Not your normal tarring question

[NYCivilWar]

Hello All,

****Let me start off by saying that I do not want this question to turn into a discussion on the hazards or potential hazards of using linseed oil. This has already been beat to death over and over again.

That being said, my question on tarring is in regards to finished appearance of a tarred piece of equipment. When you look at some original photos of knapsacks they appear to have a super glossy appearance. My question is, was this the case more than not? If you look at modern photos of original knapsacks they have a glossy look to them but not as glossy as some in original photos. See the Federal Echoes of Glory pgs: 212-213, or Confederate Echoes 202-205.

Would the "glossyness" wear off in the field, or did it depend on the manufacturer and the recipe they used?

I'm doing some tarring right now, and it does not have that super glossy finish to it yet, granted I have not put on the final coat, but just curious.

[Becky Morgan]

Re: Not your normal tarring question

Every tarred piece I've seen or handled has been somewhat less than glossy, apparently because of embedded dust that cuts the shine. I haven't handled anything that hasn't been de-crudded enough to be put on display. Fresh tarring on lines, tarps and such (maritime stuff) looks shiny, but I don't know how long the shine lasts without dust settling on it.

The question may be which units were most diligent about cleaning their knapsacks and such and what the conditions were at the time. It would likely be harder to keep a tarred item clean on a very hot, dusty midsummer march or a mud-splattering spring rain than it would in milder weather.

[Spinster]

Re: Not your normal tarring question

Based only on my own experience , the linseed had and held a certain gloss over about 18 months--not a high gloss, but I was working on a medium red base , not a black one.

At that point, all my plunder got in a flood and sand scoured the gloss off the pieces--and solved the residual 'sticky' I was still having. Canvas remained very water resistant.

[wade03]

Re: Not your normal tarring question

I have an original knapsack at hand, and after a carefully studying it and thinking on the matter I believe it was painted with one coat of thick black paint and left dull. It was never glossy, as even the inside parts are dull as well, and they really haven't been exposed to dirt or dust. It might be worth mentioning that this pack is dated 1865. I've also looked at a early war haversack and it was once pretty glossy, but the outside is now dull as it has been exposed to the dust over the years. Photos of the haversack attached. Hope this helps.

[CSchneider]

Re: Not your normal tarring question

I've changed the archival tissue paper that was wrapping an original unissued knapsack because it was soaking up oil (didn't do much, the new paper is still getting oily). Anyway, this thing is about as new as a 144 year old piece of gear can be, and while it has some shine to it, its defintely not much of a high gloss. I've managed to reproduce some glossy painted cloth before with heavy even top coat of blackened resin varnish, but that lasted only until I put the haversack on, took a step, and kicked up the tiniest bit of dust.

-Craig Schneider

[J.H.Berger]

Re: Not your normal tarring question

Craig, could you please post pictures of the original knapsack?
I am very interested in the finish.
I have amid war -late war knapsack which is actually falling apart although it was never used but that finish is abvsolutely dull with no trace of shine at any place. Honestly I think the finish/ shine varied from maker tomaker( recipe of paint) and even from run to run like indigo dyed cloth.

[NYCivilWar]

Re: Not your normal tarring question

Thank you everyone for your responses. This is exactly what I am looking for. If anyone has anything else to add please do!

[Curt Schmidt]

Re: Not your normal tarring question

Hallo!

Without doing painting tests, this is just a theory...

But I believe the difference in "gloss" may be due to the differences between CW Period linseed oil and modern linseed oil.

Meaning...

Modern "boiled linseed oil" is not really boiled. The flax seed is exposed to steam and then crushed (pressed). The oil is highly filtered to remove any plant waste. Then, purified to remove many of the substances such organic and inorganic phosphates that allow it to dry to a hard protective "shell" by heating it and forcing oxygen through it. Then other compounds are added such as mild acids or alkalis. And last metallic salts (usually cobalt octoate).

Curt

[Hank Trent]

Re: Not your normal tarring question

Modern "boiled linseed oil" is not really boiled. The flax seed is exposed to steam and then crushed (pressed). The oil is highly filtered to remove any plant waste. Then, purified to remove many of the substances such organic and inorganic phosphates that allow it to dry to a hard protective "shell" by heating it and forcing oxygen through it. Then other compounds are added such as mild acids or alkalis. And last metallic salts (usually cobalt octoate).

Out of curiosity, what do you think makes the most difference between period and modern boiled linseed oil? The temperature? The kind of metallic salts?

I've found a variety of metals recommended for producing boiled linseed oil in the period, so I don't know what was most common. Litharge is mentioned, but so is manganese, and even cobalt, at least experimentally.

I wonder if the modern way of not heating it as hot was due to experiments like this, from an 1869 source, which compares the "usual" way to a lower-temperature way.

...the painter wastes both good materials, fuel and time. He boils his oil too long, and maintains the temperature too high. The usual mode of preparing dryers is to heat the linseed oil in an iron pot until it appears to boil. The surface is skimmed from time to time, and after from three to six hours, about one-tenth, by weight, of litharge is added, and the heat is maintained five or six hours longer; or 100 parts of very old linseed oil is heated about six hours, when six parts of litharge and about three of burnt umber are added. The heat is continued six hours longer, when the liquid, after being left quietly to cool, is decanted. For the manganese dryer, the oil is heated at the so-called boiling point during five hours; peroxide of manganese is thrown in, and the boiling continued for eight hours. We have already seen that the boiling is not the formation of vapor, but the escape of gas-bubbles due to decomposition. [The author then describes experiments that showed heating linseed oil only to 100 to 176 degrees for only three to six hours while adding the manganese dried just as well]

So anyway, I guess I'm just curious what was the most typical metal(s) used for making boiled linseed oil in the period and what you think has made the most difference between period and modern linseed oil.

Hank Trent
hanktrent@voyager.net

[Curt Schmidt]

Re: Not your normal tarring question

Hallo!

"Out of curiosity, what do you think makes the most difference between period and modern boiled linseed oil? The temperature? The kind of metallic salts?"

Not a chemist, but...

IMHO, neither.

The greatest difference in appearance and function (anti-hygroscopic) lies not in the chemical additives but rather in the level and degree of the removal of (for lack of the correct terms) "resins" that impart the "hardness" to the Period linseed oil (sometimes refered to in Period arsenal papers as
"hard oil").

(While it may be an apples and oranges kind of thing, but IMHO the best information for this comes from the musical instrument as well as gunmaker side of treating wood. Although not the same as cheap military arms, typically, "boiled linseed" linseed was not the sole product but rather formed the base for various makers' personal varnishes by adding things to increase the anti-hygroscopic benefits lost when too many of the "resins" are removed from the linseed oil.)

IMHO, the rest is adding Period or Modern chemicals to improve the typically abysmal drying time of "raw linseed oil." (Often done in the Past with turpentine.)

Curt
Litharge of Gold Mess

[PVT.BEN MILLER]

Re: Not your normal tarring question

Maybe the gloss look is from the lenses of the camera. I don't know...... Just food for thought.