G’day Guys and Girls,
I wish to touch on a subject, which I have been hearing about for 50 years (or so) Shitty Grout causing discoloration in finished grout lines. Over the years I have dealt with the majority of adhesive manufactures in Australia. Some I refuse to deal with, due to their lack of Quality, Commitment and service. Every few days my Staff and I receive a complaint from a client about patchy grout. The tiler becomes disheartened at the response from the company rep and refuses to buy their range of products ever again (Adhesive included). I have heard complaints about every manufacturer in Australia. COME ON NOW they can’t be all shit! No I’m not going against my own kind, I feel us tradies are victims of other forces at play, only a small percentage of the problem may be due to bad practice.
When you whackemon (new word) the floor, the good book says, part of the process is to clean the excess adhesive out of the grout lines, IF the tiles are properly bedded. Part of the laying process is to remove this excess adhesive, preferably whilst it is still soft. Shit hey, saw my legs off and call me shorty! The Old German I did my trade with, made sure that the neats on top of the bed came up the sides of the stone or tiles. However, it is not unusual for this not to happen, and then the next day, the grout is placed into the gaps and finished. Except on Sandstone/Freestone where we would grout then grind the entire surface flat. Another effect which occurs, is that because the adhesives are supposed to be applied with a notch trowel and the notch lines are rarely completely squashed down to make a continuous layer, this causes a line of glue next to a void under the tile. Larger notch trowels increase this situation. As the grout dries at varying thicknesses in the grout lines, the chemical reactions for cement occur differently, in part because the way the water stays in the grout (Thick & Thin) to react the cement, but also due to the differing properties of the adhesive (Thick & Thin) Where the grout is thinner it dries lighter, and where thicker dries darker. This pattern is then reflected in the grout and you end up with a “Patchy Look” in the grout lines. Easy to see with darker grouts.
Some dickhead in manufacture spilled the glaze over the tile edge. This can result in variations in colour due to differences in moisture absorption by the tile. This can be limited by wetting the grout lines with a fine water spray prior to grouting. P.S. This process slows down the time it takes to get to the watering hole with your mates! Laying and moisture issues. The grout application can have a bearing on the final colour due to both practice and site conditions. The grout is designed to be mixed with a certain ratio of water to form a soft paste of butter consistency that holds its shape. Where the installer has added too much water, this can alter the colour due to both alterations in the cement properties and also separation of the colouring oxides from the mix (that’s the scum look on the top in the bucket). And the excess water takes longer to dissipate from the grout leading to apparent darkness, and also blotchy in appearance. There is no simple remedy to this problem other than re-installation. If the grouts are badly mixed, then the colours can be variable because the colourants are not properly dispersed through the grout, this in my mind only applies to the old days when we mixed our own grouts (1 vegemite jar + 2 cups + 1 pint, f---- this I’m off to the pub). This day and age of company mixed grout is almost flawless. Ensure grouts are thoroughly mixed before application, and mixing should be sufficient to ensure water is absorbed. The grout powder is added to water and mixed to achieve a consistent paste, let stand for 3 minutes (what another cige!), restirred and then applied. Always use a clean bucket, and drinkable water.
Bloody Efflorescence (which means "to flower out" in French) is the loss of water (or a solvent) of crystallization from a hydrated or solvated salt to the atmosphere on exposure to air. This is a physical condition that occurs where water soluble salts rise to the surface and then when the water evaporates the salts deposit out as a powdery or crystalline crust. There are two types of efflorescence:
Grout efflorescence is typically whitish in colour and results from soluble calcium salts being deposited. (Talk to Ben this is his baby). It can be blotchy or produce an overall light colouration. Primary efflorescence occurs immediately and secondary occurs at a later date. Dark coloured grouts are more likely to show efflorescence due to colour contrast and all cement based materials can show efflorescence. Efflorescence occurs due to several conditions and is made worse by cool temperatures and overall dampness, therefore winter and coastal or very humid environments are more likely to show efflorescence. Where the tile installer has used excess water in both mixing the grout and also clean up, soluble salts can be leached from the grout cement (this also applies to the tile adhesive) and then deposits on the grout surface as drying occurs. Cool temperatures at the time of installation both prolong cement curing and also retards water evaporation. This can increase the likelihood of efflorescence. Where there is ground water, rising damp or damp slab, soluble salts can move with the ground water, or be leached from the slab, tile adhesive or grout and deposit on the grout, since this is the most porous area for evaporation to occur. Efflorescence may also appear on porous tile (good old quarry tiles) surfaces and brickwork. Ground water and rising damp are beyond the scope of this bulletin, but should be addressed as they lead to other more serious problems. Rain water running down tiled facades between the masonry walls and the tiled surface can generate significant efflorescence on the grout lines. Run off can also create efflorescence on the edges, but also within the field of decks. The tile grout has been applied too soon after the tile adhesive which has not fully dried. The moisture from the tile adhesive then leaches through the grout carrying soluble salts which deposit at the surface. The slab or screed was not dry, or insufficiently cured and then moisture travels up through the grout. I can’t stress how important this is, stick to the correct water mixing ratios during installation. Slabs typically take 28 days to cure, (useless information, the concrete bed for a sugar mill, mill train takes about 100 years) though drying is typically 25mm per month of slab thickness. Screeds take around 7 days to cure, and dry around 1mm per day. Check that rising damp is not present (the old rubber car mat trick). Try to work at temperatures above 10C and have adequate ventilation to promote water evaporation. Allow adequate curing times for the tile adhesive so SO important during the cold months. Once again talk to Ben he knows about efflorescence!
Cheers, Old mason’s ramblings, sorry.