AMPRO™ colloidal silica is an agent that is used to control the thixotropic or "sag" characteristics of a resin system. By adding colloidal silica powder in varying amounts to a resin mix containing the other types of fillers mentioned, the processing and curing characteristics can be controlled.
Relatively small quantities added to a resin mix containing glass bubbles or microballoons will give non-sag properties and impart easier handling. Colloidal silica is also used with microfibres to produce a mix suitable for use as a high strength, non-sagging structural adhesive, particularly for non-absorbent materials such as grp. The inclusion of colloidal silica has the effect of increasing the hardness of the resulting mix which will create more difficulty when sanding. For this reason colloidal silica is usually added in the minimum quantities to any mix for which sanding is anticipated. In some applications this feature can be used to an advantage, for example to create a hard wearing edge or surface.
AMPRO™ Silica is naturally water-resistant / hydrophobic making it more suited for marine applications. Lower loading levels are required compared to traditional silica, up to 2% reduction by weight...
For dosages and proportions see the technical datasheet in the attached files
Note: colloidal silica must always be added last.
Gurit have a range of powdered fillers designed to modify the properties of AMPRO™ multipurpose systems to create resin blends for use as fillers and adhesives. Fillers form three distinct categories: glass and phenolic microspheres, microfibers and thickeners (colloidal silica):
Hollow spheres
Increase the volume and reduce the density of any resin system and are used to make adhesive mixes and filling & fairing mixes.
¬ Microballoons: Brown microsphere filler powder used to make glues or paste fillers
¬ Glass Bubbles: White microsphere filler powder used to make glues or paste fillers
Short Fibres
For adding strength to a resin and hardener mix used as a structural adhesive, short reinforcing fibres are often added which act in a similar strengthening way to the long reinforcing fibres used in composite construction.
¬ Microfibres: Cellulose fibres used to make adhesive mixes
Flow Modifiers
The most common material for modifying the flow properties of a resin mix is colloidal silica. This is a very fine powder which is added in conjunction with other fillers to ‘thicken’ mixes and reduce their flow on vertical surfaces (increase thixotropy).
¬ Colloidal Silica: Fine, anti-sag, filler powder. Use in combination with other filler powders