VINAMOLD (hot melt rubber)
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.
identification purposes vinamold is supplied in different colours -
yellow, Natural. The 2 colours represent
2 different hardnesses (flexibilities): yellow
is the hardest, natural softest.
between the 2 vinamold types can be summarised as:
Melting temperature 150-170°C (302-338°F).
Use: a) where
extremely thin sections are involved which could droop under their own
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).
Melting temperature 150-170°C (302-338°F). Pouring temperature 140
purpose type, and for glass fibre reinforcement (GRP) laminates.
PROPERTIES AND PRECAUTIONS.
relationship. For calculation purposes the specific gravity of all 3
vinamold grades may be taken as 1.0, so that 1 kg equals 1 litre, or 11b
equals 27.5 cu. ins.
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.
Vinamold materials are not affected by water nor by high humidity.
Maximum ambient temperature 80°C (176°F).
Unused materials - indefinite. Moulds - many months, subject to careful
handling. Mould Surface Fidelity. Exceptionally fine detail is possible.
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.
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.
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
of Vinamold Grades. All grades are miscible in any proportions to arrive
at intermediate flexibilities.
Form. 25 kg slabs.
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.
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.
essentially 3 types of mould for which vinamold can be used:
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
The original article which it is desired to copy.
A copy of the master.
replicas may be used to simultaneously make a number of vinamold moulds
for quantity production.
The final article taken out of the vinamold mould, made from concrete,
Raised part of an open mould which decides the final area and depth of the
A container for the vinamold mould, designed to give support to prevent
distortion during the eventual casting process.
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.
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.
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.).
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.
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
A. OPEN MOULD
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.
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.
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
production of concrete building components; bollards; simple animal/human
figures in gypsum; pre-production samples in polyester resin etc.
Secure master/replica on a base board.
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
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.
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.
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
complexity the cavity should be provided with air vents, one at the
uppermost point at each part of the cavity.
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.
Allow to cool for 8 hours.
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 (SPLIT MOULD)
production of statuettes, busts, complex technical articles.
Select natural plane(s) (vertical, horizontal, diagonal or combination)
along which to split the mould.
Follow Steps 1 - 7 as for one part mould, to make first part as far as
selected split line.
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.
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.
Separate mould parts, remove master/replica.
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.
Fill mould, allow to set and check for air entrapment. Provide air vents
VINAMOLD MOULD 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.
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.
Clay or Gypsum. Seal surface*.
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
Stone. Fill pores by soaking with water. Allow surface to dry
superficially prior to pouring vinamold.
sealing is necessary. A thin film of mineral or vegetable oil will
facilitate removal from the vinamold.
Glass. Carefully pre-warm to prevent breakage when vinamold is poured over
(Modelling or Natural). No preparation needed.
Pre-heat for 30-60 minutes at 30-40 C° (80-100°F) to ensure full cure and
freedom from volatiles.
APPLICATIONS FOR VINAMOLD HOT MELT COMPOUNDS
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
homes, bars, restaurants, hotels, banks, ships' saloons, civic buildings,
Souvenirs Replicas of antique items, figurines, doll heads, masks,
historical replicas. Educational/Museums/Arts and Crafts
dimensional topographical maps, biology models, sculpture replicas, fossil
unusual applications of vinamold are in life-size human figures, utilising
the flesh-like consistency of the material.
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