Sealer on before primer? Got significant blistering in gelcoat. Easy questions.

[Darren Nemeth]

I read past threads and youtube videos on crazing and blistering and know what I am getting myself into BUT have some basic questions I can't find answers to.

1) The pix is of my hull. All the Batboat latex paint is stripped off and I am ready to start sanding the gelcoat with 80 and 220 grit. Inside the yellow lines is where the majority of the blistering is (same areas where soggy, waterlogged foam was inside). Crazing and blistering is really bad near the stern.

Most of the delamination is visible but how do I get all of the hidden blisters to reveal themselves? Will my sanding the gelcoat with 80 and 220 grit pop them out or is there another more efficient technique? Or it is better to remove all gelcoat in those areas down to glass?

2) Here and on youtube I found mentions of applying a "sealer" on the gelcoat before primer but nothing specific.

Please elaborate.

Will be using 3 sanded coats of Easypoxy White Undercoater as primer. Is that it?

Thanks in advance.

 

[Shife]

Re: Sealer on before primer? Got significant blistering in gelcoat. Easy questions.

This link contains all the info you will ever need to know to fix this problem properly:

http://209.20.76.247/ss/assets/howto-pub2/Gelcoat Blisters Diagnosis Repair and Prevention.pdf

Don't get the contents of the blisters in your eyes! Seriously bad nasty stuff.


If it was me I would use either a GelPlane (preferred) or a Festool planer and peel the gel coat and part of the first layer of laminate off. Tent and dry the laminate for at least 6 months. Then skin the laminate with a layer of 7 to 10 oz cloth and epoxy. Skin that with two layers of neat epoxy. Then start building up a fairing coat of VC Tar or Interprotect. Sand that to fair and cover with an appropriate hard ablative anti-fouling such as VC17, SR21, or Vivid.

 

[drewpster]

Re: Sealer on before primer? Got significant blistering in gelcoat. Easy questions.

Ever found a gelplane for less than than the kids college fund to buy? Good luck. It would be nice if there was somewhere to rent one.

 

[Shife]

Re: Sealer on before primer? Got significant blistering in gelcoat. Easy questions.

Pretty sure you can pick up a new GelPlane for $2k. Certainly not cheap, but look into hiring the job and it will look like a bargain. A Festool planer will be cheaper but the results will not be as good. I guess the value is subjective to how much you like to sand and fair.

 

[ghamby]

Re: Sealer on before primer? Got significant blistering in gelcoat. Easy questions.

I had to repair a blister problem on a '68 Sailmaster. Lots of half dollar sized
blistersand crazed gelcoat. I sandblasted the bottom and cut or ground out
the blisters. Fared out the whole mess with epoxy and painted with barrier coat.
A sand blaster you can rent. GH