graemefindlay
New member
Before I buy a box of pitch I wondered if anyone in/near Portsmouth has some leftover from previous projects/years?
Any spare Swedish pitch?
- Thread starter graemefindlay
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graemefindlay
New member
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
Well-known member
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
Well-known member
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
Well-known member
Thank youPitch is solid (almost; it flows very slowly over periods of years). Tar is gloopy (technical term
55 years ago I worked for the Coal Tar Research Association, and the properties of pitch and tar were everyday matters.
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
Well-known member
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.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.
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.
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