Natural Waterproofing (Results)

Some time ago in November 2013, we finalised our natural waterproofing experiment in collaboration with ABARI. Because I had to leave Nepal and relocate to Thailand, it took me a little while to look into the data in detail and publish this new post.

When the results came out, thanks to Benjamin Ervin’s collaboration, we got very excited. Some of the results defied expectations.

The experiment setup comprised 14 different waterproofing techniques on bamboo, mostly using natural products, but also few commercial / industrial products to compare with, together with 1 plain bamboo sample. The samples were duplicated, one for outdoor exposure (as would be expected for shingles or other external surface) and other samples were immersed in water to really push the waterproofing to its limits.

Controlling the experiment results consisted in checking the state of the samples after 4 months of exposure to their respective environment and measuring their moisture content with an electronic moisture content reader. For samples in water, we measured the moisture content twice, once when removing the sample from the water medium, another time 30 minutes after to see how fast the sample had dried.

The data has been collected into the following table:

Reference Number Description Outdoor Water
Look Moisture Test in % Moisture Test in % Look
0 min 30 min
1 Gum Arabic + Ethanol bad 9.1 100 100 bad
2 Silicone 100% good 16 100 100 bad
3 Silicone 30% good 11.1 100 100 bad
4 Black Japan good 14.8 100 100 good
5 Shellac + Ethanol bad 14.5 100 100 bad
6 Saal + Turpentine ok 9.6 69.5 80 bad
7 Melted Shellac bad 20.1 52 55 bad
8 Melted Gum Arabica bad 11.8 57.8 51.8 bad
9 Sealer bad 20.8 90 100 bad
10 Charred good 9.2 42 36 1
11 Bee’s Wax bad 16.6 100 100 ok
12 Linseed Oil good 10.1 42.7 32.4 ok
13 Linseed Oil (Boucherie) good 14.8 32.8 26.2 ok
14 Fired / Smoked Bamboo ok 16.2 49 44.4 ok
15 Plain (Control) ok 18.4 100 100 ok

The PDF version of this table might offer a better overview with the highlights of interesting results: OB-ABARI Natural Waterproofing Results Overview 2013

Starting with the bad news, it seems the Gum Arabica, Shellac and Wax samples did very bad. The industrial products (silicone and sealer) did very poorly too (surprisingly). Black Japan was a real disappointment for me, even though it uses crude oil, it seemed to be a reliable technique at first, but results show it was not efficient. The fired / smoked bamboo shows interesting results, I would like to reserves my doubts about this one because I am not too sure we did this the right way. It would deserve another chance in my opinion.

Now the good news: it seems the interesting results are the following:

  1. Charred bamboo
  2. Linseed Oil
  3. Linseed Oil (Boucherie)

Charred bamboo is the most impressive by far, it looks good and it was simple to achieve. I think the three candidates above need to undergo further testing with more samples.

I feel very excited about this experiment which I think was quite successful considering our means and scope. I hope we can soon experiment further and give more interesting results.

Now, the picture show:

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