Ready-mixed versus powdered – the big debate

on 28 April, 2014

It’s no secret that knowing when to opt for a powdered adhesive over a ready-mixed is confusing – and, if the customer is questioning the product, the pressure is placed on the merchant to rise to the challenge and share their product knowledge. With this simple guide, I’m hoping merchants across the UK can feel a little more confident when it comes to advising on this age-old predicament.

The truth lies behind how the product dries. Ready-mixed is generally easier to use, but it has limitations attached to it. Here at Dunlop, we would never recommend using a ready-mixed product when using porcelain, large-format tiles and tiling floors, or wet areas. The drying chemistry behind a ready-mixed product doesn’t function well within these environments, as it requires a greater amount of water evaporation.

If you think about the product itself, it’s already wet, meaning the moisture levels in the adhesive are significantly higher than in a powdered product – resulting in longer drying times and a greater need to have access to air for moisture evaporation.

Take porcelain tiles for example: they have a non-porous surface, which reduces access to air. If they were attached to a surface using a ready-mixed adhesive, the middle of the tile would remain wet and fail to attach. This is called picture framing. The result can be disastrous, leading to unnecessary expense and time wasted, as the tiles will initially attach but are then at risk of coming loose or cracking when the adhesive fails to fully dry.

The same premise is also applicable to large-format tiles. Again, the larger surface area reduces access to air for moisture evaporation, and as any builder and merchant will know, these tiles are heavy. The result of a large-format tile failing to stick isn’t just costly and time consuming; it’s potentially dangerous – especially if the tile is fixed above shoulder height.

The same rules apply to the environment in which a tile is being used. If it’s a wet environment, there is an inevitable reduction in moisture evaporation, meaning the tiles will never fully dry and fix. When applying tiles to a floor, professional builders will need to consider that impact and movement is greater than on a wall. If a tile has been fixed using a ready-mixed adhesive, the likelihood of cracking is increased, as the surface beneath may still be wet – weakening the tile and increasing the chances of slipping or cracking.

Although ready-mixed is generally cheaper and easier to use, it is worth investing a few extra pounds into a powdered adhesive for such jobs. Powdered adhesives use a different drying chemistry. This provides added flexibility when it comes to the hold and drying consistency, helping the product to dry throughout, rather than in just the exposed areas.

Powdered adhesives are ideal for large-format and porcelain tiles and help to adhere a tile to floors and wet environments. The added strength, flexibility and drying consistency are absolutely essential to ensure a quality and long-lasting hold.

In short, merchants advising professional builders should always question the environment being tiled and the tile type being used before advising on a ready-mixed over powdered adhesives. This will save professional builders time, money and lots of hassle, leaving customers satisfied with a quality result from start to finish and tradesmen with peace of mind that the job has been delivered to the highest of standards.

Debi Boulton is brand manager of Dunlop.

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