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S&S Swan Maintenance - Blisters in the top sides?
06 August 2016 - 08:20
Join Date: 03 March 2007
Posts: 241

Blisters in the top sides?

Dear all,

in 1999 I refinished the hull due to spider cracking. She had been in the open in Maryland for 18 years and the UV light had played havoc with the gelcoat. She was faired and repainted with awl craft which is still in good shape after ..... Hard to believe 17 years. Last spring while preparing her for our crossing I found a few small blisters on the topsides. This year more arrived. I have opened up a few and there is nothing in them just air....very odd. Anyway, I am in the process of sanding them out and repainting but as I am unsure of the cause I am doing a temporary job with International Perfection 2 part ( the whole hull). I will then wait a couple of years to see if more blisters appear before getting her professionally painted again. I have considered pollen trapped between the Awlcraft and the gel coat... A bit weird that it takes so long to react... Moisture coming through the hull from inside... But as it is on both sides and not in any consistent area I am at a loss. Any thoughts as to the cause? I like to know why things happen rather than just repairing.....


Thanks in advance


Mike from Storm Svale


S&S Swan 40 

07 August 2016 - 10:58
Join Date: 02 January 2008
Posts: 1547

Dear Mike

You mention fairing and repainting long ago.
It is known that improper mixing of two-component paint can cause topside blisters, but in your case the delivery time is extremely long.
If no other reason can be found it would be advisable to remove the topcoat and primer layers entirely, and redo the paint job.
Kind regards

08 August 2016 - 14:15
Join Date: 03 March 2007
Posts: 241

Thanks Lars!!  

I still have no idea what caused this!!  If I need to remove the paint and filler I may as well remove the original Gelcoat which is spider cracked... back to where I was in 1999.  Rats!!!  Hopefully there are some more ideas out there as to the cause of the problem!

All the best





18 August 2016 - 07:48
Join Date: 03 March 2007
Posts: 241

Dear Lars,

I spent the last two days sanding the topsides.  The bubbling was in the Awlcraft.  Very few of the blisters got to the Gelcoat but not into it.  I have sanded them all out and in general they simply disappeared when lightly sanded as they were superficial.  She had two coats of Awlcraft put on orginally as I was not happy with the first coat.  Seems like the flaw is in the second coat. Some thoughts.  She was painted in the US in the fall outdoors and has been in cold weather climates up until 2013 and 2014 when she was in the Caribean and then in the Cheasapeake, both very hot. The blistering did not start until then. So I am wondering if it was incorrect mixing as you suggest, but that it did not appear until she was in the hot climate. Heat plus poor mixing equals blisters is my working hypothesis at the moment.  I will paint this weekend and see if they come back. If they do it will be a total strip as you suggest.  I am going to contact International to see what they say about this.


So I think you are right with the improper mixing!!! but in the second coat only. 


Thanks again!!!!! 






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