Question Centre

Well, you have opened a big subject that skirts the grading rules and gets into industry practice and flooring guidelines. Firstly, the NHLA grading rules do not address hardness. As discussed in previous articles, they are a measuring tool to determine the percentage of clear, defect-free wood on the face of the board. You have told me that you are using No. 1 and No. 2A Common grades, which are the sensible choice for your flooring. I have spoken with several walnut suppliers and no one is interested in sorting for density. This would be an almost impossible task from a mill's standpoint and, honestly speaking, a waste of time. So, let's talk about hardwood flooring and our practice in North America.

The National Wood Flooring Association (NWFA) and the National Oak Flooring Manufacturers Association (NOFMA) are the two primary groups that have set guidelines for solid wood flooring. Both use the JANKA Hardness scale as a means of comparing densities or hardness for a wide variety of woods from all over the world. A tropical species such as jatoba (Brazilian cherry) is in the 3000 hardness range, compared to hard maple and oak, that are in the 1300 range. American walnut is around 1000, which is on the lower end of the scale. This does not imply that you cannot use walnut for flooring, as it is entirely suitable for residential use. In fact, I even have it in my family room.

All hardwood flooring needs to be cared for properly. The biggest problem is caused by ladies' high heels and the pressure exerted will dent even the hardest of woods. Removing your shoes when entering the home is a great idea and is the custom in many parts of the world.

To answer your customer's concern, it is my experience that when hardwood flooring manufacturers guarantee their floors, this covers machining defects. Once the floor is successfully installed, the guarantee/warranty covers the finish, not the wood. There are many very high end manufacturers selling American walnut flooring without density being an issue. As I always told my flooring customers, you are walking on the finish, not the wood. I encourage you to look up the NWFA and NOFMA websites and also look up the JANKA scale. I am sure you will benefit from the information available.

This question needs to be included in every article I write pertaining to the NHLA grading rules. The No. 2A Common grade is required to have a minimum of 50% clear, defect-free wood on the poor face of the board. Splits, knots, and bad ends are unlimited on the other 50% of the board. Obviously this is a worst-case scenario. When a grader is sorting through the full output of the logs being processed, there is always a range of quality within each grade. For example, No. 2A Common needs a minimum of 50% clear and will include all boards up to but not including the next best grade, in this case No. 1 Common, which must be 66⅔% clear.

I always stress when teaching the rules that they are based on the percentage of good wood, not the bad. If you take a 10 foot board that has a big split 4 foot long, which makes that end unusable, and it is shipped as is, the grade will be No. 2A Common because 60% of the board is defect-free. If you think about it, if the shipper cuts this 4 foot off, the board then becomes 100% clear and priced as Selects and Better. The pricing for each grade depends on the grade, which depends on the percentage of clear wood on the board. Another point worth mentioning, a clear cutting from No. 2A Common is just as high a quality as the same area as on an FAS graded board. There just isn't as much and the price reflects this.

My first answer to this is to contact NHLA and come to America, where they conduct both the intensive long course and short courses, which last only a few days. Since this article is spread out all over the world, my next response is to contact your nearest AHEC office (www.ahec.org) and see when and where we will be conducting grading seminars. You can even request for us to come to your area if there is an association or big enough group interested. AHEC's goal is to get as much information about American hardwoods into your hands and heads, making it easier for you to make decisions about the source for all your hardwood needs.

I wrote a complete rundown of the sorting process for hard maple last year. Anyone interested in a copy can contact me. Having said that, the grading rules for hard maple address sapwood (white) sorts and heartwood sorts. After speaking with you, you wanted the white colour. The boards you surfaced ranged from very white to a slight pinkish colour. The grading rules do not address the degree of whiteness, only that they be sapwood and stain-free. There are certain times of the year when it is best to harvest hard maple, namely in the winter, which tends to produce a more consistent colour within a region. The slight variation can be attributed to the fact that hardwood is a naturally occurring product with natural characteristics.

Yes. There are three main steps, which I will outline as follows:

1. The Forest

American hardwood forests comprise a wide area, right from the northern states to the East and then into the far South. They are made up of broadleaf or deciduous trees, which shed their leaves each year, as opposed to softwoods or conifers, such as pine. Think of building   the structure of a house out of softwoods, such as 2x4 and then furnishing the interior with hardwoods, such as oak, cherry, maple and walnut.

US hardwood forests are approximately 70% privately owned in a wide variety of acreages and for numerous end uses. One such use is for commercial hardwood lumber production, where the landowner works closely with a sawmill to manage the trees and selectively harvest the mature ones, thus promoting the growth of the younger trees, until they, in turn, are harvested and the cycle repeats itself. The process of selective harvesting can also promote the species mix in the woodlot and increase the value of the timber stand for generations to come. Once the trees have been cut, they are loaded on to a truck and taken to the sawmill for processing.

2. The Sawmill

Most hardwood sawmills today are second or third generation family businesses, which are scattered throughout the hardwood growing regions. Once the logs are at the mill, they are sorted by species and cut to manageable lengths for processing. Any potential veneer logs (very high grade and defect-free logs) are taken out and the rest are stacked up awaiting their turn through the mill.

Logs that are ready for the mill are first sent to a de-barking machine. The bark is then recycled to produce garden mulch and bedding. Today, most sawmills use a band saw for cutting the logs in to lumber of various thicknesses and widths, depending on species and future order files.  Every effort is made to minimize waste throughout the milling process, from edging and trimming, to collecting and chipping any by-product that is produced from converting a round log in to square boards. Even the sawdust is collected and sold as bedding or fuel.

3. Grading & Drying

The lumber that's comes out of the mill is sorted in to various stacks depending on grade and thickness. Some will be sold as green or fresh sawn and the remainder will be stacked on to thin drying sticks, or stickers and prepared for the dry kiln. All hardwood destined for use in interior applications, such as furniture, flooring and mouldings etc. must be kiln dried. This is a highly skilled procedure, which can take anywhere from several days to over a year, depending on the species and thickness. In the United States, lumber is dried to a moisture content of around 6 to 9%, which is about equal to the moisture or humidity level inside most American homes. This drying process helps the wood to maintain its shape when manufactured in to a product.

Once dried, the lumber is graded for a second time to remove any downgrade material and to get an accurate measurement for sale. Most sales are made by truckload in the domestic market or stacked in to a 40 foot sea container for export. Depending on the species, a typical container will hold approximately 12,000 board feet or 28.3 cubic metres.