Epoxy types, price/quality

[Tiboo]

End of this month I'm going to DIY paint my hull; I decided to go for epoxy. I've found already some valuable info here and elsewhere (I know I have to strip off the blacking to bare metal). As I've a few (related) questions, I've organised it a bit, so you can refer to the numbering if you want!:

 

1. So, first of all, I was wondering what is known about the quality (&price) between different types and brands of epoxy. Some brands I found so far are Sigmacover 300, Jotamastic 87, Hempadur (45143/45141), Interzone 954. (Are there any other important ones to take into account?)

 

2. I'm further curious if anyone has advice about these particular treatments I found in the forum: 
a) coal tar epoxies ("for off shore splashzone use")
b) epoxy over zinga (http://www.zinga-uk.com) 
c) vinyl blacking (Leighs Resistex M535)

 

3. I also have a few other related questions:
a) Are all epoxy-paints self-priming?
b) How many coats should (better) be applied? There seems to be consensus on 4..?
c) What about the base plate, I suppose it should be simply included in the job, right? It seems some people don't...
d) What's the best way to deal with rust? Scaling down to bare steel and painting over, or applying rust converter fist?
e) Are metal putties advised or to be avoided?

 

Thanks!

~

K

[Alan de Enfield]

11 hours ago, Njiruk said:

d) What's the best way to deal with rust? Scaling down to bare steel and painting over, or applying rust converter fist?

My (limited) understanding is that the Hull must be grit-blasted to remove all traces of rust and old paint/blacking and the epoxy applied immediately afterwards before the metal starts to get any 'damp-air' on it.

[Bee]

I would avoid anything that says 'coal tar' in it, this is becoming phased out due to environmental issues and overcoating it in the future might be awkward. Jotun do a 'Surface Tolerant 'epoxy, Can't remember the number of it, I hope its good as I used it last year over some Sigma stuff with coal tar in it (since discontinued) Base plate?  Yes, makes it expensive but bare steel underwater? It will rust. I think that the answer (if there is one) to corrosion is really down to keeping the paint on. Epoxy is probably best but if if faced with a huge bill for grit blasting and epoxy paint there could be a case for bitumen and annual docking?

[Boater Sam]

Could I suggest you ask the number 1 company in the world for marine coatings? Sherwin Williams of Bolton, was Leighs Paints.

 

https://www.coatings.org.uk/directory/sherwin-williams-protective-marine-coatings_1414.aspx?DirectorySearchPageId=1

 

I did, 20 years ago. The recommended 2 coats of epoxy zinc onto bare steel and 2 coats of epoxy black, can't remember the name.

It has done me well.

 

I hand scraped my hull with a Skarsten hand scraper and painted it, none has fallen off yet, The only rusting is where we have ripped it off on concrete. Its been out 3 times in 20 years just to be touched up, washed off and 1 coat of black.

 

I was surprised how cheap the proper epoxy was from the makers compared with the trade named stuff.

 

 

[Stevec]

ref " vinyl blacking (Leighs Resistex M535) " We used this for the last 20+ years on our boat. I worked for Claymoore narrowbaots and was introduced to this paint by them. Extremely good. You have to scrape off the bitumen before coating with resistex. Our first coating bubbled with the bitumen residue but after 2 coats it was OK. We have had no further pitting or rust/ galvanic activity and the sides are still perfect. It drys extremely fast (uses very volatile thinners) - two of you can apply coats with one only about 3 metres behind the other and when finished theres no curing time - just flood the dock and sail away.

[Bee]

Sherwin Williams paint has just been used on the Iron Bridge in Shropshire, I'm going down there in a minute to walk the dog and get the Sunday papers, It looked good yesterday and I expect it will still be OK today. Must be good stuff if English Heritage used it.

[Tiboo]

Ah, now I find this fairly related thread on 2 pack recommendations: https://www.canalworld.net/forums/index.php?/topic/95819-which-2-pack-for-blacking/
Coal tar still seems to be for sale, but it might be worrying indeed if it’s not compatible for overcoating later + I might want to take my ecological responsibility, if it’s a serious concern…
I’ll call that Sherwin Williams  tomorrow! & thanks for the Skarsten tip, I like those zen kind of jobs ? I also got myself a Tercoo, I’ve heard a few people highly recommending that to remove Bitumen.
So, it will take me more time than grit blasting indeed, which might become problematic regarding the quick rust formation once the bare metal is exposed to the air.  I was thinking, since it’s just a thin layer, could it not be easily and quickly sanded away just before applying the primer coat?

[Boater Sam]

Trying to sand bitumen is like pushing water uphill.