Laminating Cloths
Chopped Strand Mat (CSM) Grade 1:
The most common form of reinforcement used with polyester resin for hand lay up. Strands of glass fibre are held together by an emulsion binder to form a mat. Supplied on a roll usually 92 cm wide in grades of various thickness expressed in weight per metre. Three most used are 300gm, 450gm and 600gm per mē. Polyester resin dissolves the binder allowing the fibres to follow the mould contours. A usual GRP structure would contain 2.5 kg resin to 1kg CSM. 1kg of 300g = 3.33mē. 1kg of 450g = 2.22mē. 1kg of 600g = 1.67mē.
Surface Tissue:
A thin glass fibre mat in a form similar to tissue paper. Supplied on a roll 1m wide and only 25-30 grams per mē. During moulding it is applied to the dried gel coat to cover up the coarse glass pattern produced by CSM. When sheathing It can be applied onto the CSM while the resin is still wet, again to cover the glass pattern and form a smooth surface for the flowcoat to be applied. Uses 750g of resin per mē.
Plain Weave :
Fabric 107cm wide Cloth is made from "Yarn" (twisted glass filaments) generally to produce a lightweight laminate with uniform thickness. Fabrics will flex more than CSM before breaking but are not as rigid. The best strength comes from the thinnest cloth with the tightest weave which tends to make them difficult to wet out and so for fabrics above 275g per mē woven roving is used. Adhesion between 2 layers of fabric is poor and should be avoided. Bonding is improved with thicker cloth and fewer layers or combining with CSM
Plain Weave 163gm:
Fabric Cloth is made from "Yarn" (twisted glass filaments) generally to produce a lightweight laminate with uniform thickness. Fabrics will flex more than CSM before breaking but are not as rigid. The best strength comes from the thinnest cloth with the tightest weave which tends to make them difficult to wet out and so for fabrics above 275g per mē woven roving is used. Adhesion between 2 layers of fabric is poor and should be avoided. Bonding is improved with thicker cloth and fewer layers or combining with CSM.
Woven Roving Fabric:
Supplied on roll usually 1m wide in grades of various thickness from 300g - 1000g per mē. It is not twisted is easier to wet out and drapes fairly well. As it cost less than fabric it is often used for boat building in conjunction with CSM as a simple means of adding bulk to increase stiffness. Fabric laminates use approx. 1kg resin to 1kg fabric
Carbon Fibre Fabric:
The best but costly reinforcement available for strong light weight structures with good fatigue and vibration resistance, low friction and good resistance to wear. Usually available in 1m wide rolls or tape form.
Aramid (Twaron/Kevlar) Fabric:
A high performance nylon type reinforcement giving a superior strength to weight ratio than glass fibre. It will provide up to 40% reduction in weight than glass fibre but is considerably more costly. Kevlar being difficult to cut requires a very sharp knife or specialist shears. Kevlar does not become translucent like glass. Polyester resins can be used but for maximum performance epoxy resin gives the best results. Usually available in 1m wide rolls or tape form.
Aramid Tape:
A high performance nylon type reinforcement giving a superior strength to weight ratio than glass fibre. It will provide up to 40% reduction in weight than glass fibre but is considerably more costly. Kevlar being difficult to cut requires a very sharp knife or specialist shears. Kevlar does not become translucent like glass. Polyester resins can be used but for maximum performance epoxy resin gives the best results.
Glassfibre Tape:
This is simple woven cloth in tape form supplied in roll widths of 25mm to 150mm weighing 175g mē. Open weave is the most common and easiest to saturate with resin but close weave holds its shape better. Used as a convenient to handle repair bandage.
Coremat:
A basic thickening material for rapid stiffening of GRP laminates. Although quick to apply it lacks the tensile strength of CSM. Should always be sandwiched between CSM. Each square metre x 1mm thickness will absorb approx. 600g of resin. Supplied in rolls 1 metre wide.