -- solvents are highly volatile and may be flammable.
* Protect skin from contact with cement and solvents.
* Do not attempt to cement Polycast acrylic sheet in temperatures under 60° F.
Temperatures from 70" to 75"F are ideal.
* Always follow the cement manufacturer's recommendations.
PREPARATION OF THE JOINT:
All surfaces that are to be joined should fit together accurately without having to be
forced. Flat, straight surfaces are easiest to work with. Any area that is part of the
original surface of the sheet should be left untouched. A smooth cut made with a cooled
power saw also should be left alone. These surfaces need no additional preparation.
But if the area to be joined has a saw cut that is rough, it should be wet sanded or
finished with a joiner or shaper to get a perfectly flat, square edge. Do not polish
edges that are to be cemented. Polishing leaves a convex edge with rounded corners.
It will make a very poor joint. Always remove the masking material from around the
area to bejoined.
Polycast Poly 76 and Poly 84 require two-part polymerizable cements. Contact us
for further information.
Capillary cementing is probably the most popular method of joining Polycast acrylic sheet.
It works because of the ability of a low-viscosity solvent-type cement to flow through a
joint area by capillary action. Properly done, it yields strong, perfectly transparent
joints. But capillary cementing won't work at all if the parts do not fit together perfectly.
Solvents and cements are available from San Diego Plastics. We can recommend the ones that
are best for your particular projects.
First make sure the parts fit together properly. Then join the pieces together with masking
tape. Or clamp them to a form that will support the pieces and hold them firmly in place.
It is important that the joint be kept in a horizontal plane, or the cement will run out of
the joint. Apply the cement carefully along the entire joint. Apply it from the inside edge,
whenever possible on a box-corner type joint, and from both sides, if possible, on a flat
piece. A special needle-nozzled applicator bottle (available from San Diego Plastics is
If the cement does not flow completely into the joint, try tilting the vertical piece
very slightly (about 1") towards the outside. This should allow the solvent to flow freely
into the entire joint. Always let the joint dry throughly before removing tape or clamps.
Maximum bond strength will not be reached for 24 to 48 hours.
DIP OR SOAK CEMENTING:
This method of cementing Polycast acrylic sheet involves dipping the edge of one of the
pieces to be joined directly into the solvent. It is very important that only the very
edge be dipped. Exposing too much area to the solvent will result in a weak, slow-setting
point. You'll need a shallow tray in which to dip the acrylic. The tray can be made of
aluminum, stainless steel, galvanized steel, or glass. Do not use plastic, the solvent may
Place short pieces of wire, pins, or brads into the tray to keep the edge of the Polycast
acrylic sheet from touching the bottom of the tray. The tray must be almost perfectly level.
Pour solvent cement into the tray so that it just covers all the brads and covers them evenly.
Now, carefully place the edge to be cemented into the tray so that it rests on the brads.
You can hold the piece upright by hand, but it is better to use some kind of support to hold
the piece in place while it soaks. A couple of padded clamps attached to the sheet, and
resting on the edge of the tray are fine. Heavy pieces of wood placed against each side of
the sheet will also work. Slotted wooden supports are usually used for production work, but
anything that will hold the piece firmly upright is sufficient.
The Polycast acrylic sheet should be left in the solvent from 1 to 2 minutes, depending on
the thickness of the sheet, the type of solvent used, and the bond strength required.
Soaking time should be long enough to allow the edge of the sheet to swell into a
"cushion" As soon as an adequate cushion is formed, the piece must be removed. Hold it for
a few seconds at a slight angle to allow the excess solvent to drain off. Then carefully,
but quickly, place the soaked edge precisely into place on the other part to be joined.
Hold the parts together for about 30 seconds without applying any pressure. This will allow
the solvent to work on the surface of the other piece. After 30 seconds you can apply some
pressure to squeeze out any air bubbles. But be very careful not to squeeze out the cement.
When the pieces are joined, the part should be placed in a jig or clamp to maintain firm
contact for 10 to 30 minutes. Do not allow the parts to move during this critical time.
Allow the joint to set for another 8 to 24 hours before doing any further work on it.
Viscous cements are used to cement joints that can't be easily cemented by capillary or
soak solvent methods -- either because they are difficult to reach, or because the parts
don't fit properly together. Viscous cement is thick. It will fill small gaps, and can make
strong, transparent joints where solvent cements can't. Viscous cements are available from
San Diego Plastics. Or you can make your own viscous cement by dissolving chips of clear
Polycast acrylic sheet in a small amount of solvent. Let the solution stand overnight.
Remove the masking material from around the joint area, and carefully apply a small bead
of cement to one side of the joint. Then gently join the pieces as described under
"Soak Cementing" Masking tape may be applied to protect the area around the joint.
But it should be removed carefully after about 5 minutes, while the cement is still wet.
Don't touch the parts at all for the first critical 3 minutes, or the joint will not hold.
The part may be carefully moved after 10 minutes, but don't do any additional work on it
for 12 to 24 hours.
Superior joints are achieved using polymerizable, or "two part" cements. These cements
must be mixed prior to use and must be used immediately, as they "set up", or harden.
Instructions on the use of these cements may vary from manufacturer. Contact San Diego
Plastics for more information.
Polycast acrylic sheet is lighter, more transparent, and far more break resistant than
glass. Thus glazing with Polycast acrylic sheet is safe and easy. Important: Polycast
acrylic sheet expands and contracts at a much greater rate than glass. To compensate,
remember to allow approximately 1/16" per running foot shorter than your frame size.
The sheet thickness you need depends on the size of your window.
For windows smaller than 24", use an elastic glazing compound which is compatible with
acrylic sheet. For windows over 24': it is important that you select the proper rabbet
depth to allow for expansion and contraction.
Up to 24" x 36"--------1/2 to 5/8"
Up to 36" x 48"--------5/8 to 3/4"
Up to 48" x 72"--------3/4" to 1"
Use a continuous removable stop, and caulk with a polysulfide sealant or butyl tape.
If it is necessary to bolt a small panel to a frame, drill mounting holes larger than
the diameter of the bolts or screws. Use round-head screws with rubber washers against
the Polycast acrylic sheet and stainless steel washers against the screw head. After
tightening, back off 1/2" turn. Do not use counter-sunk, flat-head screws. They
will fracture the acrylic sheet.
Polycast acrylic sheet should be protected from flames and high heat because it
is a combustible material. This thermoplastic usually burns rapidly to completion
if not extinguished. The products of combustion are carbon dioxide and water if
sufficient air is present. If not, toxic carbon monoxide will be formed. Users
should follow building codes and exercise good judgement in the use of this material.
Access panels may be required for evacuation of areas glazed with Polycast acrylic
sheet. The combustibility properties of Polycast acrylic sheet can be described
by the following - Self Ignition Temperature by ASTM D 1929 for Polycast acrylic
sheet is 860° F. Rate of burning 1/8" thickness as measured by ASTM D 635
is 1.0 inches per minute. Smoke density as measured by ASTM D 2843 is 3% to 15%.
While this text data is based on small-scale laboratory tests frequently referenced
in various building codes, these tests do not duplicate actual fire conditions.
The information and statements herein are believed reliable but are not to be
construed as a warranty or representation for which POLYCAST or SAN DIEGO PLASTICS,
INC. assume legal responsibility. Users should undertake sufficient verification
and testing to determine the suitability for their own particular purpose of any
information or products referred to within this document. No warranty of fitness
for a particular purpose is made. Nothing within this document is to be taken as
permission, inducement or recommendation to practice any patented invention
without a license.
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