Maintaining Your Wood Cutting Board and Knives

Wooden cutting boards and knives are my most used kitchen tools.  Obviously, as for myself, we use all-natural wood and not polypropylene or polyethylene (plastics) cutting boards.  I don’t buy organic food but I try to avoid products produced from natural gas, feedstocks derived from natural gas processing, and feedstocks derived from crude oil refining (i.e., plastics).

Wood or Plastic?

Wood because it’s the best choice for maintaining a knife edge and wood cutting boards and knives simply look nice.   Most chefs will tell you that they find most plastic boards quite ugly, especially over time as they stain and get roughed up. Eventually plastic boards need to be discarded, whereas I’ve had some of my wooden cutting boards for over 30 years.  Wood cutting boards and knives need about 5 minutes of love each month.  There are many options for maintaining your wooden kitchen items, but I use a mixture of mineral oil and beeswax.

Process

Wooden cutting boards need to be kept clean and the best maintenance is washing with hot soapy water after using.  Do not clean wooden kitchen items in your dishwasher.  This will dry them out and cause cracking.  Initially, the cracking may not be visible to the naked eye but rest assured it is there.  You should never soak your boards or knives in water.  You run the risk of cracking because the moisture content of the wood is increasing quickly while uner water and then decreasing quickly as it is removed.  To sterilize your wooden kitchen items, you can use a very diluted bleach solution or hydrogen peroxide to clean their boards after they’ve been used for cutting raw meat as a precaution against bacterial contamination.  

You should oil wood cutting boards and spoons to help maintain their surface and keep them from cracking. I try to do this monthly.   You may need to do it more or less often.  You have many choices to use for oil.  Whatever oil you use must be food grade and not prone to rancidity.  Mineral oil is an inexpensive and popular choice, and is readily available.  The boards must be clean and dry before oiling.  The oil should be rubbed on with a clean cloth or paper towel and allowed to soak in as long as possible.   A good practice is to apply the oil in the evening after cleaning up from dinner, and then gently wipe off any excess oil on the surface the next morning.   If the wood has an unpleasant odor, apply a small amount of beeswax or lemon oil to the oil.

You should oil wood cutting boards and spoons to help maintain their surface and keep them from cracking. I try to do this monthly.   You may need to do it more or less often.  You have many choices to use for oil.  Whatever oil you use must be food grade and not prone to rancidity.  Mineral oil is an inexpensive and popular choice, and is readily available.  The boards must be clean and dry before oiling.  The oil should be rubbed on with a clean cloth or paper towel and allowed to soak in as long as possible.   A good practice is to apply the oil in the evening after cleaning up from dinner, and then gently wipe off any excess oil on the surface the next morning.   If the wood has an unpleasant odor, apply a small amount of beeswax or lemon oil to the oil.

Theory

Wood is a hygroscopic material, which is just a fancy way of saying that it will gain and lose water depending on the ambient conditions.  Wood is also an anisotropic material, which again is a fancy way of saying its properties, in this case shrinkage and swelling, are different in the different directions (width, thickness, and length).    Changes in wood moisture content between 0-30 percent will result in either shrinkage or swelling.  Changes above 30 percent will not affect the dimensional properties of wood.   Wood will swell or crack as a result of rapid changes in moisture content.  Food grade oil will coat the surface.  The purpose of the oil is to penetrate the wood and saturate the wood fibers to stop any other liquids (water, blood, etc.) from soaking into the board. A well-oiled cutting board 

or knife will keep the same shape when the wood fibers are saturated, so it will not expand and shrink and therefore will not crack or warp.

Todd Shupe is the President of DrToddShupe.com and is a well recognized expert on wood-based housing and wood science.  Shupe worked as a  professor and lab director at LSU for 18 years and Quality Manager for Eco Environmental (Louisville, KY) for 2 years. He is active in several ministries including his Christian blog ToddShupe.com. Todd is the Secretary of the Baton Rouge District of United Methodist Men, Database Coordinator for Gulf South Men, and volunteer for the Walk to Emmaus, Grace Camp, Iron Sharpens Iron, Open Air Ministries, HOPE Ministries food pantry. Todd is currently preparing to be a Men’s Ministry Specialist through the General Commission of United Methodist Men.

