Internal and External Mould Release Agents

External mould release agents, on the other hand, are sprayed into the open mould. They are often based on paraffins, soaps and oils, e.g., silicone oil. Because of the manner of treatment, these mould release agents may be found not only on the surface but also in layers near the surface. Proprietary non-transfer mould release agents such as Frekote are recommended to ensure optimum bonding surfaces. 

If mould release agents are present, cyanoacrylates can sometimes be used successfully in conjunction with a primer to give excellent bond strengths. 

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