[TheForge] Other thoughts on: oil/wax finish, blackened steel

Sun Oct 24 08:40:06 EDT 2010

As noted in above replies, Japan drier does contain metals, possibly
including cobalt.  See the Wikipedia article or MSDS sheet (for a
particular product) for details.  I cannot comment on Brimson's
assertions about the degree of hazard these metals pose, as I am a
chemist, not a toxicologist, but, it is a given that one does not use
"boiled linseed oil" (containing Japan-type driers) on food-contact
articles.

In the latter regard, let me repeat what I've said many times on this
forum:  Linseed oil is not a whit better (and it is a LOT more
expensive) than any other polyunsaturated oil when it comes to HOT
finishing an iron article.  Develop the scale on your piece by heating
to red and cooling to black.  Apply polyunsaturated (cooking or salad)
oil when the iron is hot enough to smoke the oil a little, but not a
lot.  Or, apply a thin coating of the oil to cold, black iron, and
bake at 350*F-400*F for an hour.  A very  nice, shiny black finish
results.  This is exactly the procedure used for "seasoning" cast iron
cookware.  It provides some protection from rusting, but will not last
long outdoors.  What it is, really, is a dark brown dried oil over a
black scale.  If you put an oil coat on shiny steel, it will look dark
brown (which usually is not what you want).

So, what I proposed in an earlier post is an experiment I've yet to
try myself:  Add firescale as pigment to the oil and apply it hot.
Carbon black would work for sure as such a pigment, and is suitable
for stove blacking (which is mostly carbon black of one sort or
another), but might leave an undesirable "marking" surface to some
objects.  Fire scale is MUCH harder and less likely to mark.  But this
idea is yet untested.

By the way, I consider the key ingredients of stove blacking to be
pigment (carbon) and vehicle (oil).  Turpentine is to thin the mix,
and is irrelevant and undesirable if it is to be applied hot.  Waxes
might provide a harder surface, or a shinier one, but I doubt it --
the baked oil is fairly impervious and quite shiny.  Think "dried oil
paint" to get the image.

And as long as it is understood that polyunsaturated oil must be baked
to set properly, then there's no need at all for Japan drier in the
mix.

Another aside -- Carbon compounds themselves can be quite toxic, and
"carbon" from unknown sources may contain oxygen and nitrogen in its
chemical constituents (to say nothing of outright contaminants) that
increase the likelihood of toxicity.  Pure graphitic carbon is safe
because your body would never absorb it, but a black compound could
contain anything and probably does.  (Lampblack, for example, is a
suspect carcinogen.)  If you really wanted to assure the safety of an
unknown carbon black material, you'd have to take some considerable
trouble with it.

Activated (baked) charcoal is probably the safest by far, as its
origin is known and the activation process drives off most of the
small molecules.  (Activated charcoal is sold at the drug store as an
antiflatulent, and is often used to absorb other ingested poisons.)
Activated charcoal is the only "black" I would suggest you ever add to
anything that will be in contact with food.  There may be other safe
"blacks", but I don't know them.  All this worry is probably
excessive, but since the potential toxins are so easy to avoid, you
might as well know about them.

On Sun, Oct 24, 2010 at 12:05 AM, Cheryl Brimson <cbrimson at me.com> wrote:
> If you have any questions about toxicity, do what I've done for years, check the manufacturer's MSDS sheet.  All products, especially manufactured chemicals, have to be able to show what active ingredients and physical/physiological characteristics they possess.  I looked up the MSDS for Dynamic Mfg.'s Japan Dryer and Boiled Linseed Oil, and you have more toxic products in either spray paint/polyeurethane varnish or paint remover.  I have known a few people who suffered from acute sensitivity to cobalt from grinding carbide tool components in progressive dies, but that degree of sensitivity is rare.  The fumes from using arc welding rod or the scale you wire brush off forged steel is probably more harmful; as is the dust from the coal or coke used to forge with.  The key is to use a mask to contain the dust and to have adequate ventilation. Use gloves to protect your skin from contact dermatitis and you are probably fine.  FYI dryers or accelerants for oil based finish produc
>  ts generally do not contain "solids" but are "thinners" such as gum turpentine or isopropyl (denatured) alcohol.  All of which is fine, unless you are going to try to drink the stuff.  Keep a bottle of Scotch or Captain Morgan on hand  for that.
>
>
>
>
> On  Oct 23, 2010, at 10:20 PM, Mike Spencer wrote:
>
>>
>>> ...I've been warned that the dryers in "boiled linseed oil" and
>>> japan dryers are capable of giving you heavy metals poisoning...
>>
>> I think (but can't immediately confirm) that "Japan drier" has become
>> a generic term for several kids of drier.  Cobalt is used in several
>> brands of driers.  In addition I've seen an allegation that "boiled"
>> linseed oil contains "arsenic, beryllium, chromium, cadmium and
>> nickel" as drier constituents.  Bleee.
>>
>> Years ago, a smith here called the makers of a brand of boiled linseed
>> oil sold here and asked about using it on food prep utensils.  The
>> company rep emphatically urged him not to do that, but to use "raw"
>> linseed oil. The rep confirmed that "boiled" isn't boiled but has
>> driers added.
>>
>> So I just stay away from "boiled" linseed.  For a railing or exterior
>> paint it's probably fine but why mess around?
>>
>> - Mike
>>
>> --
>> Michael Spencer                  Nova Scotia, Canada       .~.
>>                                                           /V\
>> mspencer at tallships.ca                                     /( )\
>> http://home.tallships.ca/mspencer/                        ^^-^^
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-- 
Bruce
NJ