MR grade means Moisture Resistant plywood.
BWR grade means Boiling Water Resistant plywood.
When we walk into a plywood shop for selecting plywood for our home furniture requirements, we need to be aware of the exact kind of plywood we require. But there are so many types of plywood available in the market these days, that it is necessary to be well informed to make a right choice.
Consider the above case of MR vs. BWR grade. People often think Moisture Resistant means waterproof. However this is not the case. Note that MR (Moisture resistant) is of a lesser quality and cost compared to BWR grade. While it true that MR plywood can resist a certain degree of moisture and humidity, it certainly cannot be called waterproof. On the other hand, BWR plywood is a waterproof plywood.
MR is an interior grade plywood useful for making indoor furniture, while BWR plywood is exterior grade.
The important points of difference between Commercial MR grade plywood and BWR plywood is summarized in the table below.
|BWR grade plywood||MR grade plywood|
|BWR = Boiling Water Resistant||MR = Moisture resistant|
|Has better strength and quality||Is of a slightly lesser quality|
|It's a waterproof plywood||It's not waterproof.|
|Phenol formaldehyde synthetic is used for glueing the plies together. This is a synthetic plastic resin.||Urea formaldehyde resin is used for bonding the plies to each other. UF resin is not considered to be very eco-friendly.|
|Exterior grade for outdoor use||Interior grade for indoor use|
|Preferred for making kitchen furniture that is likely to get wet||Preferred for making furniture that is not likely to get wet. e.g. Drawing room or bedroom furniture.|
PS: Some shopkeepers erroneously (or is it deliberately?) inform customers that Marine plywood is the same as BWR grade waterproof plywood. This is simply not the case. Marine plywood is a much better kind of plywood in which unextended (undiluted) phenolic resins are used for glueing the plies together, which makes it stronger. Marine ply is meant for extreme cases of exterior use, such as for making boats and ships or other river equipment, where the plywood is sure to become and remain wet for a prolonged duration.