ABL(STEVENS)
Resin & Glass
Unit 4,
Millbuck Way, Springvale Industrial estate, Sandbach, Cheshire, CW11 3HT
Vinamold
(hot melt rubber)
INTRODUCTION
Vinamold Hot Melt Compounds are meltable vinyl compositions used for the
preparation of flexible moulds as alternatives to silicone rubbers,
polyurethanes, and rubber latex, in the casting of concrete, gypsum, polyester
resins and glass fibre laminates. Because vinamolds
are essentially craft materials, few tools and only simple equipment are
required. Once the behaviour of vinamold is understood, skill in producing even
complicated moulds is rapidly acquired. In use vinamold is melted by heating, poured over the article to be copied, then allowed to cool.
GRADES
AVAILABLE
For
identification purposes vinamold is supplied in different colours - yellow, Natural.
The 2 colours represent different hardnesses
(flexibilities): yellow is the hardest, natural softest.
Differences
between the 2 vinamold types can be summarised as:
Yellow:
Melting temperature 150-170°C (302-338°F).
Pouring
temperature 140-150°C(284-302°F).
Use: a)
where extremely thin sections are involved which could droop under their own
weight.
b) where large moulds are required which should not deform
under their own weight. The greater hardness of yellow vinamold minimises
deflection in a) and creep in b).
Natural:
Melting temperature 150-170°C (302-338°F). Pouring
temperature 140 150°C (284-302°F).
Use:
General purpose type, and for glass fibre reinforcement (GRP) laminates.
GENERAL PROPERTIES AND PRECAUTIONS.
Volume/weight relationship. For calculation purposes the specific gravity
of all vinamold grades may be taken as 1.0, so that 1 kg equals 1 litre, or 11b
equals 27.5 cu. ins.
Re-use.
Unlike some other flexible mould materials, vinamolds
are thermoplastic, that is to say they melt on heating and re-melt on
re-heating. Worn or obsolete moulds may therefore be cleaned and re-used many
times over, an obvious economic advantage.
DIMENSIONAL
STABILITY
Water.
Vinamold materials are not affected by water nor by
high humidity.
Temperature. Maximum ambient temperature 80°C (176°F).
Storage Life. Unused materials - indefinite. Moulds - many months,
subject to careful handling. Mould Surface Fidelity. Exceptionally fine detail
is possible.
Mould
Surface Durability. Depends on careful handling and fineness
of surface detail. The number of times a mould can be used may be as
many as 100.
Resistance to Solvents. Fine surface detail will be damaged by exposure to organic solvents
especially acetone, MEK, tetrahydrofuran, benzene, xylene and toluene. Many adhesives, paints, and paint
removers use such solvents.
Resistance to Detergents. For cleaning dusty mould surfaces detergents
should be well diluted. Strong detergents may extract some of the mould release
agents incorporated in the vinamold. Mould Lubrication. Generally the
lubricants incorporated in vinamold are sufficient. Additional lubricants, if
used should first be tested to ensure that no surface damage is likely to
occur.
Miscibility of Vinamold Grades. All grades are miscible in any proportions to
arrive at intermediate flexibilities.
Physical Form. 25 kg slabs.
MELTING
VINAMOLD
The more
care and control exercised in melting vinamold the more times the material can
be re used. Thermostatically controlled melters are
preferred. Alternative simple melters can be
constructed in the form of air or sand baths, utilising vessels (for example
cans) one inside the other with a gap all round of at least 12.5mm ('/2 in.).
It is recommended to restrict the volume of melted vinamold in these simple
devices to 5 kg (11 Ibs.). Under no circumstances
should oil be used in place of sand or air - hot oil can cause serious burns
and can easily ignite.
Whether
thermostatic or simple melters are used the practice
for melting is the same - cut the material into small pieces, melt a small
quantity, then add further pieces, melt these, add
more pieces and so on. Excessive fumes during melting indicate overheating
which will be followed by discolouration of the vinamold, and eventual
decomposition to a charred and unusable state.
MOULD
MAKING
There are
essentially 3 types of mould for which vinamold can be used:
A. Open
moulds for flat articles.
