Thread: Microwave drying test - I'm wrapped!!

OK, per the previous Thread, I have conducted am experiment based on the 3 most popular drying techniques.

My methodology was as follows:

Panasonic Genius 1100w Microwave (a few years old).

3 blocks cut from 2 week old (therefore Very green) Manchurian Pear. Each was turned to a 145 x 55 blank of approx 1kg each

Green1.jpggreen2.jpg

A 1kg control block was cut from the same block and given a high temperature drying to provide a dry weight target indicator (handy that its winter here!)

control3.jpg

Block 1 was zapped on high for 2 minutes, weighed, left to rest for 10 mins the zapped again for 2 min on high, repeated until 2 identical weights were recorded.
Block 2 was zapped in exactly the same way except that the block was wrapped in T-shirt material - only removed for weighing purposes toward the end.
Block 3 was zapped on defrost for 4 minutes, weighed, left to rest for 10 minutes then re zapped on defrost for 4 min, repeated until 2 identical weights recorded.

Note. I left all 3 blocks to rest overnight (each lost around 40g during this cooling).

Results:
Block 1, 2 min High zap's UNwrapped. Starting weight 1021g Dry Weight 796g. Total moisture loss: 225g
Block 2, 2 min High zap's Wrapped. Starting weight 1028g Dry Weight 737g. Total moisture loss: 291g
Block 3, 4 min Defrost Unwrapped. Starting Weight 956g Dry Weight 734g. Total moisture loss: 222g

Control Block. Stove top dry. Starting weight 1020g Dry Weight 798g Total moisture loss 222g
(note that the control block was also zapped for 1 min on high to check that a "dry" weight had been achieved).

Dried1.jpgDried2.jpg

For the zapping I simply rotated from one block to the next. Interestingly each had a near identical number of zap's to achieve their dry weight.

control1.jpgCotrol2.jpg

As might be expected, the control block started to fracture in quite a number of places - though not as badly as I thought it would.
Interestingly, there were no visible cracks in any of the zapped blocks.
There was very little difference between Blocks 1 and 3. Both had similar weight losses and took the same amount of zapping to achieve their dry weight.

The biggest difference was Block 2 - the wrapped block. After being left to cool it recorded a substantially higher level of moisture loss. It also shrank and twisted quite substantially (check the pictures).

In my opinion therefore, the wrapped approach works best. Requiring the same amount of nuclear power as the other methods a drier timber is achieved - which in my experience results in fewer long term problems (twisting/cracking).

Cheers
Phil