Part of what makes wood so beautiful is its unique grain and the character that comes from it being a natural, living material. Back home We appreciate that. But because it has spent decades growing in a forest, real wood, and the furniture made from it, will never be perfect. For example, solid wood furniture will have some colour variations and marks, and it will expand or contract slightly with changes in the environment. But that doesn't mean every imperfection is acceptable. Sometimes there are flaws that are simply not right. So, what is considered normal and what is considered a defect when you decide to own natural wood furniture?
VISUAL CHARACTERISTICS OF SOLID WOOD FURNITURE
Colour variations – boards of the same type will look slightly different, both from wood to wood and within the same tree. A bit of science to explain why:

The outer part of the trunk is called sapwood and consists of active cells that transport water through the tree. This sapwood tends to be lighter in colour than the inner part of the trunk.
Colour changes – Once you bring your wooden furniture home, it will change colour as it's exposed to light. Cherry will darken, walnut will lighten, and maple will take on a honey hue. If you purchase naturally coloured (not stained) wood furniture, you can expect them to look different after about six months.
Variation of grain size – it is produced from the growth rings of the tree, which leads to the swirling lines you see running through the surface of wooden furniture. Within any given species, the grain on each plank will look different.
Knots The place where a branch enters the trunk can cause circular patterns called knots. Some species, like pine, have many knots – this is actually a characteristic of the tree. Larger knots are removed from boards before they are made into furniture, but smaller knots (sometimes called pin knots) are part of the tree's character.
Mineral stripes These are darker lines that follow the wood grain. They are caused by minerals that the tree draws from the soil as it grows.
DIMENSIONAL CHARACTERISTICS OF SOLID WOOD FURNITURE
The wood remains dynamic even after it has been cut and constantly adapts to its environment. Changes in environmental moisture will cause the wood to expand (this happens when there is more moisture in the air) or contract (caused by less moisture in the air). This movement can cause small but noticeable structural changes.

Normal
Sagging It's perfectly normal to see it in the middle of the table. This is due to the edges expanding more than the centre and is not a fault.
Void – If you have an extension table with a break in the middle, you may notice a gap in the centre of the opening that separates the two sides. This is not a defect.
Distortion – When one surface absorbs more moisture than another, the wood will drastically warp or bend. If you notice a curve running the full length of the table, this is warping. This can be avoided if there is no more than 15 centimetres of wooden surface without support (additional pieces of wood should be attached to the underside of furniture panels).
Differences in wing size – If the table leaves are stored elsewhere in your house, you may notice a slight difference in width when you attach them to the table. If you have drop leaves (extension leaves that are added to the ends of a table), these might be slightly smaller than the table's edge.
Cracks – If a piece of wood goes into a home in a dramatically drier environment, it can crack. This should never happen if the owner of the furniture takes proper care of it. You should be able to accept small cracks. This is not a defect.

Defect
Construction gaps – Cabinets are made by constructing a large box, then adding drawers and doors. You may notice some gaps where the different wooden surfaces are joined together, or around the front of the doors and drawers.
Adhesive marks Large wooden panels are made by gluing wooden boards together; this is usually a very strong construction and should not show any cracks.
The natural grain of wood brings a beautiful, organic element to your home. Variations in the appearance of wood should be embraced for their unique look, rather than be noted as a defect. While major structural changes in timber should be a concern, some minor fluctuations are normal and nothing to worry about.