Re: question for waterproofing canvas

["Lawrence F. London, Jr." <lflondon@mindspring.com>]

On Wed, 21 Feb 2001 12:44:24 -0800, "Yaya Balinci" <yaya@telus.net>
wrote:

>
>I have been using double-boiled linseed oil from Recochem to treat the wood
>in my yurt. I think i will try rolling it on to the hemp canvas for the
>outer most layer to waterproof the canvas. I contacted recochem to see what
>they use for drying agents and this is what he told me:
>
>Does anyone have any idea what this is?
>
>The drying agents are transition metal salts of Naphthenate.

There used to be a medium-toxic wood treatment with copper sulphate in
it (would turn the wood greenish blue) called Copper Napthenate. This
may be what he is referring to. If your linseed oil has lead in it,
avoid it. Why would a drying agent be necessary anyway for the
purposes you intend to us it for? 

I would try heating/mixing: paraffin, beeswax, linseed oil (minimum
amount necessary) , pine (any conifer) sap and applying that - could
add a little turpentine to make it less viscous but smell/toxicity may
make that prohibitive. Heat this mixture in a large container, immerse
your canvas in it until saturated adequately; pull out and let dry,
preferable stretched out onto the yurt frame. When this is done and it
has dried apply many more coats to the outer canvas surface for
additional water/weather-proofing.

Here are alternative mixes usually used on wood:

<>
Mix 750 mL, 30 mL paraffin wax with enough mineral spirits or
turpentine to
make 4 litres.

Dip the wood into the mixture for a few minutes or apply with a brush.
Let
dry a few days before painting.

This is a US Dept of Agriculture recipe - supposed to protect for 20
years.
<>
Pine tar, linseed oil, and turpentine. Or just linseed oil and turp.
All highly flammable, but at least they smell good.
<>
3 c             Exterior Varnish
1 oz           paraffin wax (by weight)
3 1/4 qts.   Mineral Spirits, Turpentine, or Paint Thinner
(to make 1 gallon total)
<>
Half and half turpentine/linseed oil with 1-2 pints of pine tar/5
gallon mix
<>



Lawrence F. London, Jr.  ICQ # 27930345  
lflondon@mindspring.com  london@ibiblio.org  
http://www.ibiblio.org/ecolandtech