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How to make your own wool insulation

Page history last edited by Deanne Bednar 9 years, 11 months ago

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How to make your own wool insulation . 

A. by Janine Bjornson a natural builder, practitioner and educator, trained in 1996 by Cob Cottage Company ! 



Q: I have interest in trying to make my own wool insulation. I have a source of wool and would like to know how I might process it to make it usable. Do you know anyone who has had success with this process?

A: Over the years I have heard of many people that have dabbled in using wool for insulation. I cannot say that I have heard of one particular technique that is tried and true. I will give you the most clear method that I have heard of as follows:

1) Clean wool. This means that you need to remove any dirt, debris, and lanolin. There are various ways to clean the wool but you want to make sure that the method you choose does NOT felt the wool. Use COLD water to clean the wool, not warm or hot. You may try anything from putting the wool in burlap sacks and sinking them in the river with the cold water rushing over them to clean the wool. Or you may put the wool in front loading washing machine set on the 'gentle' cycle. Do NOT use the top loading machines or you wool may turn to felt. You may use an industrial detergent to clean the wool in the machine. You will know that the wool is clean and the lanolin is removed because the wool will feel soft like a wet wool sweater and your fingers should not stick together after touching the wool. If your fingers feel sticky, there is still more lanolin in the wool that needs to be removed.

2) Treat with Borax. You want to treat the wool with Borax (commonly sold as "20 Mule Team Borax Laundry Additive") to repel insects. Borax is also used as a fire retardant. If you are using the washing machine to clean the wool you could add the Borax instead of fabric softener. Otherwise dissolve Borax in hot water to make a solution and spray on the wool as you lay or hang it to dry. Do not rinse it out. Unfortunately, I haven't been able to find out how much Borax you should use.

3)Card the wool. You now need to card the wool (when dry) to fluff it up creating air spaces between the fibres which will give it loft and greater insulation value. Remember, things that are insulative are light and fluffy like a down quilt. You may be able to find someone with a carding machine, otherwise you will need to card it by hand.

4) Make batts.You can now get strips of kraft paper to attach the wool to. This will hold the wool in place when you put it in a wall cavity. If you are placing it between 2 x 4's as in standard construction practices, you will want to cut strips of kraft paper 16" wide and as tall as your walls (for example). Spray the kraft paper with adhesive and lay down your carded wool onto the kraft paper. It is important to use some kind of system like this so that the wool insulation will not slump and settle in your wall. If it does, you will lose the insulation value that you were trying to create. You will also have air spaces at the top of your walls that will transfer heat or cold through the walls.

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