in at the deep end

Architect's memo 42: November 1984

Early summer. The time to shake the moths out of the cricket whites, make any necessary running repairs to the barbecue, and refill the swimming pool – or should it have another coat of paint first? There is nothing quite as effective as pool re-paint enquiries for sending paint technologists slinking off into dark corners, clutching their worry beads in one hand and their valium bottle in the other.

Swimming pools are almost totally unpredictable - their behaviour depending on such diverse factors as construction methods, construction materials, water tables, how wet the summer is, what previous coatings have been used, what water treatment chemicals have been used. Equally, the stories are legion of the startling variety of coating types that have supposedly been successful in swimming pools. We ourselves have evaluated low build porous acrylics, aggregate filled acrylics, acrylic mastics, solvent epoxies, waterbased epoxies, urethanes, acrylic urethanes; but a review of the history of these coatings, plus a review of the recoatability and long term maintenance of these various systems, brings us back to chlorinated rubber.

The features of chlorinated rubber which keep winning through are excellent water resistance, single pack convenience and excellent recoatability.

Ideally we would like to see the following steps followed when building and coating a swimming pool:

1. Damp proof membrane to be laid before the floor is poured and also to be applied to any of the exterior wall surfaces which may be underground.
   
2. Pools to be left a minimum of four weeks to dry before (re) coating.
   
3. All concrete pools, new or used, to be acid etched, rinsed and dried before coating.
   
4. Mask off all sealant-filled joints and leave unpainted.
   
5. Coat with three coats of chlorinated rubber, allowing a minimum of 12 hours between coats.
   
6. Allow the finished coating to cure one week before filling.

In the area of recoating our advice is that where it is established that chlorinated rubber has been used previously: thoroughly scrub the surface clean, allow to dry, and recoat with two coats of chlorinated rubber. Where the existing coating is not chlorinated rubber, or is unidentified, our advice is to remove all old coatings by lightly sandblasting and treat the pool as new, without using the acid-etching step. Should this procedure be considered too drastic or expensive, we suggest you consult the yellow pages for alternative advice.

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