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Real World Differances Between Boiled Linseed Oil and Stand Oil?

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Forum topic by Lovegasoline posted 08-13-2020 07:00 PM 457 views 0 times favorited 4 replies Add to Favorites Watch
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Lovegasoline

161 posts in 891 days


08-13-2020 07:00 PM

I’m curious regarding the various oils.

I just bought a quart of boiled linseed oil yesterday at the big box store. Although I’ve used a large variety of linseed oil in my life, I’ve never used BLO before as I’ve always considered it an inferior product (I’m an artist so that bias is attributable to archival concerns whether accurate or not). At present I probably have 10 different types of linseed oil here all processed differently (running the range from true raw pressed linseed, copolymerized, vacuum bodied, sun thickened, processed to various acidity levels, w/driers added, etc. etc.).

My experience with Stand oil (in oil painting) vs. most other linseed oils is that it dries to a much higher enamel-like gloss and is more viscous out of the bottle. Stand oils are typically not formulated with driers (I also have several oil driers formulated from different metals). I often see Stand oil suggested as interchangeable with Boiled Linseed Oil in wood recipes. I realize that manufacturers will incorporate different ingredients, quantities, and processes to formulate their product and may not necessarily disclose all of these to the consumer, regardless of the various regulations in place (for ex. various countries have differing requirements regarding ingredient disclosure and trying to get an accurate breakdown can often involve an investigation resembling a research project or detective work … and in many cases is simply impossible). What, if any, is the perceivable difference between Stand Oil and Boiled Linseed Oil either used alone or in an oil/varnish blend?

I have a few Stand Oils on hand including one from Kremer Pigments which is high quality German artists’ materials/chemicals supplier.

BLO is much cheaper. But the driers would be beneficial as an application convenience. I can see the argument against using metallic driers (which I assume many BLOs contain) for food contact and environmental concerns. But other than these, what’s the real world difference on the wood?

-- “It is the beginning of wisdom to recognize that most men are fools and knaves, but it is the end of wisdom to embrace that vision.” -Arthur Kleps


4 replies so far

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CaptainKlutz

3604 posts in 2347 days


#1 posted 08-13-2020 11:23 PM

Differences are subtle:

Modified linseed oils

Stand oil
Stand oil is generated by heating linseed oil near 300 °C for a few days in the complete absence of air. Under these conditions, the polyunsaturated fatty esters convert to conjugated dienes, which then undergo Diels-Alder reactions, leading to crosslinking. The product, which is highly viscous, gives highly uniform coatings that “dry” to more elastic coatings than linseed oil itself. Soybean oil can be treated similarly, but converts more slowly. On the other hand, tung oil converts very quickly, being complete in minutes at 260 °C. Coatings prepared from stand oils are less prone to yellowing than are coatings derived from the parent oils.[47]

Boiled linseed oil
Boiled linseed oil is a combination of raw linseed oil, stand oil (see above), and metallic oil drying agents (catalysts to accelerate drying).[47] In the Medieval era, linseed oil was boiled with lead oxide (litharge) to give a product called boiled linseed oil.[48] The lead oxide forms lead “soaps” (lead oxide is alkaline) which promotes hardening (polymerisation) of linseed oil by reaction with atmospheric oxygen. Heating shortens its drying time.

Source: https://en.wikipedia.org/wiki/Linseed_oil

In practical terms:
Generic BLO sold for wood finishing typically has high levels of organo-metal drying agents. Modern day BLO tends to use cobalt or manganese metal drier compounds, which are safer than lead or tin compounds used as recently as 20-30 years ago.

There are a couple of BLO finishes, such as Tried and True Danish Oil; which does not have the ‘unsafe for human consumption’ metallic driers. While mfg does not disclose the details on process or drying agents, I believe it acts more like stand oil with weaker/safer ‘metal’ compound, then cheap lower viscosity BORG brand BLO optimized for lowest cost. But I have no proof, only a vague theory based on my use of T&T products?

There is a constant source of debate regarding drying oil finishes being safe for human consumption. The primary argument is that the driers are present in parts per billion levels, and once the linseed oil is polymerized; it is very hard to liberate the metal complexes into your food. Sure it is possible using chemistry that destroys the finish and ruins the wood underneath, but would you eat food that destroys the plate, bowl, or cutting board??
This debate will likely rage on here in this thread again, after these sentences ‘poking the bear’ awake. :-0)

Not an expert. #IAMAKLUTZ and occasionally an amateur polymer chemist. YMMV

Best Luck with

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

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Lovegasoline

161 posts in 891 days


#2 posted 08-14-2020 02:40 AM

Ok.
Yeah Captain… I’m likely even more of an amateur and most definitely not a chemist.

I’ve tried my hand at making my own drying oil (aka ‘Black Oil’) with raw cold pressed linseed oil heated with basic lead carbonate … which is then utilized as an ingredient and combined with a resin (mastic crystals dissolved in turps) to obtain a fascinating substance with amazingly unique thixotropic qualities. It requires the lead (litharge or basic lead carbonate) to work. Lead is king.

There’s also this stuff (completely different in behavior to the modern industrial pigment manufacturing process with its homogenized pigment particle sizing):


[Stack or Dutch process lead white (Flake White) is made by taking strips or sheets of lead and rolling them up into porous clay pots where they are suspended above weak acetic acid (vinegar). The pots are then buried in fermenting horse dung or cow manure producing heat and CO2. The surface crust (flakes) are scraped off and then washed, dried & ground into a powder.

I’m not going to be eating this project, injecting it, or powdering and insufflating it.

So disregarding the technicalities …

... and returning to the question. Fleeing momentarily from the coarser generalities and blurry intoxication of expeditiousness in order to embrace the nitty-gritty of the wood finisher’s craft:
what’s the real world difference in performance and appearance?

-- “It is the beginning of wisdom to recognize that most men are fools and knaves, but it is the end of wisdom to embrace that vision.” -Arthur Kleps

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SMP

2476 posts in 758 days


#3 posted 08-14-2020 04:19 AM

I’ve made my own BLO from raw linseed oil from Blick, and heating it up in a pan outside on my grill. Have also used flaxseed oil from health food store. I have jars of it plain and mixed with pure beeswax. This way i know exactly what’s in it. I followed Wood by Wrights vid, super easy and works great:

https://m.youtube.com/watch?v=VtETzSg4LcE

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CaptainKlutz

3604 posts in 2347 days


#4 posted 08-14-2020 06:58 PM

... and returning to the question.
.
what s the real world difference in performance and appearance?
- Lovegasoline

Have never read of anyone using stand oil without addition of Japan Drier for finishing? Have never used straight stand oil for finishing. Only used stand oil as plasticizer in a polymer. So have no first hand data on differences?

Assuming for a moment the T&T Danish oil IS a BLO with higher stand oil component, and having used both; can make this comparison: After long term use, Kleenstrip/Sunnyside brand BLO coated surfaces tend to be more brittle and show cracks more readily, than the T&T Danish oil.
My assumption (right/wrong?) is the viscosity differences between BLO and T&T products are part of reason. The T&T danish oil slightly higher viscosity means it likely has longer polymerized chain length, which translates into a more flexible polymer once cured. But my sample size is only a couple small bowls made with each product.
YMMV

Best Luck finding an answer.

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

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