Hit the waves: can an ancient method for waterproofing surfboards stand up to modern techniques?

What's the best way to waterproof a surfboard? When ancient Hawaiians invented surfing sometime between 1500 B.C. and 400 A.D., they didn't have modern waterproofing varnishes to protect their wooden surfboards. So they looked to nature for help. The ancient surfers discovered that substances produced by the kukui (koo-KOO-ee) tree make an excellent surfboard varnish.

Unlike in the past, today's method for keeping surfboards in top form is far from natural. Many of the chemical varnishes used on modern foam-and-fiberglass surfboards contain ingredients that are harmful to the environment, says 15-year-old Robert Zane. The chemical acetone, for example, can damage the lungs if inhaled in large amounts. "So surfboard makers wear gas masks to protect themselves," says the 10th grader from Honolulu, Hawaii.

The environmentally friendly ways of the ancient Hawaiians inspired Robert to wonder: Could the kukui tree substances once used to keep surfboards from getting waterlogged stand up to modern waterproofing varnish for wood? If so, the natural product could serve as a "greener" alternative.

Two years ago, Robert set up a science experiment to test his idea. His careful data collection, along with detailed charts and graphs, wowed the judges at the Discovery Channel Young Scientist Challenge 2005. They awarded Robert a spot as a national finalist.

SECRET FORMULA

Before Robert could begin his experiment, he had to research the steps taken by the ancient Hawaiians to waterproof their wooden surfboards. He found out that he could reproduce their method by doing the following:

Cut open a kukui tree branch and strip the inner parts of the branch with a vegetable peeler. Then use a hammer to pound the resulting wood shavings. This squeezes out kukui tree sap. Add a small amount of charcoal to the sap and stir. Apply a layer of the mixture to a wooden surfboard. "The sap contains linoleic acid, which helps plug microscopic pores in the wood that water could soak into," explains Robert. "The charcoal is mainly used for staining the surfboard." Finish by sealing the surfboard with a protective coat of kukui nut oil, which is available at specialty stores.

SURF'S UP

To find out if the ancient waterproofing method stands up to modern varnish, Robert constructed nine mini surfboards out of koa wood. "It's the same type of wood that the ancient Hawaiians used to create their surfboards," he says. Then, he used permanent ink to mark each board with a number from one to nine.

Robert assigned the boards numbered one through three to group A, the control group. He left these boards unvarnished and used them as a standard against which the varnished boards would be compared. Robert treated the boards numbered four through six, or group B, the ancient Hawaiian way. He covered the three remaining boards, or group C, with a store-bought chemical waterproofing wood varnish.

Next, Robert weighed each surfboard with an electronic scale. Then, he placed each group of boards into a separate plastic tub filled with seawater. Robert knew that the least-efficient waterproofing method would allow more water to seep into the wooden surfboards over time. And the more water the mini surfboard absorbed, the heavier it would become.

DIVE INTO DATA

Robert soaked the boards for eight hours, weighing them every hour. Then he allowed the boards to soak for an additional 12 hours before weighing them again. He waited yet another 12 hours before the final weigh-in. "I kept the surfboards in the saltwater for a total of 32 hours," Robert says.

Since Robert's experiment required taking several measurements, he had to be organized to keep track of his variables, or the characteristics in his experiment that change or could be changed. So he created a data table. This table contained rows and columns, which Robert filled in with the weights of his mini surfboards. (see table, left).

When he had finished collecting data, Robert used the information to calculate the average percentage weight increase for each group of surfboards. He decided to create a bar graph to display these results (see graph, above). "This graph helps explain how the groups compare to each other," he says.

First, Robert labeled the graph's x-axis with the independent variable, or the factor that is changed on purpose. For his experiment, the independent variable is the waterproofing method of each surfboard group. Then he plotted the percentage weight increase of the boards along the y-axis. That is his experiment's dependent variable, or the factor that responded to the change in the independent variable.

ANCIENT WISDOM

Robert found that on average, the surfboards treated with kukui tree products weighed slightly less than the boards covered with commercial varnish. This meant that the ancient Hawaiian method of waterproofing wood was slightly more effective at repelling water than the modern way.

Robert also found that all the surfboards--even the unfinished ones--turned their tubs of water brown. The substances from the wood, as well as both types of wood finishing, leaked into the water over time. In large amounts, the chemicals contained in commercial varnishes could be polluting. "It's not very desirable to have them spread into the water," says Robert. "Because kukui nut oil is natural--and [even] edible--it doesn't pollute the water as much as the commercial varnish."

Wooden surfboards are rarely used today. So Robert says that his findings won't clean up the surf industry much. But he says his project can help the environment in other ways: "Wood products that are left out in rainy conditions, such as patio furniture, can be waterproofed with kukui [tree products] instead of commercial varnish."

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Learn more about the kukui tree, Hawaii's state tree, at: http://apdl.kcc.hawaii.edu/ ~ahupuaa/botany/other/kukui.thm

Bar Graph

Robert calculated the average percentage weight increase for each group of surfboards. What is the approximate difference in percentage weight increase between Group A and Group B?

[GRAPHIC OMITTED]

Data Table

Robert collected data for nine
surfboards. This table shows the
results for three of the boards.
Which of the boards below gained
the most weight over time?

WEIGHT OF SURFBOARDS
OVER TIME (IN GRAMS)

Hour   Board 2   Board 5   Board 9

0        50        45        50

1       53.5       46        51

2        54        47        51

3        55        47        51

4        55        47        51

5        55        47        51

6        56        47       51.5

7        57        47        52

8       57.5       48        53

20       60        48        54

32       63        49       54.5