B. One part
moulds for simple non-flat articles.
C. Two part
moulds for complex articles.
For ease in
understanding the mould making descriptions, the various terms are defined:
Master. The original article which
it is desired to copy.
Replica.
A copy of the master.
Several
replicas may be used to simultaneously make a number of vinamold moulds for
quantity production.
Casting. The final article taken out of the
vinamold mould, made from concrete, gypsum, etc.
Wall. Raised part of an
open mould which decides the final area and depth of the mould.
Case. A container for the vinamold mould, designed to give support to prevent
distortion during the eventual casting process.
Cone Funnel. Device for pouring melted vinamold steadily into the mould cavity.
Typical proportions for a cone funnel - top opening diameter 1, bottom exit
diameter 0.5, height 3-6.
Riser. It is necessary to be sure that the mould cavity has completely filled,
the most positive means being a visual check. For this purpose a riser is
incorporated in the mould system to allow melted vinamold to fill the mould
then rise to a level as high as, or slightly higher than the top of the mould
cavity. The riser may be a simple hole in the top of the case but is preferably
a second cone funnel placed opposite the one used for filling. Melted vinamold
fills the first cone funnel, then the mould, then rises up the second funnel.
Pouring is stopped when the vinamold can be seen to have risen high enough.
Air Vents. Holes which allow air to escape
from the highest points in the mould cavity, so ensuring vinamold fills mould
cavity 100%. Air vent diameter minimum 3mm (1 /8 in.).
Mould Cavity. The space
between the master or replica, and the wall (or case). Equivalent to the
vinamold mould mass.
Register. The two halves of a split mould
must fit together perfectly to prevent the final article exhibiting the effects
of misalignment. When the halves match 100% they are said to be registered. A
means of assuring this is by the use of pins, pegs or other register devices on
one part of the mould case, which locate into matching holes or depressions in
the other part of the mould case.
Guides. Pins or pegs in one part which fit
into corresponding pockets, rings, sleeves, or holes in the second part to
ensure register of a two part mould.
A. OPEN
MOULD
For the
production of gypsum ceiling tiles, concrete paving slabs, concrete
commemorative plaques and decorative features (e.g. bank emblems) in bas-relief
or high relief.
Step 1.
Fix master or replica on a flat board.
Step 2.
Using clay, wood or other suitable medium make a wall all round 25mm (1 in.)
higher than the highest point of the master/replica. Depending on the
proportions of the master/replica leave a space of from 25mm (1 in.) to 150mm
(6 in.) all round between the wall and master.
Step3. Pour
melted vinamold slowly and steadily over the master/replica until level with
the top of the containing wall.
Step 4.
Leave 8 hours to cool.
Step5. Lift
the vinamold mould carefully off the master and turn over. Note: For
convenience in handling make a box round the vinamold mould. The mould is ready
for use.
B. ONE PART
MOULD
For the
production of concrete building components; bollards; simple animal/human
figures in gypsum; pre-production samples in polyester resin etc.
Step 1. Secure master/replica on a base board.
Step 2. Cover master/replica in clay to a
thickness of about 20mm (% in.). The clay represents the thickness of the final
vinamold mould i.e. the mould cavity.
Step 3. Using gypsum reinforced with hessian, or polyester reinforced with glass fibre, build up
a case of a suitable thickness relative to the size of the master/replica (up
to 25mm/1in.) incorporating a fixing flange (see Step4) and allow to set. Mark
position of case on base board.
Step 4. Remove case and extract all the
clay. Return case to pre-marked position on base board and fix down with
screws, bolts etc., through fixing flange.
Step 5. Remove case from base board and
prepare case with 2 (minimum) cone funnels by making holes 25-50mm diameter as
near base board level as practicable. Cone funnel holes should be opposite each
other, or equi-spaced if
more than 2. Height of the funnels must be such that filling and riser funnels
will level at about 150mm (6 in.) above the highest point of the mould cavity.
The cone funnels should, of course, be tight fits in the entry/riser holes in
the case to prevent leakage of molten vinamold during filling.
