Epoxy Impregnation When to do it and when not?

In Sheet 05 François Vivier explains that Impregnation it's highly recommended: For all parts of plywood, particularly "okoume,"...
Q1: Should we impregnate everything including the Strakes?
Q2: How many hands do we give them?
Q3 Sanding between hands, Can be avoided?
Q4: If we impregnate the strakes, do we run the risk of having a deficient two-step bonding?

Hi Sebastian.
This is a topic which has vexed many builders, not only within the Morbic fraternity, and exposed varying opinions.
See here https://forum.mymorbic.uk/Why-mask-the-gluing-surfaces-td428.html for some discussion and links to other resources and opinions.
Hopefully other forum members will add their views.
Paul W

Hi, I asked Ms. Vivier if an epoxy coat is recommended over the entire hull and his advise was the following:


I am not fully convinced about the West Systel theory of encapsulation with several layers of epoxy. It was certainly a very interesting approach when they developed this system, but today we have other existing products.
If you intend to varnish the hull planking or other parts of the boat, applying epoxy resin is still a good way before the application of varnish. However, I will limit the number of coats of epoxy. The aim is to wet the wood with the resin but not to get a thick and hard surface which needs a difficult sanding before applying varnish. The resin may be applied with a squeegee instead of a brush. My best choice for varnish is Epifanes rapid-clear, about 8 layers followed by a last coat of Epifanes clear varnish.
If you intend to paint, epoxy is not required, except for the edges of the plywood parts and the end grain of timber parts. When the boat is assembled, you may coat it with a two parts epoxy primer. This product is very different from epoxy resin. It looks like paint (generally white or grey). It is thick to cover all surface defects and easy to sand, which is not at all the case with epoxy resin. Then you may apply the finishing paint of your choice.

Hope this is useful for you.

Best regards,
Carlos Herrán

Gracias Carlos,
I appreciate you sharing this information, it is very useful. I understand that the best alternative would be the epoxy primer when applying paint.
Thanks !!

Hi Sebastian, following Ms. Vivier advise I didn’t impregnated the strakes with epoxy. I applied 3 coats of epifanes epoxy primer and 2 coats of epifanes poly urethane yatch coating and it looks very solid, it makes a nice  film from the first coat, and although I can not talk from experience I certainly expect it to stand up well. For the brightwork I applied 7 coats of epifanes rapidclear and the end result looks very good although obviously not as strong as the paint system. One thing that has bothered me a little bit is that when I applied the first coat of varnish on the iroko thwarts it took a long time to cure, more than expected from the technical specification expected time of 6 hours, probably around 3 or 4 days.

Best regards,
Carlos Herrán