Polydur is a unique tooling system that provides lightweight, accurate laminates in a very short working
time. Polydur has no health and safety aspects, is non toxic, has no smell and all its components are water
Polydur was originally developed by Denaco Imports Ltd over ten years ago and is now used
worldwide by a large number of industries and include tooling, automotive, aerospace, composites, art,
theatre and film sets and many other diverse applications.
The system consists of an aqueous emulsion of acrylic resin (EM25) that is mixed with a specially
formulated gypsum (LG) combination at a convenient mixing ratio of 100/50. This specific combination
is the key to the accuracy and short demould time of the Polydur system and also the final physical
properties and the suitability for many tooling applications.
The working techniques and characteristics are very similar to normal epoxy or polyester resin laminating
applications and consist of a thixotrope mix for a surface coat (SGP/L) and a low viscosity mix for
laminating. The laminating mix wets out glass fabrics and chopped strand mat, and very good results
are obtained using 300gm Neomat. The average weight of a polydur laminate using 2 layers neomat
is approximately 7.5kg/m2. Two layers is suitable for most laminates and very large laminates can be
reinforced with suitable stiffening ribs rather than extra layers of laminate.
The Polydur surface is a plastic type surface from which resin laminates or castings can be taken. However,
the laminating system also bonds to conventional epoxy gel coats so epoxy faced Polydur laminates can
be quickly produced.
The resulting laminates are de-mouldable in approximately 3 hours and can be used within 2 hours of demoulding.
Moulds from Clay Models
Film & TV sets
Models should be prepared in the usual way as with any resin system. 818 mould release has been found to
be successful with most materials (except styling clay) and applied by soft cloth and polished after solvent
evaporation. A minimum of two applications is recommended.
818 can also be used to take Polydur™ laminates from Polydur™. The Polydur™ laminate requires no
sealing, but three applications of 818 are advised.
Styling clay requires special consideration and varies with different styling clay products; suppliers should be
able to make recommendations in respect of this. JBB Styling Release has proved suitable for most styling
clays but tests should be done with individual styling clay types to determine suitability. Kolb Claypeel has
also proved suitable for taking epoxy faced laminates from clay.
Gel Coats - Polydur™ Surface SGP/L
It is important that the powder (SGP) is added to the liquid (SGL) and is mixed mechanically. This will
produce a creamy thixotropic mix, which should be applied with a soft longhaired brush.
A 500gm mix covers approximately 0.4m.
It is only necessary to ‘paint’ a thin layer, as this is subsequently ‘wet out’ with the same material in the
Polydur™ laminate. It is suggested that it be applied more liberally in corners to aid subsequent laminating.
The main function of this surface (unlike conventional gel coats) is only to keep the glass layer from the
surface of the tool.
This thin layer will cure (dependent upon temperature) within 30 minutes and will be
observed to turn uniformly white. Laminating can be commenced at any time after this,
giving ample time to prepare for the laminating procedure Epoxy Surface S15/S15R & Coupling Coat J-K99 / JB 404H
Where required Polydur™ tooling can be produced with an epoxy surface and S15/S15R has been
especially formulated for this application. Conventional epoxy gel coat procedures should be used and
Polydur™ laminating should be commenced at the tack free stage. The condition of the S15/S15R surface is
critical to ensure bonding with the subsequent Polydur™ laminate. For larger surface areas a coupling coat
is recommended and JB-K99 / JB-404H has also been specially formulated for this application. Polydur™
laminating can be applied to a wet JB-K99 / JB-404H surface. Slight exotherm occurs with JB-K99 / JB-404H, which aids S15/S15R cure and is usually de-mouldable within 2-3 hours dependent upon temperature.
It is recommended that during the application of S15/S15R an ‘off the job’ area is gelled in order to determine
Prior to laminating, the Polydur™ gel coat SGP/L or JB-K99 / JB-404H/S15/S15R surface should be ‘wet
out’ with the laminating mix, Polydur™ LG/EM25, to ensure bonding of the gel coat to the laminate.
Polydur™ Emulsion EM25 and Polydur™ LG are mixed by first adding the powder to the liquid. It is
suggested that a typical total mix should be 1500gm (1000gm LG / 500gm / EM25), and for larger laminates
3000gm (2000gm LG / 1000gm / EM25). Mechanical mixing is recommended.
The result is a low viscosity mix, which will wet out fabrics, chopped strand mat or Neomat.
1500gm mix laminates 0.5m² using 300gm Neomat.
A typical laminate of two layers of 300gm Neomat should weigh approximately 8.0kg / m² maximum. Weights
higher than this denote excess resin to glass ratio. 300gm Neomat is recommended for most applications
and large areas can be covered quite quickly. It can be observed that Neomat has a looped side. When
using two layers, it is suggested that the layers should be loop side to loop side. If three layers are used, the
third layer should be loop side down in order to have a smooth back surface. Care should be taken as with
any resin system not to ‘over wet’ the glass. Any excess should be rolled out, using a lamb’s wool type roller
which can be washed out in water after use. Neomat should be ‘wet out’ off the job as Polydur™ adheres to itself at any time, there is not the usual constraint in timing when laminating the first layer. A uniform laminate thickness is important. Overlapping of laminates should be avoided because thick and thin sections may lead to distortion of the laminate, as with other resin systems. Whilst little or no exothermic occurs with the system using two layers, thick sections may cause local exotherm. Two layers of 300gm Neomat are considered suitable for most laminate requirements.
On laminates where added rigidity is required, this can be achieved by local stiffening ribs. These can be
produced by laminating one strip of Neomat over pre-cut foam strips, to form a box section, again avoiding
excess resin. Particular attention must be paid to flanges because these aid subsequent de-moulding and
add rigidity and stability to the laminate. Honeycomb foam sheet is ideal for this application.
The Polydur™ laminating system requires 20°C for optimum results. At this temperature, the laminate will be
observed to cure within 2 to 3 hours by turning uniformly white and can be de-moulded at this stage. Demoulding is best achieved by using air pressure through holes or valves in the laminate to relieve the vacuum produced. To avoid damage to the model by drilling such holes, these are best provided during laminating.
Suitable size pegs or valves can be placed on the model and laminated around, leaving valves in situ or pegs
that can be removed. On de-moulding, it will be observed that the gel coat is no longer white. This requires a
further 2 hours to cure, at which time the laminate can be considered cured and ready for use.