I came up with another way to separate a stuck mast.
I got 4 hose clampls from Bunnings: two 33-57mm to fit around the mast and two 17-32mm.
I've put the smaller clamps around the side of each of the larger ones.
Then put the large clamps on the mast to each side of the joint point. I left enough space between the clamps because I didn't want to clamp down on the ferrule. I used rubber mats as a padding between the clamps and the mast, and then tightened the clamps as much as I could.
Then I stuck the car jack between the clamps and slowly started jacking up. The smaller clamps' rings provide support for the jack.
After a while I heard a cracking noise but no effect. I released the jack, loosened the clamps and rotated them on the other side of the mast. Then I jacked up again.
After a few minutes of that the mast finally started to come a part, and I finally had it in 2 pieces again!
I discovered that was one of the clamps sliding down the mast. I didn't tighten it enough, it pierced through the padding and scratched the mast.
I put a thin coat of dishwashing liquid on my mast join and extension. It. Still grips hard but comes apart a lot easier
Naaaa, using that will damage the mast. Do some stress maths on it.
Good luck anyway
Coincidentally, I gave my mate a hand to separate a stuck mast. We tried twisting, we tried boom twist. All to no avail ! Finally, we griped the mast with the boom, lined up the wishbone of the boom accurately on a solid wooden post, and then 2 of us tugged / jerked hard on the mast. By the way, we also had a third person to ensure the wishbone does indeed catch on the wooden post.
Miraculously, 2 tugs and it was separated.
Select to expand quoteqldnacra said..
An even better way to seperate a mast without using a car jack
...and wipe the joints with a clothe after each session. The black stuff on the rag is what builds up and causes the pieces to stick.
One very simple solution to avoid a stuck mast. When you are done with the mast, roll up a plastic shopping bag and stuff it inside the base of the mast. Of course you want to make sure it doesn't go in too far.
With it in place, you will not have to worry about having sand/grits at the base. If you can find a cap of some sort to fit the mast, then it is even better. Don't forget to remove the bag before rigging though 
I fill my mast with expanding foam. It takes about 4 cans and adds about 3kg to the rig, changed the bend but it stops sand and grit getting in and the mast never gets stuck together. It's worth the reduction in performance
I fill the mast with lead ,stops sand getting in , bitch to water start , what do u know about lead , hard to say , but if u get it for half the price ! , sorry I've been drinking !
Select to expand quoteImax said..
I fill the mast with lead ,stops sand getting in , bitch to water start , what do u know about lead , hard to say , but if u get it for half the price ! , sorry I've been drinking !
Smooths out the chop, and carries momentum through carve gybes.
try putting a condom on the side without the ferrule
best to leave it on during action
that way there are no unwanted surprises 
for real action put it on your ferrule
this idea was not influenced by alcohol
just my insanity
Personally, I solved the problem of sand and grit getting in by aralditing the two halves of the mast together.
It also lasts longer than tape.
A way that has woked for me is tie rope with clove hitches and rolling hitches to the mast. Tie the base end to something really strong like a bollard or parked truck. Tie the tip to a rope and first jerk on it. If you need more grunt, tie the tip rope to something heavy like a lump of steel say 20 kg, give that a good jerk. If you need more grunt still, have about 1 or 2m of slack rope and hook it on your towball. Gentle pull first, if you need more grunt, have a run up. Pulled a 12m long mast off a mould like this so it can definitely separate things. Stiff rope like kevlar or at least pre stretched poly is best. One of my mates glassed some loops on the end of a stuck mast to tie to, then sanded the loops off when separated. But enough hitches usually does the trick.
i spose you could put hose clamps over rubber, then tie a clove hitch around the mast resting against hose clamp.
Or you can just water the grass where you rig up.
That's a pretty scary way to do it, too much stress on one side of the mast.
I prefer the two booms method, twisting in opposite directions, much safer and your mast won't hate you.
Always found 'bouncing' the mast vigorously while a couple people pull on each end to be the most effective and least risky way to do it.
Select to expand quotePiv said..
A way that has woked for me is tie rope with clove hitches and rolling hitches to the mast. Tie the base end to something really strong like a bollard or parked truck. Tie the tip to a rope and first jerk on it. If you need more grunt, tie the tip rope to something heavy like a lump of steel say 20 kg, give that a good jerk. If you need more grunt still, have about 1 or 2m of slack rope and hook it on your towball. Gentle pull first, if you need more grunt, have a run up. Pulled a 12m long mast off a mould like this so it can definitely separate things. Stiff rope like kevlar or at least pre stretched poly is best. One of my mates glassed some loops on the end of a stuck mast to tie to, then sanded the loops off when separated. But enough hitches usually does the trick.
i spose you could put hose clamps over rubber, then tie a clove hitch around the mast resting against hose clamp.
Or you can just water the grass where you rig up.
Icicle hitch
Select to expand quoteMan0verBoard said..
What do you reckon the 'crack' sound was?
Gonna find out next time it's rigged.
Someone somewhere showed how to connect a hose and fill with water thus pushing it apart.
