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The use of Mould Polishes and Cutting Pastes for Preparing and Polishing Glassgibre Moulds and Plugs

The production of a high surface finish to reinforced plastic products begins when the plug or pattern is made.
The preparation of the plug using mould finishing material will ensure a fine surface, and therefore a good mould, and a first class finished product. Starting with the plug, whatever material it is made of, it should be finally coated with polyester sealer, or other suitable finishing material. When this is hard the surface is progressively rubbed down with wet silicon carbide papers, filling and re-coating where necessary to remove all surface blemishes, finally finishing with a 1200 grit paper. On large areas an orbital sander will speed up this job.
When a satisfactory finish has been obtained, the plug is polished with Farecla Profile 200 and then followed by Farecla Profile 400, which must be completely polished off.
Finally the plug is polished with a mould release wax, and whichever wax is used at least 3-4 coats must be applied, avoid excess application, apply in a thin even film, leave for 30 minutes and then polish, repeat this for 3 - 4 applications or alternatively follow instructions on can. A plug finished in this way should produce a perfect mould, provided the mould is left on the plug for several days to achieve a full cure. To refinish a g.r.p. mould the suggestions for preparing a plug should be followed.
When starting to use a new mould, again 3-4 coats of wax are necessary, applied in the manner detailed above, before the first lay up. Before the second moulding is taken two waxings should be made, for the third moulding one waxing is given, from this point a number of mouldings, can be made without rewaxing.
For moulds which are intended to have a long production life, particularly involving volume production of mouldings with finely detailed surfaces, the use of a semi-permanent release film such as KANTSTIK CURE FAST is highly recommended instead of wax.

The following instructions apply to all our mould preparation materials.

Stage 1
The surface must be rubbed down with progressively finer grades of wet and dry paper, ending with at least 800 grit and preferably 1200 grit paper.

Stage 2
Burnish the mould surface using Farecla profile 200 Compound. Apply sufficient compound to form a thin smear over a small area and then burnish using either a clean cloth by hand or a foam mop in a slow speed polisher until the compound has disappeared. Wash off any traces of powder with clean water before proceeding to Stage 3.

Stage 3
M0164 Machine Cleaner Heavy Duty Machine Cleaner or Burnishing Liquid is applied to the mould using an electric or air buffer at between 700 and 1500 rpm. A lambswool or foam mop is suitable for this.
This process should be continued until the surface is free from scratches and shows a high gloss.

Stage 4
Apply Mirrorglaze 3 (M0364 Machine Glaze) or Farecla Profile 600 Professional machine Glaze in strips approximately 12" apart. Spread the product evenly over the mould     surface (or apply to pad of orbital buffer) and continue buffing until the material breaks down.

Stage 5
M0811 Release Wax or M87H High Temp Release Wax or Honeywax, this should be applied by hand using a soft cloth. It is not possible to use a power polisher. The wax should be applied in the manner one would use to polish a car. Rub the polish over an area approximately two feet square, then polish the film surface with a new cloth. After applying wax to the entire surface polish again, sighting across the surface to check that no smears are left.
This process should be repeated at six hour intervals to give a total of three complete waxings.
Hard work is required, but the results will pay dividends.

When polishing, care must be taken to remove all wax. If it is possible, a mould after waxing should be left overnight to avoid a blooming of the surface, before applying the gelcoat.
The above instructions are given as a general guide, but experience will indicate when it is necessary to rewax.
If there is any doubt whether a moulding will release easily owing to an imperfect surface or other reason, one of the Downland release agents should be used.