bodywork joint seal going black

I wonder why manufacturers can't use a sealant which doesn't turn black or start going brittle.  I cleaned the roof on my Broadway a few weeks ago and noticed the sealant across the roof of the van, back and front, was black and was getting a crust on it that you could scrape off.  Only 3 years old, I wonder how long it will last before it starts to break up and leak?
Anyway, we sold the Broadway and bought an old Winnebago.
I cleaned the roof last week and was amazed to see white pliable sealant across the roof sealing the front and rear panels to the main roof.
No discolouration. No mould or black spots, no green algae, and all on a 17 year old vehicle.
There is also no visible sealant on the main bodywork to go mouldy.
If the Yanks can do it, why can't Autosleeper?

I know, it's a real pain and very unsightly. I have already had AS replace black and cracked areas of sealant on the roof of our Broadway roof at two years old!. Even round the windows the sealant is starting to crack. I added extra sealant to small suspect areas after only two months of purchasing our van from new. I regularly check our van sealant condition whenever I clean or wax the van. It is very time consuming, and I am fed up with it, I have better things to do, but it has to be done to try and prevent water ingress, which I have had experience with on previous caravans and a motorhome. Just recently been away to Spain and Portugal for 5 weeks. With all that rocking and rolling on their, sometimes very poor roads, it is time to check the sealant again!    B***** h***!!

Are you sure the sealant on your Winnebago hasn't recently been replaced prior to you buying it?

Pete

When we sold our Broadway, it had a damp check and passed 100%. No sign of damp whatsoever, so the sealant was still doing its job, although it was dirty.
The sealant on the new van seems original, certainly on the front and rear roof panels and hasn't been replaced in the 6 years the previous keeper owned it.

ajrm wrote:
If the Yanks can do it, why can't Autosleeper?

Good point.
We still use our 1984 Trophy Agrarian caravan we bought when 6 months old - all be it permanently sited in Derbyshire. The sealant on the seams on that is still pliable and flexible as if it were only applied recently.
So yes the stuff is (or was) available it's a pity we don't still use it.

ajrm wrote:Anyway, we sold the Broadway and bought an old Winnebago.

I think Motorhome Medics are involve with American RVs and parts. We use to use them for servicing of our Pollensa. They are based in Cheltenham. Might be useful ajrm.

My previous posting this morning said much the same, but strangely disappeared from this forum, and I know it went through. I did go slightly off topic, but surely not enough to be removed. I have had this issue before. Is there a glitch with the forum? Has anyone else come across this? Just wondered.

Pete

I've posted on threads before and not been able to find them next day.  don't know what happens...