Primer for ?trilux 33 on aluminium rudder

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Trevelyan

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Hi all,
The old international paint info leaflet I have says I should use etch primer +primocon + trilux 33, OR interprotect + trilux 33. International website doesn't appear to be marketing etch primer any more... will any etch primer do? Is the interprotect route better for some reason?

The rudder is a vertical lift/drop inside the stock, so there's a bit of rubbing when it is moved, if that's relevant.
Joys of new boat headaches...

Cheers!

Trev
 
Trevelyan said:
Hi all,
The old international paint info leaflet I have says I should use etch primer +primocon + trilux 33, OR interprotect + trilux 33. International website doesn't appear to be marketing etch primer any more... will any etch primer do? Is the interprotect route better for some reason?


Trev
Click to expand...

No mention of etch primer on the current datasheet for Trilux 33 . Interprotect or Primocon!
 
Personally I would always use etch primer on ali alloy, and in fact I did last year on a SD leg, followed by Primocon and Trilux.
Sourced from local car paint supplier.
You can get 1 part brush or aerosol or 2 part.
 
I'm now wondering If I should avoid trilux 33 as it contains some copper containing compounds, The surface of the anti foul and primer is likely to get chipped where the blade regularly contacts the metal frame of the stock. I wonder if this will lead to galvanic corrosion in these chipped spots. Any thoughts? This appears to be where the previous anti-foul coat failed. Trev
 
JumbleDuck said:
And, just to complete, Primocon is fine to go on aluminium.

http://www.yachtpaint.com/MPYACMDatasheets/Primocon+eng+A4+Y+20141215.pdf
Click to expand...

That data sheet says this:

ALUMINIUM Degrease with solvent or Super Cleaner. Sand well using 24-120 grade (aluminium compatible) paper.Coarser grades are recommended to achieve optimum adhesion. Clean thoroughly and allow to dry. Pre-prime using anInternational primer as soon as possible (within 8 hours) as detailed for specific coating systems.

which I find quite confusing. Pre-prime before the primer using a primer?
 
alahol2 said:
I don't think it does. It's specifically stated as OK for use on aluminium.
Click to expand...

There is no mention of copper compounds as such in the current safety documentation but I am pretty sure at one time it was stated to contain cuprous thiocyanate!

Now hidden under heading "Metal salts of thiocyanic acid" perhaps ??????

Whatever, it is sold as suitable for use on aluminium!
 
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Interestingly in the pre-prime with a suitable primer, they don't say what. If they intend you use something like inter-protect (epoxy-based) are they relying on it being intact!

I think cuprous thiocynate (excuse spelling) is in there....

I also have an outboard leg to do so am very keen to get this right!
 
The datasheet for TRILUX advises uses PRIMOCON for aluminium.If the aluminium is new and anodised you do not need to etch it since anodising provides a good key.If the alumium is aged then you also won't need to etch it.
 
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Well spotted VicS and thanks very much for your effort. I only looked at the datasheet on the manufacturer's website, which appears to only imply Zinc compound content:
http://www.seajetpaint.com/en/products/antifouling/seajet-034-emperor/ (link at bottom of list)

I wonder however if the zinc content of the paint is there to keep the copper content under control (i.e. give something sacrificial, rather than my aluminium!!)
The seajet data sheet (as per link above) is very explicit about 'no risk of galvanic corrosion'.

I am yet to find an antifoul without any copper compounds. I wonder if I should just paint the top surface of the rudder (boat is on a drying mooring in a fairly low fouling area anyway)...

Trev
 
Trevelyan said:
Well spotted VicS and thanks very much for your effort. I only looked at the datasheet on the manufacturer's website, which appears to only imply Zinc compound content:
http://www.seajetpaint.com/en/products/antifouling/seajet-034-emperor/ (link at bottom of list)

I wonder however if the zinc content of the paint is there to keep the copper content under control (i.e. give something sacrificial, rather than my aluminium!!)
The seajet data sheet (as per link above) is very explicit about 'no risk of galvanic corrosion'.

I am yet to find an antifoul without any copper compounds. I wonder if I should just paint the top surface of the rudder (boat is on a drying mooring in a fairly low fouling area anyway)...

Trev
Click to expand...

they say its suitable for aluminum. The priming coat may be all important or maybe copper(I) thiocyanate does not pose the same risk as copper(I) oxide

The zinc content is mostly zinc oxide which AFAIK is simply a pigment and a little zinc pyrithione which I believe is a biocide.

i was wondering why you need to antifoul a lifting rudder. Don't or can't you simply lift it clear of the water?
 
It doesn't entirely leave the water (plus boat on drying mooring). Yes I had wondered if I could just get away with painting it...!! Trev
 
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