Mixing Stockholm Tar / Boat Soup

[mrkgllsp]

I'm looking for some insight to mixing up 'boat soup' and tips about working with Stockholm tar in general.

I tried the basic 1pt Tar; 1 pt Turpentine (gum); 1 pt Boiled Linseed Oil.

The tar just won't stay in solution or mix well. It quickly collects at the bottom of the jar, and when brushing the 'mixture' on wood, I get a lot of specs and blobs of tar

I tried using a double boiler to warm the tar which really helps - for a while, but the tar drops out when it cools down to room temp. Is there a way to get it to emulsify or mix well?

I'm using Stockholm tar from Davey & Co.

Any advice would be greatly appreciated!

Mark

[John Husky]

Re: Mixing Stockholm Tar / Boat Soup

I made a batch with Tung oil, Turpentine and Bickfords Pine Tar and a capful of Japan Dryer from the feed store. It mixed easy and I haven’t had any problems with it for over a year. Looks great, smells great and dries pretty quick. I would try mixing the tar and Turpentine together first in case the oil is causing issues.

[mrkgllsp]

Re: Mixing Stockholm Tar / Boat Soup

The tar I have is really pretty thick - like tar! Is that the consistency of the Bickfords?
Thanks for the tip.

[swoody126]

Re: Mixing Stockholm Tar / Boat Soup

goto Tractor Supply and get their PINE TAR

as above ... equal parts

tar, BLO & real turpentine

some will add oil based varnish and some will use a true Tongue Oil either one providing a harder finish

a splash of Japan Drier makes the stuff kick off a bit faster

when i looked up Stockholm Tar the answer was that it is "an especially high grade of pine tar"

i'm wondering if the "better" product could be causing the issues you are experiencing ?

or if the turpentine you are using could be the culprit ?

sw

[mrkgllsp]

Re: Mixing Stockholm Tar / Boat Soup

I ordered some of the Bickmore pine tar and will experiment with the turpentine. It'd be a shame if the Davey's Stockholm tar is not useable. Wondering if shipping in the cold weather can damage it.

In any case, thanks and I'll report back when I get Bickmore.

Thanks.

[Thad]

Re: Mixing Stockholm Tar / Boat Soup

Forget the turps and use raw linseed oil, the double boiler is necessary to get the tar to mix with the oil.

[Lemsteraak]

Re: Mixing Stockholm Tar / Boat Soup

Love this talk of tars, oils, soup, sounds so salty but seriously, tell me the reason why you want to add Pine Tar in your boat soup? What benefits does it add? I can see a downside, it will really darken the mix. My other question is why use boiled linseed oil rather than a just a nice pure raw linseed oil? I really should be asking, what is your application?

[John Husky]

Re: Mixing Stockholm Tar / Boat Soup

Pine tar is used as an antibacterial for horse hooves. For the same reason it has value as a wood preservative. Probably a debatable point, but it is cheap insurance. I use it to seal the wood on my boat during the building process which should take years. I find linseed to be less desirable than Tung oil because it harbors mildew. The Bickmore brand is dark, no question. But it looks good to me.

[jseymour]

Re: Mixing Stockholm Tar / Boat Soup

Your tar might not be the problem. In addition to good 100% pine tar such as you have, or that sold by Auson, use good raw linseed oil, and good turpentine. Mix it in three parts to start, and strain it through a nylon stocking or something like that. Dip from the top, and leave the sediment at the bottom. Add pine tar at the end of the season, strain it, and let it sit.

Tars used for hoof dressing contain chemicals that will interfere with the process, as does boiled linseed oil.

There are some good threads here. I think that this is one of the best, especially the comments by Ryden:

http://forum.woodenboat.com/showthread.php?148972-Boat-Soup

There are also a couple of articles in Woodenboat Magazine that are really helpful.

[mrkgllsp]

Re: Mixing Stockholm Tar / Boat Soup

I have a couple reasons for using the Stockholm tar mixture.

