Red oak is a popular species. Used in kitchen cabinets, flooring, doors, moulding, and millwork, just about everyone has heard of it. What is important to know about this species and how can it impact how you work with it? Let’s dive in.
Red Oak in the Forest
Red oak is a deciduous hardwood with broad leaves that drop in the fall and have seeds that are contained in ovaries (red oak produces acorns). All deciduous trees are hardwoods. Red oak primarily grows in the eastern half of the USA. Mature oak trees grow to 60-75’ tall and 24-36” in diameter at breast height.
The growth rate of red oak depends greatly on location and growing conditions. Typically, the northern states produce slow growth red oak trees and the southern states produce fast growth red oak trees. This growth rate directly impacts the appearance and the physical and mechanical properties of red oak. For these reasons, red oak is sold in two separate categories; northern and southern red oak.
But one might be asking, what causes the red oak to grow faster in the south? The answer is a longer growing season and available moisture in the soil. Red oak in the south tends to grow in lowlands and swaps. This abundant amount of moisture allows the tree to grow very fast in the spring. This fast amount of growth will be present in the annual growth rings of the tree. The fast growth means there is more moisture in the wood, giving the red oak a very grainy texture and reducing the strength properties of the wood (the more water in the wood, the less wood there is itself). Check out our blog on annual growth rings for more information on this topic.
Manufacturing of Red Oak Lumber
Red oak is manufactured just like any other hardwood species. Since the tree is dominated by the heartwood (and the heartwood is what’s desired in the lumber,) the red oak logs can sit in the yard for some time before the log starts to experience any kind of defect. Here at Kretz Lumber, logs are first graded and then cut into lumber in our sawmill. We saw red oak in 4/4, 5/4, and 6/4 thickness and in lengths ranging from 4’-12’. We also saw the low grade cants into railroad ties or saw the cants into low grade lumber for flooring or pallet material. Once the lumber is sawn, the fresh lumber gets stickered to allow for air to flow between the layers of lumber. And this is where manufacturing red oak becomes a challenge.
Red oak has very large ray cells and ray cells are the weakest cell that exists in hardwood lumber. Because of their large ray cells, red oak has to be dried very slowly to avoid checking, splitting, or honeycomb. Red oak also has a very high green moisture content. It can range from 60-80%. Between these two things, red oak has to be dried very slowly for quite a long time before it’s ready to be used. Typically, it takes at least 30 days to dry quality red oak lumber from green to 6-8% moisture content in a conventional dry kiln. Some manufacturers will carefully air dry red oak to reduce kiln time.
After the lumber is dried, the stickers are removed. Our red oak is graded based on NHLA (National Hardwood Lumber Association) grading standards. The lumber can be sold as rough, or the lumber is machined to the customer’s desired thickness, width, and/or length.
At this point, the primary manufacturing process is complete and the lumber is sold to secondary wood manufactures. Secondary manufactures take the dried lumber and turn it into a finished product like flooring, cabinets, windows, doors, furniture, moulding, and millwork. Most of these manufactures have equipment like rip saws, chop saws, moulders, CNC routers, and finishing equipment.
The lumber would first be surfaced to a standard thickness, and then ripped to width, and chopped to length. Usually knots and other defects are removed when the lumber is ripped and chopped. The ripped and chopped lumber now takes on a new name like rips, blanks, or plugs. The blanks are fed through a moulder and the blank gets profiled into flooring, crown moulding, baseboard, or other similar products. Some windows and doors have curved parts. Typically, these parts are profiled with a CNC router. Any products that need to be assembled are assembled at this point. The last step of the manufacturing process is to stain and finish the product to the customer’s specifications, although some products like hardwood flooring are finished after installation.
Red Oak as a Product
Red oak is desired for its color, workability, and durability. It is a ring-porous hardwood and has a specific gravity of 0.63. Although it’s dense, it’s not too dense to cause problems while machining and gluing. Its density provides enough resistance to wear and tear to be used as durable flooring or a countertop. Its ring porous nature can make it more prone to chip out and tear out. It takes stains and finishes well, but it will absorb stains darker in the grainy parts of the wood.
Red Oak at Kretz Lumber
Our red oak is harvested from the slow growth forests of North America. Northern red oak provides consistency in color and has tight, open grain. It has white sapwood with reddish brown heartwood. Red oak is often found in flat sawn, rift sawn, and quarter sawn. Red oak is best used for veneer, flooring, furniture, millwork, caskets, wooden ware, handles, pallets, and crates.
We sell red oak in truckload quantities in a variety of different thicknesses and lengths. If you can’t find what you are looking for on our website, contact us via email or at 1-800-350-1438 and we’ll gladly help.