Graduate Program

Sustainable Energy and Technology (dual degree)

Degree Name

Master of Science (MS)

Semester of Degree Completion

Spring 2023

Thesis Director

Isaac Slaven

Thesis Committee Member

Barbara S. Carlsward

Thesis Committee Member

Steve Wright


Developments in regulations concerning the use of CBD products as therapeutic remedies have allowed the global cannabidiol (CBD) market to take off within the past five years. Despite producers of CBD oil wanting to optimize their methods and increase product yields, several waste streams still exist. During the winterization phase of the ethanol extraction process, CBD oil is cooled and filtered so the fats, waxes, and lipids from the Cannabis sativa plant can coagulate and be removed, creating a purer oil with higher potency but contributing to the 58% (crude weight) total loss that occurs throughout the process. The removed waste product is a black tar-like substance that currently holds no value or purpose.

Upon initial observation of this material, CBD tar presented similarities to other plant tars such as creosote or bitumen—both of which had been historically used for waterproofing and sealing. Currently, however, natural sealants that are commonly used include boiled linseed oil and hempseed oil. If CBD tar could perform similarly to these materials and show an equal ability to reduce water absorption, potential use for this waste product could be determined.

To assess this, a saturated solution was created by dissolving CBD tar in Acetone in a ratio of 75g:150ml. The three treatments (CBD tar, boiled linseed oil, and hempseed oil) were applied to a variety of hardwood, softwood, and composite wood samples in a series of either one, two, or three coats. Southern yellow pine and white ash coated with the treatments were soaked in water for either a 1-hour or 3-hour period to gather data on water absorption of hardwood and softwoods. Composites such as HempWood®, oriented strand board, and particle board were soaked in water for three 24-hour periods to collect data on linear expansion and absorption.

Qualitative observations such as the material’s ability to penetrate wood, as well as color change, were also included in this study.

The results showed high potential for further assessment of the material through a series of one tailed t-test comparisons that returned highly significant differences between applications of CBD-tar and no treatment in addition to CBD-tar against the manufactured treatments for solid wood. CBD-tar applied to composite wood OSB, and particle board also showed highly significant results against no treatment warranting further inspection of the materials ability to reduce linear expansion due to water absorption. Results from this experiment show that additional trials and analysis on alternative features of wood finish such as durability and ease of application would be worthwhile. Potentially, this waste byproduct could be transformed into a valuable resource that allows manufactures get more out of their processes by closing the loop on one waste stream.

Available for download on Thursday, May 02, 2024