POLYVINYL ACETATE ADHESIVE

Preparation
To achieve results it is important that preparation is carried out thoroughly. Although SpECbond PVA has exceptional adhesive properties it will not perform efficiently on contaminated surfaces. Remove all flaking and cracking paint, unsound plaster, oil, grease and friable matter to provide a stable substrate. Highly absorbent surfaces such as Concrete, Foam and Slag blockwork may require pre-wetting before application of SpECbond PVA sealer. Please note that PVA should not be used as a bonding agent where wet conditions are continuous or in highly humid areas – see data of SpECbuild BA10.

For use as an adhesive
When bonding wood to wood apply a thin coat to one face only and press together firmly. On large surface areas, certainly with laminated plastic, clamping or weights may be required for up to 24 hours. Very porous surfaces will need to be primed with 1 part SpECbond PVA diluted with 3 parts water and allowed to dry before carrying out the adhesive operation. It is not recommended that unmodified SpECbond PVA be used for gap filling where gap filling in necessary perhaps in the bonding of plasterboard, polystyrene, acoustic board etc., a suitable filler should be used to modify SpECbond PVA. Mixing equal parts with water and adding fillers such as plaster, cement, fine sand or sawdust would accommodate the gap filling requirement – consult our Technical Services Department if a detailed specification is required.

For use as a plaster, cement/sand render & screed bonding agent
Normally, on most surfaces, no mechanical hacking or keying is required before application of gypsum plaster. Mix SpECbond PVA with an equal part of water, apply to prepared substrate and allow to become tacky before plastering in the normal manner. For heavier rendering using sand/cement systems, seal and prime as above but employ an intermediate bonding slurry prepared by mixing 1 part ordinary Portland Cement with 1 part SpECbond PVA to 3 parts water. Apply the slurry to the still tacky primer with a stiff brush to achieve a rough surface or stippled surface. Allow to harden, check adhesion to substrate and apply rendering. When rendering on glazed tiles or highly polished surfaces it is suggested that light pick hammering should be carried out before following the above recommendations.

For use as an admixture in cement/sand or granolithic screeds
This incorporation of SpECbond PVA allows for reduced thickness floor screeds to be laid without recourse to setting out bays. The ability to lay at reduced thickness enables the operator to redress unacceptable differences in levels but resolution of these levels should be confined to between 9 to 19mm thickness of screed.

Areas subjected to light traffic should be primed as recommended and screeded with a mix of 3 parts sharp sand, 1 part cement and gauged with 8 litres of SpECbond PVA per 50 kg of cement.

Where heavy traffic is envisaged use a mix of 1 part sand, 1 part cement and 2 parts granite (6 to 3mm) – gauge with SpECbond PVA at the rate of 10 to 15 litres per 50kg of cement and add a little water if necessary but this type of screed should be mixed semi-dry, never overwet. Lay the screed on a tacky bonding coat, tamp and trowel to a smooth finish. SpECbond PVA/sand/cement screeds can normally be opened to light foot traffic in 36 to 48 hours and granolithic 24 to 36 hours. Before opening to heavier traffic allow 3 to 7 days depending on the type and weight of traffic.

For use in repairs to concrete
Prepare damaged or worn concrete as recommended and attempt to cut-back perimeter edges of the area to minimise the necessity for feather-edging’. Prime with equal part SpECbond PVA and water and repair whilst primer is still tacky.

The repair mix should consist of 1-part cement and 2-part sand gauged with a mixture of 1 part SpECbond PVA to 3 parts clean water. Compact firmly but do not over-trowel.