The Brown Filter Bag

We have received this lovely post from Rupert Brown of Brown’s Bushcraft who tells us the story of The Brown Filter Bags:

My name is Rupert Brown founder and owner of Brown’s Bushcraft based in the South West of France. In addition to teaching bushcraft I am also the creator of The Brown filter bag. Along with many bushcrafters, I used Millbank bags for coarse water filtration and recommended these to students on my courses. The Millbank bag was used by the British military worldwide since the 1940’s. It was issued to every soldier along with chlorine tablets to provide a simple and effective means of treating dirty water. Millbank bags used to be readily available from army surplus stores. But when the army stopped using Millbank bags some years ago, they became more and more difficult to come by.

Millbank bag

The original millbank bag

This was my initial motivation to create the Brown bag. Students would often come back to me saying they are finding it hard to find stocks of Millbank bags, is there an alternative? The Millbank bag is such a simple, effective solution to filtering dirty water. I didn’t want to remove it from part of the watercraft teaching due to lack of stock.

In late 2011 I decided to research and possibly create a replacement for the army Millbank bag. I made many test filter bags and tested many different weights and weaves of canvas but didn’t find a canvas that performed as well as the original Millbank bags. This led me to try and source some old stock of the original Millbank canvas. I contacted all the companies in the UK that used to make the bags for the army to see if there were any old canvas stocks. After much research, it concluded that there was no original canvas to be found. Fortunately, during my search, I was able to find the original manufacturers of the Millbank bag canvas, a company based in the UK that weaves specialist technical fabrics for professional and military use. The canvas is now woven to order uniquely for the Brown bags. It is woven to the same specification and by the same company that originally made the canvas for the Millbank bags, only in a more subtle brown colour (rather than the original turquoise), and not treated with Cuprammonium. Working closely with the company they were able to explain the original Millbank bag was treated with Cuprammonium as an anti-rotting agent. It was removed towards the end of Millbank bag production due to it being potentially harmful.  Once I had the correct canvas woven that was the first part of the project completed.

The Brown Bag

The Brown Bag

I then needed to find a manufacturer for the bags. For me it was important the bags were made within Europe, this would ensure regular contact and quality control. After trying a number of different manufacturers and rejecting the samples due to faults and inconsistency in the finished bags, I found the current manufacturers that are UK based and the quality and finish on every bag is excellent. The bags are double stitched with rot-proof thread, firstly inside then secondly on the outside to ensure a durable seam. The next part was designing a label and to format clear instructions for the rear of the label. Finally, the paracord was sourced and sent to another company to cut to length and crimp the brass ends onto the cord. A swing tag was designed and added to the bags with details of the bag and how to use it.

The Brown Bag

The Brown Bag

The whole process took nearly two years as I wanted to ensure the Brown bag was made to a high standard before being launched onto the market in January 2014. I had to be confident people could rely on the Brown bag as a reliable means of coarse filtering water with little risk of it failing or falling to pieces when needed. Once I had a completed bag I contacted the London school of hygiene and tropical medicine to discuss running some experiments with the bag. The Brown bag is not designed to remove pathogens, but we decided out of interest to run some experiments with the bags. A muddy solution was mixed with E. coli bacteria and microscopic fluorescent beads to mimic Cryptosporidium cysts and passed through the Brown bags. The collected filtered water still had the E. coli bacteria present, but the microscopic beads were reduced by two thirds. So although still not safe for drinking the load for the sterilisation process was reduced. With all the research and attention to quality, this now ensures a plentiful known source of new filter bags that perform as well as the army Millbank bags. The Brown bag is a 100% UK product with both the canvas being woven in the UK as well as the production of the bags.

The Brown Bag

The Brown Bag

The Brown bag is a lightweight, compact, durable coarse water filter with an unlimited filtering life. It is easy to use and carry and will enable dirty/cloudy/turbid water to be filtered prior to disinfection. The Brown bag is also an effective pre-filter when using mechanical filters to reduce clogging and extend the filtering life of mechanical filters.

The Woodlore team are great ambassadors for the Brown bag as they use them both in their personal kit as well as incorporating them into the teaching at Woodlore.

– Rupert Brown

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