By Abhijit Phadke
In the earlier article we discussed the several types of plywood available in the market. This time around lets take a look at which plywood is best suited for making kitchen cabinets.
Kitchen is one place around the home, where furniture is likely to be exposed to water, and will keep on getting wet. So the plywood that we select for making the kitchen cabinets has to have the ability to withstand water.
Now let's look at the types of plywood available in the market. There are many types, but only out two of them are majorly used for making home furniture.
1. MR grade
MR grade is moisture resistant plywood. This is an interior grade plywood and is meant for interior use. Its also known as commercial plywood. While it does look that moisture resistant is exactly what we require for our kitchen cabinets, that is not the case. 'Moisture resistant' does not mean 'Waterproof'. It just means that this plywood can successfully withstand a bit of 'moisture' and 'humidity' without getting damaged.
2. BWR grade
BWR grade plywood (Boiling Water resistant) is an Exterior grade plywood. It is made from phenolic synthetic resins (plastic resins) and is waterproof, and is considered to be a good choice of plywood for making kitchen cabinets.
The Indian quality standards for both MR and BWR grade of plywood are specified in document IS:303. The quality of BWR grade plywood is tested by taking samples of the plywood and immersing it in boiling water for a period of two hours, and then taking it out and checking its strength and other characteristics.
Plywood manufacturers in India, who meet the quality norms set by BIS as per IS:303 are awarded with a certification, after which they can display the prestigious ISI mark on their plywood sheets.
Coming back to the main point, what our kitchen cabinets require is the good quality BWR grade plywood, so that they last a lifetime. In addition the plywood is usually laminated, meaning a decorative laminate (such as Sunmica, Formica or other brands) is glued over the surface of the plywood. The laminate surface in itself is water-proof and it further decreases the chances of water reaching inside to the plywood surface. While choosing laminates, the thumb rule is that the thicker it is, the better it will be.
There is also another grade of plywood, called Marine grade plywood. This is a much superior type of plywood (Indian standards IS:710), that is majorly used in Marine applications such as for making boats and for the interior woodwork of ships. Using this plywood for making kitchen cabinets can be a very costly affair, and usually looks like an overkill.
The plywood shopkeepers sometimes refer to BWR grade as Marine ply. Its best to ask them the ISI number. The ISI number is marked just above the ISI mark on each of the plywood sheets. Only if it's IS:710 is it Marine grade plywood. Else if its IS:303 it means its MR or BWR grade. If it's IS:303, look for additional markings that say 'BWR' or 'Boiling Water Resistant'.
Additionally its better to check that there is a CM/L number mentioned below the ISI mark. CM/L number is the unique licence number that identifies the plywood company that has made the sheet, and every ISI mark has to be accompanied by a CM/L number. If CM/L is missing, the mark could be a fake one.
For furniture other than kitchen cabinets, using Commercial MR grade plywood is generally considered to be good enough. And wherever lengthy pieces of board are required, blockboard is considered better than plywood because it has a lesser tendency to sag or bend compared to plywood.
To summarize, Exterior grade BWR plywood is good for making kitchen cabinets and any other kitchen woodwork. Secondly laminating the plywood surface provides additional protection against water.