Fractionation of Heavy Metals in Liquefied Chromated Copper Arsenate (CCA)-Treated Wood Sludge Using a Modified BCR-Sequential Extraction Procedure

DrToddShupe Image CCA Agric Fence post
The photo is courtesy of Mike Freeman

Summary of CCA Sequential Extraction

Chromated copper arsenate (CCA)-treated wood was liquefied with polyethylene glycol/glycerin and sulfuric acid. After liquefaction, most CCA metals (98% As, 92% Cr, and 83% Cu) were removed from liquefied CCA-treated wood by precipitation with calcium hydroxide. The original CCA-treated wood and liquefied CCA-treated wood sludge were fractionated by a modified Community Bureau of Reference (BCR) sequential extraction procedure. The purpose of the BCR-sequential extraction used in this study was to examine the availability of CCA metals in treated wood for reuse. Both As and Cr had a slightly higher concentration in the sludge sample than in original CCA-treated wood. The sequential extraction showed that As and Cr were principally existed in an oxidizable fraction (As, 67%; Cr, 88%) in original CCA-treated wood. Only 1% of both As and Cr were extracted by hot nitric acid with the last extraction step. The distribution of As and Cr changed markedly in liquefied CCA-treated wood sludge. The amount of As in the exchangeable/acid extractable fraction increased from 16% to 85% while the amount of Cr increased from 3% to 54%. Only about 3% of As was present in the oxidizable fraction. However, there was still about 34% of Cr in the same fraction. Based on these results from sequential extraction procedures, it can be concluded that the accessibilities of CCA metals increase markedly by the liquefaction–precipitation process.

CCA Removal Methods

For many years, chromated copper arsenate (CCA) was the most commonly used waterborne wood preservative in the world. Despite the decision of the US and Canadian wood preservation industry to voluntarily withdraw the use of CCA-treated wood from residential and consumer uses as of December 31, 2003 (US EPA, 2003), the use of CCA-treated wood for industrial purposes (e.g., utility poles and marine pilings) continues (Song et al., 2006; Block et al., 2007). In addition, with an expected average service life between 20–40 years, the amount of spent CCA-treated wood in the US and Canada will greatly expand from the current 3–4 million m 3/yr  to around 12 million m 3/yr in Canada and the USA within the next 15 years (Cooper, 2003).  Many efforts have been made to develop appropriate alternative technologies for disposal of spent CCA-treated wood other than traditional landfills and incineration, which have raised environmental and human health concerns. A method to remove Cr, Cu, and As from spent CCA-treated wood based on wood liquefaction has been developed by Lin and Hse (2005). They reported that CCA-treated wood can be liquefied under similar liquefaction conditions as non-treated wood and up to 99% of the heavy metals can be removed from CCA-treated wood by adding ferrous salts during the liquefaction stage. In addition, CCA-wood complexes are either released from the decomposed lignin and cellulose or remains as the complexes or chelates with decomposed lignin and cellulose during the liquefaction reaction, which should provide better accessibility for the extractants in the heavy metal removal step.

Although many CCA metal removal methods, such as chemical extraction (Kartal and Clausen, 2001a; Kakitani et al., 2006) and bioremediation (Clausen, 2004b), have been proposed, very few studies have focused on both removal and reuse of CCA metals. It has been generally considered that Cr(VI) is reduced to Cr(III) and which then precipitates with As(V) and Cu(II) in wood components during CCA fixation process. Therefore, it is essential that the recovered CCA metals should be in an appropriate oxidation state which can be reused as a treating solution.

Todd Shupe is the President of DrToddShupe.com and is a well recognized expert on wood-based housing and wood science.  Shupe worked as a  professor and lab director at LSU for 18 years and Quality Manager for Eco Environmental (Louisville, KY) for 2 years. He is active in several ministries including his Christian blog ToddShupe.com. Todd is the Secretary of the Baton Rouge District of United Methodist Men, Database Coordinator for Gulf South Men, and volunteer for the Walk to Emmaus, Grace Camp, Iron Sharpens Iron, Open Air Ministries, HOPE Ministries food pantry. Todd is currently preparing to be a Men’s Ministry Specialist through the General Commission of United Methodist Men.

