Tried to reply to an old post on this topic but could not, so posting as a new topic.
My 490 cm Epic Gear 100% carbon mast got stuck together after a session in crashing waves. Searched on how to seperate and mixed and matched to come up with a one person mast safe solution.
Soaked inverted joint with WD40 and left O/N inverted/standing upright. Then tied a hitch knot to lower section just below joint, wrapped rope around tree, and tied second hitch knot to lower section. Then boiled a quart of water and put in a thermos, slowly poured hot water on female side of joint so water wrapped around section for 20-30 seconds, then twisted upper section to take up rope slack, and then twisted hard for a second at most and mast seperated with no damage. Carbon fiber is cured at around 100 degrees C.
Three or four strong blokes on either section twisting opposites ways - it will come off.
In a sandy environment, the best action is to prevent sand from getting in there in the first place.
Wrap the joint with tape. 1. This keep the sand out. AND 2. it keeps the mast from gapping during rigging.
Select to expand quoteBasher said..tonyk said..
www.seabreeze.com.au/forums/Windsurfing/General/How-to-separate-stuck-mast-using-car-jack?page=1
Don't do this.
You'll **** up an expensive mast.
A boom on each side of the join; both v tight. It works :-)
Like many of you, I have helped several people separate mast sections after a windsurf session. I'm not saying I'm an expert on this but I have made several repeat observations.
1) The mast jams because sandy or silted water has got inside and the water escapes but the sand or grit is left behind.
2) Because of 1) its a good idea to check all your mast bungs and the mast tip are in place, because that's where the water usually gets in.
3) If you can be bothered to tape the joint each time you sail then this is a good idea, but it won't work if the mast bungs are not in place. (See above). I don't tape my own mast joint.
4) Your first reaction is to attempt to twist the mast apart, often with the help of others. This usually works, BUT if the mast joint rotates but the two sections stay together then, ooops, that's a sign that one big bit of grit is inside and when rotated it scores a groove into both sections of the joint. That grit then holds the joint together and you've made the situation worse...
5) Masts are fragile, and the expensive ones even more so. Do not use mechanical means to separate an expensive 100% carbon mast. No winches or car jacks. No attaching one end to a fence and the other to your car which you then drive away. These are blokey things to do, and you'll feel better in applying a macho solution - but it'll usually ends in tears. In particular, the problem usually comes when you attach some rope or webbing which crushes the mast sections, a crush load mast top sections are not made to take. When separating a mast with the help of others, watch out when an Alpha male tries to take over.
6) Applying a boom on each section does allow relatively few people to gently rotate the mast sections at the joint. If they pull from each end, then the mast should come apart straight away. If it doesn't then a bit of stubborn grit will quickly make the issue worse. See point 4).
7) Take out the mast tip bung (in the top section) and get a water hose inside the mast to rinse out the sand. Shake the mast from one end in a whippy motion, and repeat the water treatment - as that's how the sand got in the joint in the first place and reversing the process with water from a hose can release the joint.
8) Another solution which can work is where you place a bag of ice on the 'male' section and wrap a hot towel over the 'female' section - using hot kettle water - the obvious aim being to shrink the spigot whilst widening the hole.
9) In bad cases, remember that a mast can cost a lot of money and there is no rush in trying to separate it. In my experience, most people have ****ed up their mast before they try the hose solution.
10) Avoid all these problems by reading points 1) and 2) again.
Plug the bottom of the mast with a spud so it seals tight then using a compressor blow gun stick the end in the mast tip and the pressure should pop the mast apart, never tried it but there always a first.
Tape your mast, isn't the choice of the coolest dudes on here but would prevent these threads every few months.
Here's the steps:
1. Buy electrical tape available from any supermarket or hardware store
2. Wrap tape around the join when rigging
3. Done.
4. Enjoy hassle free separation of mast at the end of session.
Note: Re: Step 3 and 4, no effort required.
for me the stuck mast has always been because the bung or end cap isn't sealed properly as basher has said.
recently the guys at the beach showed me 2 new ways of separating masts.
first method.
hold the mast vertically with the tip on the ground and just shake it for a few minutes.
the wobbling crushes the sand in the ferrule.
second method.
hold the mast at the tip with the bottom end up in the air. like a pole vaulter. then let the bottom end drop and hit the grass while holding the tip.
this wobbles the ferrule and crushes the sand.
Select to expand quoteGestalt said..
for me the stuck mast has always been because the bung or end cap isn't sealed properly as basher has said.
oh sh## hey, Here I was thinking it was due to sand getting inside the join. I guess you learn something new every day 
What if you taped the bung as well?
I have never taped my masts. and never had one stick. until the bungs come loose. then they get stuck every time and continue to stick until i wash them out and redo the bungs.
i reckon sand fits through an extension easier than a ferrule joined under load. i mean which one has the 6mm holes in it.
Select to expand quoteolskool said..
Don't leave sails lying in the wash zone at edge of water. = No stuck mast.
Yep , that's the only time I gots a stuck mast.
Select to expand quoteslowpoke2 said..
Just go retro and tell everyone it's a one piece
They would be better masts, and lighter!
Select to expand quoteduzzi said..slowpoke2 said..
Just go retro and tell everyone it's a one piece
They would be better masts, and lighter!
it's true they would be lighter. way back in the 90's my first carbon masts were one piece No Limitz from KA sails Australia.
they were super light and quite durable. Not long later I got a 2 piece version of the same mast and it was about 200gm heavier. It is purely in the ferrule and reinforcing for the join.
I cant say I ever noticed any performance difference in the way the sails set. I sure there would be some effect on the bend curve, but I suspect it is so small as to be very hard to notice.
At the time there was a rumour that in Europe, people were not allowed to transport one peice masts on their cars roof racks (too long) which is what brought about the change to 2 piece masts. I am sure that all of us now greatly appreciate it anyhow. 
Select to expand quoteGestalt said..
I have never taped my masts. and never had one stick. until the bungs come loose. then they get stuck every time and continue to stick until i wash them out and redo the bungs.
i reckon sand fits through an extension easier than a ferrule joined under load. i mean which one has the 6mm holes in it.
Agree as my 460 was getting stuck and no bung. I had a small can of expanding foam I was going to use, spray then plastic bag over and and turn upside down. Of course the can had been sitting around for too long 
I used silicone 
I still have a one piece Kiwell 430 that I use
