What is Sapwood vs Heartwood

Sapwood and Heartwood are considered before a lumber cut when working with lumber. As Furniture Refinishers, however, you have probably never heard of either type of wood. I have only encountered one situation where I had Heartwood and Sapwood on a teak cabinet. At the time, it caused me some confusion. The solid teak cabinet top was a deep, rich brownish red, except for a corner that turned nearly blond. It threw me for a loop because I was unaware that a single tree could produce two dramatically different wood tones. Therefore, I needed to understand Heartwood vs Sapwood to identify wood types in furniture refinishing. 

Table of Contents

What is Sapwood?

Sapwood is the youngest growth ring in the tree trunk and is located between the bark and the Heartwood. The living part of the tree truck contains live cells and sap that transport water and nutrients up the trunk from the roots to the branches and leaves. Each year, as the tree ages and grows, it increases in diameter and produces new Sapwood on the outer layers. As more outer rings and new wood develop, the inner rings slowly die off and heartwood forms.  

What is Heartwood?

Heartwood is the inner core of wood in a tree and is surrounded by Sapwood. The inner core is no longer transporting water and sap for the tree. It is the oldest part of the tree and is no longer living. It contains dead cells that are no longer active in the tree nourishment. This process takes a long time and is part of the tree’s ageing. 

Over time, this inner wood will be deposited with tannins, gums, resins and natural oil. These natural chemicals give the Heartwood its unique look compared with the Sap wood. Slowly, these additions to the wood will produce significant colour changes. Most commonly producing darker tones. 

This section of the tree may be dead wood, but it still has an essential function as the centre of the truck and structural support of the tree.

Differences Between Sapwood and Heartwood

Colour: Heartwood is usually darker than the lighter Sapwood. This is due to the buildup of Heartwood’s tannins, resins, oils, and gums over time. While the Heart wood is usually darker, it is not always true.

Density: Heartwood is denser and more robust than the less durable Sapwood, which is softer. The Heartwood is the centre of the trunk, which supports the tree. Meanwhile, the Sapwood contains living cell walls and is porous for water transport. 

Durability: Heartwood is more rot-resistant and more durable than softer Sapwood. 

Moisture Content: Heartwood contains less moisture than Sapwood. 

The amount of Heartwood to Sapwood varies from tree species and depends heavily on the tree’s age. Young trees will naturally have more significant quantities of Sapwood, and an older tree will contain more Heartwood. 

sapwood and heartwood picture depicting the colour differences

Colour Variations in Wood

Wood colour can vary significantly between the Sapwood and Heartwood of the same tree. This is what I experienced on the top of the teak cabinet. The sliver of wood on the edge was so different in colour that I initially assumed it was a poorly made repair. After discussing it with a wood expert in the business for over 50 years, he looked at it and informed me it was solid Teak with part of the Sapwood. 

In more significant sections of wood, you may find colour variations, which could make you unsure of the wood you are trying to identify. Consider that it may be a piece of Heartwood and Sapwood, which could confuse your outcome. 

solid Teak Top with a section of sapwood in a lighter tone.
That sliver of blond Teak is the sapwood

Impact on Staining Wood

Due to the difference in porosity and tannins, Sapwood and Heartwood absorb stains differently. The softer Sapwood is more porous and will absorb stains faster and deeper than the denser Heartwood. Suppose you believe that your piece of furniture contains both Sapwood and Heartwood. In that case, you will need to take this into consideration. You may need to leave stains on the Heartwood longer and adjust the stain ratio to thinner. 

Importance for Furniture Refinishers

Understanding the differences between Sapwood and Heartwood is valuable knowledge for furniture refinishers. Take into account the teak top, which consists of Heartwood and Sapwood. Had I wished to stain the top (who would stain Teak?!?) I would have had to adjust the stain for the two wood sections. I may have needed to stain the Heartwood longer to colour-match and mask the different tones in the wood.

Furthermore, learning that a piece of wood from a single tree could consist of a range of colour differentiation has made it easier to determine wood species. 

Looking For More Resources?

One of the most helpful tools I have for wood identification is the Veneer Identification Kit from Sauers & Company.  This kit comes with a variety common woods used in furniture making, as well as a variety of exotic wood.  Being able to see and touch the wood helps to improve your abilities to identify wood types.  

Each veneer sheet is clearly labelled with the type of wood and the type of cut that was made. 

 

Various pieces of veneer as part of the wood identification kit from Sauers
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Hey, I'm Sarah, the owner of Bold Wallflowers.

I'm on a self-taught journey through furniture refinishing and restoration, loving every experiment in my workshop.

Join me as I share my discoveries and gained knowledge with our vibrant community of fellow refinishers!

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