Depending
of complexity the cavity should be provided with air vents, one at the
uppermost point at each part of the cavity.
Step 6. Pour vinamold slowly and steadily
to prevent air bubbles entering and causing porosity in the mould. Air should
dissipate back through the filling cone funnel. When vinamold is seen to be
flowing out of the air vents these should be plugged to prevent unnecessary
spillage. Stop pouring when vinamold fills all funnels.
Step 7. Allow to cool for 8 hours.
Step 8. Pull out cone funnels, cut off
vinamold at entry/riser holes. Remove case, mould, and master/ replica, leave
vinamold in case.
The mould
is ready to use.
C. TWO PART
MOULD (
For the production of statuettes, busts, complex technical articles.
Step A. Select natural plane(s) (vertical, horizontal,
diagonal or combination) along which to split the mould.
Step B. Follow Steps 1 - 7 as for one part mould, to
make first part as far as selected split line.
Step C. Plan register and guide pin system, then support
first part in a convenient position. Repeat procedure to Step 3 as for one part
mould, incorporating register system. Apply release agent to glass fibre edge.
Step D. Again follow Steps, 4, 5, 6, 7 described for
one part mould. After removing clay (Step 4 -one part mould) treat first
vinamold surface with release agent - talc or shellac.
Step E. Separate mould parts, remove master/replica.
Step F. With reference to the master/replica, select
and make a hole at the most appropriate (concealed)
position through which to fill the mould with gypsum, concrete etc., and the
best attitude (angle) for mould filling.
Step G. Fill mould, allow to set and
check for air entrapment. Provide air vents as indicated.
CORRECTION
OF VINAMOLD MOULD FAULTS
Small
faults, due to air bubbles, tears, or deficiencies in the master, can be
corrected by carefully touching up with a hot blade. Small pieces of vinamold
can be fused into the mould surface to take up cavities.
PREPARATION
OF MASTERS
N.B. If a
Master Is rare, valuable, or delicate take extra care in Sealing and
Pre-warming. If in doubt as to the possible effect of sealing materials or heat
please consult us. We will advise you to the best of our ability, but we can
accept no responsibility for damage to masters howsoever caused.
Porous Dry Clay or Gypsum. Seal surface*.
Wood.
Experiment with surface sealer*. Epoxy resin may be used as a sealer to prevent
bubble formation in vinamold due to air and moisture from the wood.
Concrete or Stone. Fill pores by soaking with water. Allow surface to dry superficially
prior to pouring vinamold.
Metal. No
sealing is necessary. A thin film of mineral or vegetable oil will facilitate
removal from the vinamold.
Porcelain and Glass. Carefully pre-warm to prevent breakage when vinamold is poured over the
masters.
Clay. (Modelling or Natural). No preparation needed.
GRP. Pre-heat for 30-60 minutes
at 30-40 C° (80-100°F) to ensure full cure and freedom from volatiles.
EXAMPLES OF
APPLICATIONS FOR VINAMOLD HOT MELT COMPOUNDS
Construction
Industry Prefabricated concrete panels. Decorative panels, coats-of-arms,
company emblems. Interior Decoration Ceiling and wall
embellishments - patterns, cornices, friezes. Period decorative effects
- furniture, mirror surrounds. False beams; wood, stone, and
brick simulation panels. Doors, plaques, armorial crests. Especially
effective in bronze and aluminium filled polyester resins. Suspended
ceiling, acoustic and thermal insulating tiles.
Used in
homes, bars, restaurants, hotels, banks, ships' saloons, civic buildings,
colleges, etc.
Tourist
Souvenirs Replicas of antique items, figurines, doll
heads, masks, historical replicas. Educational/Museums/Arts and Crafts
Three
dimensional topographical maps, biology models, sculpture replicas, fossil
casts.
Some more
unusual applications of vinamold are in life-size human figures, utilising the
flesh-like consistency of the material.
The
information contained in this leaflet is to the best of our knowledge true and accurate.
However, since the conditions under which our products may be used are beyond
our control, recommendations are made without warranty or guarantee.