Saturday, 29 April 2017

Cement Based Powder Tile Grouts Vs Epoxy Tile Grouts

Tile joint fillers also known as grout are traditionally white cement based powders that are used to fill gaps between tiles and other gaps in bathrooms and flooring. It is common practice even today to use white cement dyed with mineral based powder pigments (known commonly as oxide powders) to fill tile joints in bathrooms, flooring and terraces. While this fills the joints, it is not very long lasting. Being a cement based compound, it is not waterproof. It is absorbent and as a result carries moisture, leading to fungal/algal growth. This is what gives that ugly black/green stain to the tile joints. Also being a lime based product, it is not resistant to common cleaning agents such as acids and bathroom cleaners. This leads to erosion of the grout and ultimately water leakages through the joints.

To cover some shortcomings such as quick discolouration and uniform colour matching, many powder based cement grouts are available. These powder based cement grouts don't do much more that the above. They have no great resistance to cleaning agents and also are not waterproof. Some powder grouts do have additives to enable wide-tile-joint filling where normal grouts tend to crack. SBR based additives are also available to enhance the waterproofing capabilities of powder grouts, but they do nothing to enhance the resistance to cleaning agents.

Epoxy grouts cover all the above shortcomings. They work well as waterproof and chemical resistant tile joint fillers. They also work well on wide tile joints. They have a smooth glossy finish and never loose colour.

Epoxy grouts are supplied as 2 part or 3 part packs. They consist mainly of a resin and a hardner. 2 pack epoxies usually have a coloured resin and 3 part epoxies have clear resins and hardners and a third pigmented powder component used as an opaque filler. 2 part epoxies are easier to use in that they are easier to mix and apply. 3 part epoxies are cumbersome to mix and cause some amount of wastage.

Unlike powder grouts which have to be mixed with water to get a paste like consistency to apply. Epoxy grouts are ready to use once all its components are mixed. The mixed epoxy has a pot life of 25-45 minutes. It is prudent to be cautious while deciding on the quantity of material to be mixed. Mix only so much that can be used within its pot life. The immediate tack free time is about 10-15 minutes after application. The excess grout must be cleaned up before about 20 minutes from application. The only drawback for epoxy grouts is that it can leave behind a mess if not cleaned up properly in time. Epoxy grouts are usually applied using spacers between tiles so as to provide larger surface area for the grout to bond to the substrate. Spacers of 3mm minimum are recommended. Epoxy grout needs a dust and moisture free substrate.

Most bathroom leakages can be arrested using epoxy grouts. Epoxy grouts applied in a contrasting colour to the tiles form a beautiful grid pattern that is both modern and minimalist in design.

Epoxy grouts, as discussed above, out-perform on most criteria and are the future in tile laying.

For Commercially available Epoxy Grouts refer to "Bathroom leakage repairs - Waterproofing Tile Joints using Epoxy Grouts".

Wednesday, 12 April 2017

What is the Difference Between Duco NC Lacquer and PU?

Duco is a brand owned by Akzo Nobel (formerly ICI) and represents a Nitro Cellulose (NC) Based lacquer available in transparent and opaques. NC lacquers were widely used in the automobile industry to finish vehicle bodies to get a tough weather resistant, glossy film with performance far superior to the then prevalent enamels. But there were a few drawbacks to NC. NC Lacquers are highly viscous and take large amounts of thinner to thin to a sprayable consistency. Nitrocellulose on exposure to sunlight deteriorates, looses gloss and turns yellow. It is also notorious to apply on edges and often begin to peel off at the edges. The NC paints needed to be periodically buffed to remove the yellowed top layer. This leads to reduction of the paint film thickness. NC lacquers are also sensitive to ambient temperature and humidity during application. The temperature and humidity are known to adversely affect the gloss of the finish.

With the advent of Polyurethane coatings, NC began loosing popularity as the preferred choice for vehicle body painting. PU as polyurethane is popularly known, has far better technical specifications to NC. PU is colour fast in sunlight and does not deteriorate even on prolonged exposure. PU forms a tougher film than NC due to extensive cross-linking introduced in the polymer. PU does not chip or peel off like NC. No buffing is required to maintain colour and gloss. PU can also be applied in a wide range of atmospheric conditions as compared to NC. PU is also easier to tint and match than NC due to the clarity of its binder and lower viscosity. PU can also be tinted to metallic shades. PU is also available in matt finishes.

Both NC and PU are used to coat wood and metal. These materials are also in wide use in home decor. PU is now the leading coating in the automotive industry and is fast gaining popularity in the decorative segment as well.

With green standards fast becoming the norm, PU is also available in water based variants that can be used to coat wood. They have a comparable performance to Solvent based PUs and are much easier to apply. They don't require elaborate spray equipment and also do not pose a health hazard as they can be brushed on.

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