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 Deep fried (Thermally modified) Eucalyptus regnans Timber Durability Trial

A trial to test the above ground durability of thermally modified eucalyptus, Kerikeri, 1 Jan 2012

Dean Satchell
Sustainable Forest Solutions
RD 1 Kerikeri 0294
(021) 2357554

Samples were from clear 100 x 25 Eucalyptus regnans from 18 year old Central North Island trees, from 3 trees (R, S & B). All timber samples were 250 mm long, dressed to 23 mm x 97 mm. 

One board was used to represent each tree, and cut into 250 mm lengths. Each piece was weighed after frying and control pieces (unfried) were weighed. Moisture content average 13%.

All samples deep fried in tallow ("dripping" purchased from local supermarket) in domestic deep fryer at approximately 200° C.

Four batches were fried. When the wood was first added the moisture in the wood caused frothing and overflowing of the fat. The lid could not be closed until the moisture had all fried off.

Fry #1 Fry #2 Fry #3 Fry #4
1.30 pm started frying
2.25 pm closed the lid
7 pm came out		 10.30 am start
11.30 am frying real good
3.30 pm came out		 3.38 pm start
8.38 pm came out		 11.39 am start (down to 190° C)
11.44 am up to 195° C
2.30 pm at 196° C
4.13 pm at 197° C
4.50 came out

Three fence posts were used, one fence post for each tree's samples (R, S & B). Eight samples were nailed to each fence post, representing 4 controls and one sample from each fry. The top of the top sample was 1.0 m from the ground and each sample was nailed below the sample above with a space of approximately 1 cm. A single galvanised nail was used to attach each sample.

Post R
Number Sample Weight before frying (g) Weight after frying (g) Distance from top of fence post to top of sample (cm)
1 control 250   16.1
2 R#1   225 27.5
3 control 245   38.5
4 R#2   220 49.5
5 control 260   60.5
6 R#3   225 71.8
7 control 250   82.9
8 R#4 245 220 94.4
Post S
Number Sample Weight before frying (g) Weight after frying (g) Distance from top of fence post to top of sample (cm)
1 control 290   21.9
2 S#4 290 255 33.2
3 control 290   44.3
4 S#3 290 260 55.5
5 control 290   66.6
6 S#2 290 260 77.5
7 control 290   88.7
8 S#1 290 250 100.0
Post B
Number Sample Weight before frying (g) Weight after frying (g) Distance from top of fence post to top of sample (cm)
1 control 290   21.0
2 B#3 230 225 32.3
3 control 265   43.3
4 B#4 255 240 54.4
5 control 275   65.1
6 B#1   220 76.5
7 control 270   87.4
8 B#2   220 98.6

Further controls

5 pieces were fried at 100º C for 10 minutes to provide controls that were soaked in tallow but not thermally modified, to check what if any durability the tallow alone imparts to the timber.

The 5 samples were nailed to the next post east of Post B.

Distance from top of fence post to top of sample (cm) Tree Weight before frying (g)
21.4 B 290
32.5 R 265
43.7 R 235
54.9 S 290
66.2 R 275

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