Finishing - Using Water-Based Paints

Painting a shoe rack

Water-based paints aren't as popular in India as they are in the West primarily because few people know about them and even fewer companies promote them.

In India, most paints used for coating wood and man-made materials are oil-based. The paint pigments, binders and other paint additives are dissolved or suspended in oil-based solvents which include turpentine and other chemicals. Some of these compounds have been found to be a health hazard and give off an unpleasant smell.

Water-based paints, on the other hand, are based on a different set of chemicals and use water as the primary solvent. They don't smell and have minimal levels of harmful VOCs (volatile organic compounds) which add to greenhouse gases in the atmosphere..

I have been using water-based paints for a while now and find they offer a host of advantages over standard oil-based paints.

Advantages:

Safety: In my opinion, this is the biggest advantage of these paints. Water-based paints do not contain highly volatile chemicals or solvents (like paint thinner which is highly poisonous) so you don't breathe in hazardous fumes. They dry without giving off toxic vapours.

No smell: Oil-based paints have a strong smell that can leave the room or workshop smelling for days. This can be quite unpleasant in the home. Water-based paints have virtually no odour.

Quick Drying: These paints dry incredibly quickly, within minutes and are completely dry in less than half an hour in our kind of climate - I believe they can be a problem in cold weather though. This means that a paint job which normally takes days could be accomplished in a day. That in itself is a game changer.

Hard and durable: Once dry, they are hard and durable. Hardness means that the surface coating is waterproof, can be cleaned easily with water and surf and can be buffed to a high gloss. I believe that this paint is also more durable than oil-based paints, has better adhesion to both metal and wood and resists fading.

Easy Cleaning: Cleaning brushes is a breeze as just plain tap water and soap are good enough.

I would be amiss if I did not mention some of the disadvantages of water-based paints.

Somewhat more difficult to apply: The paint is thicker and does not flow as well as oil-based paints. A good brush eliminates some of the problem but even then the high viscosity of water-based paints means it is less liable to even out. Brush marks are often visible after painting and need to be sanded down for a good even finish.

More expensive: Water-based paints are somewhat more expensive than regular oil-based paints and more difficult to find in hardware stores in India. Not too many companies market them.

I have made a short Youtube video (see at the end of this post) demonstrating the use of water-based paints in which I used primer and paint made by AkzoNobel and sold under the "Dulux" brand name.

A water-based primer such as this Dulux "Quick Drying Primer" is recommended for priming wood and metal surfaces before applying paint. Two coats is usually more than enough

This is the Dulux brand "Stay Bright" range of water-based paints. They are available in a wide variety of shades

The rack I painted was made from salvages boards from an old door

I made a simple shoe rack using old weathered boards salvaged from an old broken door. The idea was to find out how well water-based paints would do on these rather poor-quality surfaces.

I first sanded the rack with 80, 120 and finally 180 grit sand paper using a random orbital sander, then applied the Dulux "Quick Drying Primer" diluted with a wee bit of water to improve the flow. It was a little difficult to apply and left very visible brush marks. Perhaps I should have diluted it a little more but was afraid it would turn too watery and require many more coats.

After one coat of primer

At any rate, I sanded the first primer coat with 240 grit sandpaper. The great part was that the primer dried literally within minutes and did not clog up the sandpaper. The entire paint process went really fast - though in my case, I had to hold it for a day as I had other work to do.

I followed the standard steps:
one coat primer, sanding with 240 grit paper, filling cracks;
second coat primer; sanding with 240 grit;
first coat paint, sanding with 320 grit paper;
second coat paint, sanding with 400 grit and then 600 and 800 grit paper;
buffing with polishing compound (usually 3M).

Finished Rack

The result was most pleasing as the paint dried very hard and was ready for buffing in half an hour after the last coat. On some surfaces, I had to apply a third coat of paint as the coverage was not adequate.

I concluded that in future I would stick to water-based paints as there was no need absolutely to return to the smelly oil-based paints. For a real high-end finish though I would prefer the polyurethane route with a spray set-up but that is a different ball game altogether.

Indranil Banerjie
27 February 2020