August 16, 2021

How to tell if Wood is Treated

You may have heard that many of the materials we use in our homes are treated with chemicals. You may also have heard that these chemicals have unintended side effects, including harm to your health or the health of others. Let us find out how you can tell if the wood has been treated.

How to tell if old wood is treated

Look for a stamp on the wood

Pressure-treated wood comes with a tag or stamp that informs you about the chemical used. The Green or brown color on the wood piece shows that the item has been through some treatment. 

There is a difference between treated and untreated wood, which is noticeable by smell. Treated wood smells oily due to the chemicals used, whereas untreated wood has a natural smell. A wood testing kit would be ideal if you cannot use the details above to differentiate between the two.

The tag also gives you the rating and the preservation company. There are two chemicals used to treat wood and Copper and Tebuconazole. Any chemical not mentioned does not prove that your wood is treated. The AWPA code on the wood shows that the wood is treated.

Wood Treatment Stamp Code Guide Table

CODEWhat The Wood is Treated For
UC1Interior Dry
UC2Interior Damp
UC3AExterior Above Ground, Coated with Rapid Water Runoff
UC3BExterior Above Ground, Uncoated or Poor Water Runoff
UC4AGround Contact, General Use
UC4BGround Contact, Heavy Duty
UC4CGround Contact, Extreme Duty
UC5AMarine Use, Northern Waters (Salt or Brackish Water)
UC5BMarine Use, Central Waters (Salt or Brackish Water)
UC5CMarine Use, Southern Waters (Salt or Brackish Water)
UCFAInterior Above Ground Fire Protection
UCFBExterior Above Ground Fire Protection

Look for signs of wood cracks 

As wood is an excellent treatment, it has to dry. That controls the moisture content the wood takes. That is referred to as Kiln Dried After Treatment. During the drying process, wood warps, twists, and cracks, and that is why you are not guaranteed a straight board. 

Treated wood shrinks across its width during the drying time. When it has been outdoors for extended periods, it develops cracks known as checks. These appear along the surface of your boards. These cracks are a sign of the drying process and are repairable.  

Look at the ends of the wood

Natural ends are not smooth and neat. They fray and resemble untreated wood. They are exposed and need to be dealing with chemicals. When you treat the wood, the ends are covered and look on the surface. 

Treating wood maintains a sealed end that you do not get on untreated wood. That is why treated timber is used on fence posts and walls. That shuns away insects and moisture. There is no need to trim off the ends. An End-treatment re-seals the cut ends. 

Look for 

Brown stains on the wood

Treated wood comes in an OD green or dark brown color. It has half-inch splits on the surface of the spot where the treatment was injected. The brown stain imitates Cedar. Cedar is a popular type of wood hence the arresting strategy. 

Treated wood contains solvents, and they have micronized copper azole (MCA). It is dark brown, although it washes off. With the introduction of copper-based wood treatments, the brown color does not resemble a toxic chemical. However, it preserves its color and retains it for a long. 

In some cases, the brown color fades away with time. That creates a natural-looking wood piece. The treated wood is green and a product of the chemical reactions between the wood’s preservative components. Copper also makes a green color in treated timber. 

Look for paint stripes.

Paint stripes do not indicate beauty only, but they represent treated wood. No point in making stripes when you do not intend to treat the wood. Paint stripes are an additional layer that preserves the wood from elements. 

As wood starts getting old, it turns grey. The wood gets old when eaten by termites and fungi. If there are not visible, cut in the middle to see if it is grey. When It is white, that means the wood is untreated. No treatment if it turns yellow or white. 

Look for a graying wood

Natural wood changes from its natural color as it turns silver-grey, indicating that the wood is untreated. The coloration process is a result of exposure to natural elements. Natural elements damage the wood, and in this case, the wood is unprotected. Manufacturers urge users to buy wood in time to keep it for a while observing it. 

Rushed work is quick but prone to mistakes and cannot be rectified effectively at that moment. There has been a new development whereby people willingly add the grey color, which confuses users since it is for treated wood. 

Look for a greenish tint.

A greenish tint is a sign that the wood has been treated. It has been pressure-treated with the CCA. That raised concerns with the Environmental Protection Agency in terms of safety issues. CCA is an arsenic-based formula that treats wood. 

CCA-treated wood is not used to make items that have contact with food, such as chopping boards. That resulted in Alkaline based wood for the CCA as the manufacturers tried to get rid of toxic substances. CCA stands for Chrome, Copper, and Arsenic, which are toxic substances. 

As manufacturers are trying to get rid of toxic chemicals, new methods have shortcomings. They penetrate the wood under pressure and are attached to the cellulose of the wood. That ensures safety and lasts long. 

Chemicals such as Borax do not seal the wood. The results are that wood is treated according to how it is used in woodwork. Older treated wood has a green tint.

Look at the retention level

Type of chemical used. The stamp on the wood gives you the wood’s retention level, which is a representation of preservatives retained in the wood. It is in pounds of preservative per cubic foot of wood. If the number is high, there are higher chances of rot resistance in the wood. 

Look for a fact sheet

A fact sheet is a summary of relevant information about treated wood. Type of chemical used. Do not go from one store to another to find the instruction sheet. Ask for the sheet from the manufacturer. The fact sheet contains the information you want to know about your product. The information on the fact sheet is the same information that is on the label. The facts and points remain brief and easy to understand. This is an advantage for users who have difficulty researching on the Internet. It is affordable and will be passed on to the next user.

David D. Hughes
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