First, I may use it to coat the underside of some resurfaced floorboards on an open boat. I'm not sure if it's the route I'll take.

Reason two is just plain curiosity in something that's been so deeply tied to the history and aesthetics of sailing.

As a relative beginner, I still fine wood finishing a bit of a dark art of techniques and infused with much subjective preference, so I'm embracing the idea of 'experience begins by doing". I did get a copy of "Understanding Wood Finishing" by Bob Flexner which I found very useful.

As for linseed oil, is there more to the difference of boiled vs. raw than the additives or oxidation for quicker drying?

Either way, I need to figure out why I wind up with a blob of tar in a jar of oil and turp. More heat?

I appreciate the conversation!

[David Satter]

Re: Mixing Stockholm Tar / Boat Soup

http://tarsmell.com/index.html Good info here!

[jseymour]

Re: Mixing Stockholm Tar / Boat Soup

I have a couple reasons for using the Stockholm tar mixture.

As for linseed oil, is there more to the difference of boiled vs. raw than the additives or oxidation for quicker drying?

Either way, I need to figure out why I wind up with a blob of tar in a jar of oil and turp. More heat?

I appreciate the conversation!

The difference between boiled linseed oil and raw linseed oil is that boiled linseed oil has drying agents and other additives, and raw linseed oil does not. Boiled linseed oil will harden and flake, raw linseed oil gums but does not flake. Remove any excess blobs with a scraper.

I have never had to heat the mixture. Usually, when I put on my rub and cap rails and other things in the spring, the sun heats the surface enough to warm it. Good boat soup has the consistency of maple syrup, so it will be easy to brush on. Too easy, actually, but you can mask it with plastic wrap, or wipe it off with turpentine or Goof Off.

I haven't added tar to my boat soup in a few years. Each spring, I just add a 50-50 mix of raw linseed oil and turpentine to the can, which is gradually making the mix the color of whiskey.

[Lemsteraak]

Re: Mixing Stockholm Tar / Boat Soup

mrkgllsp,

Some of the old finishes seem to be making a comeback. Here is a nice explanation that might help - https://www.solventfreepaint.com/pine-tar.htm

I bumped into all this from saving an old steel boat. It was rusting from the inside out and all the modern finishes I found didn't help. An old shipwright led me to a linseed oil, pine tar product that was used by traditional cargo boats. Smelled nice and took a very long time to dry but stopped the rust and saved the boat.

The post and beam folk have a great respect for natural wood and finishes. I've been going to school on their work - https://www.heritagenaturalfinishes.com/Default.asp
They don't offer pine tar though

I find all this fascinating, who knew that finishes can smell good?

[David Satter]

Re: Mixing Stockholm Tar / Boat Soup

billy.jpg

[heimlaga]

Re: Mixing Stockholm Tar / Boat Soup

There are three reasons to use pine tar that I know of:
1. Pine tar is poisonous to fungi and it seeps into the wood filling out pores and makes the wood less susceptible to rot.
2. Pine tar is dark and provides a bit of UV protection.
3. Pine tar does not form a skin on the wood and therefore alows the wood to breathe.

Up here in softwood country where boats are traditionally built from spruce a boat that has been treated inside and out with some suitable mixture of pine tar and linseed oil and turpentine or ethanol generally last twice as long as a boat that has been painted or varnished.



Two time tested reciepies for boat soup:

Penetrating boat soup:
Pine tar, raw linseed oil, ethanol. The ethanol disolves the tar and makes it seep deep into the wood. The raw linseed oil also seeps in deep. There are any number of different proportions used. Some use lamp oil or even diesel fuel instead of ethanol though ethanol is way better in my oppinion.
I have found it best to mix ethanol into the pine tar until it runs like water. Then add raw linseed oil.

Boat soup that produces a good surface:
Pine tar, boiled linseed oil and turpentine. Between 1/2 and 1/3 pine tar and equal parts of the other two.

If the pine tar cannot be mixed it helps to heat it a little. If that doesn't help the tar is bad quality and should not be used.