Paper Mate Biodegradable Test

Paper Mate Biodegradable Mechanical Pencil Biodegradability Test

(Phew, that's a mouthfull)

Long term readers should recall that for the past year I have been putting the Paper Mate Biodegradable mechanical pencil to the test. Well 1 year is up so the test is over. Let’s just refresh our memories. The main body of the Paper Mate Biodegradable mechanical pencil is made from a special plastic which is claimed to be biodegradable. The Paper Mate website states

“Paper Mate® Biodegradable* products have been tested according to internationally recognized standards ISO 17556 and ISO 20200. Tests confirmed that, under normal temperature conditions found in soil/home compost, the product’s biodegradable components biograde(sic) in about a year.”

Not one to miss an opportunity for scientific investigation, I decided to put this to the test myself, and a year ago buried a Paper Mate Biodegradable mechanical pencil in my garden. You can read the previous postings on all this via these links:

• Paper Mate Biodegradable Mechanical Pencil Review
• Paper Mate Biodegradable Mechanical Pencil biodegradability test – The start
• Paper Mate Biodegradable Mechanical Pencil biodegradability test – 6 months

Right then, it is now early May 2011 and one year is up. As noted above, Paper Mate claim the pencil should biodegrade in soil in about a year, so let’s go out to the garden. The herbs and flowers are looking quite nice, especially those red capsicums (bell peppers) towards the far end.

Push aside the mint and parsley to find the Paper Mate stuck in the soil as a grave marker.

Now dig down a bit to find the body.

Here’s the body and the marker, fresh from exhumation.

Now let’s give them a good scrubbing in some lukewarm water with detergent to remove as much dirt and grime as possible.

Those barcode labels still look pretty good!

Where are the tips? That’s interesting. They were definitely buried with the main bodies but are now nowhere to be seen. I can only guess they have biodegraded away!? As for the main bodies though…well there doesn’t appear to be a lot happening. There’s no question the bodies are being eaten away by micro-greeblies and such. The parts stuck in the soil are no longer nice and smooth. They are rough and pitted, looking almost sort of fibrous. My photographic skills aren’t really up to the job, but hopefully the two images below will give you some idea.

It is interesting to note that the grave-marker pencil has only been attacked from the soil-line down. It is basically as good as new above ground level despite being outdoors for a year. Equally interesting is that the barcode label has protected the surface of the buried pencil. The body surface directly beneath the barcode label has not started to degrade like the rest of the body.

At the start of this little experiment the two test pencils weighed in at 16 grams. After 1 year they now weigh in at…14 grams. So they have lost 2 grams of material in a year. Most of that would be the two tips which have gone missing. I can only assume those much smaller sections with much greater surface to volume ratios have been eaten away quicker? Either that or grave-robbers.
Whilst there’s no question these pencils are starting to biodegrade, I really must question the statement that these pencils will biodegrade “…in about a year”. Personally I think my garden counts as “normal temperature conditions found in soil/home compost”.