Mild steel...paint before epoxy?

[Iain C]

My stbd capshroud goes thorugh my deck and the chainplate bolts to a dodgy looking wooden shelf thing in my heads. Looks like it was laminated by Stevie Wonder after a trip to Halfords to stock up on fibreglass.

I have ripped it all out (literally, ripped it with hand tools...) and I am substantially beefing it up. I am also going to bolt the chainplate to a piece of angle, welded to a chunky piece of bar which runs across the heads from bulkhead to bulkhead, with flat bar welded on the ends to spread the loads across the bulkheads which it will be bolted to. For reasons of cost and easy working/welding, the steel is all mild steel rather than stainless, and it will be thouroughly glassed in as part of the final structure with no exposed area at all.

Question, is it better to paint it first with Hammerite or similar, or will I get better corrosion resistance (as well as a stronger bond) if I just epoxy it straight in without paint?

It's in a totally dry area of the boat by the way.

 

[PCUK]

Clean off all mill scale with a grinder and coat with epoxy primer. Then glass in.

 

[oldsaltoz]

I would be inclined to use some rust remover/preventer then a primer, then epoxy.

Good luck.

 

[CreakyDecks]

I always think "glassing in" looks horrible. Make a feature of it and have it blasted and powder coated

 

[Iain C]

Cheers guys. Any recommendations for epoxy primer?

CreakyDecks...so do I. So all of it will be hidden away behind the existing wooden trim of the heads locker. I'm using weave, not CSM too.

And if it was'nt hidden away, the last layer of glass would have been carbon...just the thing in a 1970s cruiser!!

 

[TQA]

Why not get it galvanized ?

If you want to paint it get it bead blasted then paint with zinc rich epoxy say 4 coats with the first coat going on within minutes of the blasting.

 

[ianj99]

Cheers guys. Any recommendations for epoxy primer?

CreakyDecks...so do I. So all of it will be hidden away behind the existing wooden trim of the heads locker. I'm using weave, not CSM too.

And if it was'nt hidden away, the last layer of glass would have been carbon...just the thing in a 1970s cruiser!!

Use Epoxy Mastic from http://rust.co.uk

You can also pretreat it with their FE123 rust converter, this is excellent.

I use both on my steel ketch and it is very good, mix ratio not critical, sets down to at least 5c, doesn't run or sag, is easy to sand or rub down and remains slightly flexible and is well priced.
So perfect for boats as well as its main use in vehicle restoration and preservation.

 

[Conachair]

If you want to paint it get it bead blasted then paint with zinc rich epoxy say 4 coats with the first coat going on within minutes of the blasting.

Whatever course you take it would be a very good idea to blast to get rid of the mill scale from the steel before any kind of coating.

Check out what mr google says - http://lmgtfy.com/?q=mill+scale+corrosion

 

[PCUK]

On small items grinding is perfectly feasible and just as effective as blasting.

 

[TQA]

On small items grinding is perfectly feasible and just as effective as blasting.

Sorry but this is not the case, esp. if there is any rust or millscale present.

As the OP is planning to glass the component in, the part must be protected as well as it can be.

 

[SAMYL]

POR 15 seems to be the stuff to use these days.
Available from Frost Engineering or Eastwoods. (or Ebay).

 

[Iain C]

Thanks for the input guys. Re the grinding/blasting thing, the steel at the moment is totally rust free (it actually seems to have had a slightly oily coating on it). I was planning on using one of those flexible sanding discs on my angle grinder, which gets steel to a very bright finish indeed.

Will this do it?

 

[rib]

25 yrs stove enamelling business ! watch your welds and inside edges on holes if your gonna use mild steel only