Any spare Swedish pitch?

[graemefindlay]

Before I buy a box of pitch I wondered if anyone in/near Portsmouth has some leftover from previous projects/years?

 

[graemefindlay]

Before I buy a box of pitch I wondered if anyone in/near Portsmouth has some leftover from previous projects/years?

It’s me, hi, I’m the answer it’s me!

I’ve bought a box of pitch and I’m unlikely to use all 25kg so do shout if you have some pitch needs

 

[Roberto]

Is it the the same product called Stockholm/pine tar? I needed a small quantity I bought about half a kilo from Decathlon horseriding department, it's sometimes used on hooves. By the look/smell of it it's the same as boatbuilding tar.

 

[AntarcticPilot]

Is it the the same product called Stockholm/pine tar? I needed a small quantity I bought about half a kilo from Decathlon horseriding department, it's sometimes used on hooves. By the look/smell of it it's the same as boatbuilding tar.

Pitch is solid (almost; it flows very slowly over periods of years). Tar is gloopy (technical term ) liquid. I presume @graemefindlay wants to use it to fill seams or similar, in which case he will melt the pitch and pour it into the seam where it will set. Although both result from the destructive distillation of wood, they are taken off at different stages of the process.

55 years ago I worked for the Coal Tar Research Association, and the properties of pitch and tar were everyday matters.

 

[Roberto]

Pitch is solid (almost; it flows very slowly over periods of years). Tar is gloopy (technical term ) liquid. I presume @graemefindlay wants to use it to fill seams or similar, in which case he will melt the pitch and pour it into the seam where it will set. Although both result from the destructive distillation of wood, they are taken off at different stages of the process.

55 years ago I worked for the Coal Tar Research Association, and the properties of pitch and tar were everyday matters.

Thank you
Indeed I used it (tar) on a couple of wood pieces, on one I used a thin coat and it has dried in a few days, on another one I gave two coats and a few weeks later I am still waiting for it to dry completely, it's still sticky here and there.

 

[AntarcticPilot]

Thank you
Indeed I used it (tar) on a couple of wood pieces, on one I used a thin coat and it has dried in a few days, on another one I gave two coats and a few weeks later I am still waiting for it to dry completely, it's still sticky here and there.

Tar isn't a drying oil; it will become more viscous on exposure to air as lower molecular weight fractions evaporate preferentially but it doesn't polymerize and set like linseed oil does. I suspect that the one thin coat soaked into the wood, but the second coat couldn't and so remained on the surface. As the tar doesn't "set" it would remain sticky.

You can see this on the road. Freshly laid tarmac is quite sticky. After a while, the surface loses volatiles and absorbs dust, so it loses it's stickiness. But in hot weather it melts and becomes sticky.

Incidentally the chemistries of coal tar, bitumen and wood tar are all quite different, but their physical behaviour is very similar.

 

[graemefindlay]

Pitch is solid (almost; it flows very slowly over periods of years). Tar is gloopy (technical term ) liquid. I presume @graemefindlay wants to use it to fill seams or similar, in which case he will melt the pitch and pour it into the seam where it will set. Although both result from the destructive distillation of wood, they are taken off at different stages of the process.

55 years ago I worked for the Coal Tar Research Association, and the properties of pitch and tar were everyday matters.

Thanks for the technical details @AntarcticPilot. My plan is to use it to line a couple of keel bolt holes before driving new keel bolts in. I’m not sure if this is a good plan or a misguided one, but I’ll find out soon enough

As the proud owner of 25kg of the stuff I’ll be able to use it for many other things as well

 

[AntarcticPilot]

Thanks for the technical details @AntarcticPilot. My plan is to use it to line a couple of keel bolt holes before driving new keel bolts in. I’m not sure if this is a good plan or a misguided one, but I’ll find out soon enough

As the proud owner of 25kg of the stuff I’ll be able to use it for many other things as well

If I were you, I'd melt the pitch, pour it into the holes and then drive the keel bolts immediately. If you let it set, you'll have a devil of a job driving the bolts, and the pitch will fracture and not form a watertight seal. Pitch when set breaks like glass.

Perhaps a better procedure might be to melt the pitch, heat the bolts and dip them in the pitch before driving them. You could just put the boots in the pot with the pitch so they got to the same temperature. Drive them quickly so the pitch remains soft.

Incidentally, avoid breathing too much of the vapour from melted pitch. It's probably carcinogenic. I've been lucky; despite fairly extensive exposure to it in my late teens, I haven't had any problems so far! H&S wasn't a thing in those days, and I look back with horror on some of the things I did!

My one and only industrial injury (a scar on my little finger) came from working there!