Rapid Microwave-Assisted Acid Extraction of Metals from Chromated Copper Arsenate Treated Wood

Rapid Microwave used to treat wood
Photo by Karelj

Abstract – Chromated Copper Arsenate Treated Wood

The effects of acid concentration, reaction time, and temperature in a microwave reactor on recovery of CCA-treated wood were evaluated. Extraction of copper, chromium, and arsenic metals from chromated copper arsenate (CCA)-treated southern pine wood samples with three different acids (i.e., acetic acid, oxalic acid, and phosphoric acid) was investigated using in microwave reactor. Oxalic acid was effective in removing 100% of the chromium and arsenic at 160°C and 30 min., and acetic acid could remove 98% of the copper and arsenic at the same conditions. Oxalic acid greatly improved the extraction efficiency of arsenic and chromium when time was prolonged from 10min. to 30min. Acetic acid also showed improved ability to remove arsenic and copper when the reaction temperature was increased from 90°C to 160°C.

Introduction

Preservative-treated wood products are well known to significantly prolong service life, and thereby extend the forest resource and enhance its sustainability. Inevitably, large volumes of preservative-treated wood are decommissioned each year. It is estimated that about 3-4 to 12 million tons of spent preserved wood will be removed from service in the United States and Canada in the next 20 years (Kazi and Cooper, 2006). Disposal of the spent CCA-treated wood has become a major concern because of its residual toxic components, particularly arsenic and chromium. Conventional waste disposal options for spent preserved wood, such as burning and landfilling, are becoming more costly or even impractical because of increasingly strict regulatory requirements (Townsend et al., 2004). The burning of treated wood can be extremely dangerous and even more so when the wood has been treated with CCA. Studies have shown that burning of preservative–treated wood waste emits highly toxic smoke and fumes in the environment (Solo-Gabriele, 2002). In the case of landfills, studies have shown that CCA3 compounds can be gradually leached out (Townsend, 2005; Moghaddam, 2008). Moreover, there is concern regarding landfill capacity. Therefore, there is an urgent need for developing techniques for recycling CCA-treated out of service wood. Several chemical methods have been proposed to extract the metals from CCA-treated wood. Solvent extraction can dissolve the preservatives and partially remove them from the wood. The used of acid extraction to remove CCA components from wood has been extensively studied (Kartal and Clausen, 2001; Son et al., 2003; Clausen, 2003; Clausen, 2004; Gezer, 2006; Kakitani 2006; Kakitani 2007). One of the advantages for acid extraction is based on its potential ability of reversing the CCA fixation process, thereby converting CCA elements into their water-soluble form (Kartal and Clausen, 2001). However, among the disadvantages of this recycling method are the huge amount of chemical solvents used and the long duration of the process. The prevailing treatment times reported ranged from 16 h for sawdust (Clausen and Smith, 1998) to 24 h for chips (Kartal and Clausen, 2001), which are considered to be major factors hindering commercial development. Therefore, to develop an economically viable industrial process, the focus of our study was on treatment time and acid concentration. Thus, the time saving potential of microwave heating led us to its application with acid extraction. The specific objectives of this study were to: (1) develop a new CCA recovery system based on the application of microwave energy, and (2) optimize reaction time, temperature, and acid concentration for the process.

Todd Shupe is the President of DrToddShupe.com and is a well recognized expert on wood-based housing and wood science.  Shupe worked as a  professor and lab director at LSU for 18 years and Quality Manager for Eco Environmental (Louisville, KY) for 2 years. He is active in several ministries including his Christian blog ToddShupe.com. Todd is the Secretary of the Baton Rouge District of United Methodist Men, Database Coordinator for Gulf South Men, and volunteer for the Walk to Emmaus, Grace Camp, Iron Sharpens Iron, Open Air Ministries, HOPE Ministries food pantry. Todd is currently preparing to be a Men’s Ministry Specialist through the General Commission of United Methodist Men.