Primer for Stainless rudder

FrankJB

FrankJB

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I made this nice shiny new stainless steel rudder and skeg for my LM27
New_rudder.jpg


Painted it with with some Blakes underwater primer I had kicking around and then antifouled it.

When the boat was lifted out at the end of the season the hull was nice and clean but the rudder, prop and anode looked like an exhibit from the Sea Life centre!

Rudder_4.jpg


Anybody got any good advice about the treatment of stainless steel under-water?
 
I have a stainless rudder on my Colvic Watson motorsailor
Coated it with gel coat x 2, then 2 x primacon, 2 x antifoul
Wears the same as the hull.
Hope this helps
Mike
 
Trade secrets here

Stainless like copper theoretically can not be painted to a finish that lasts for a reasonable ammount of time in any product so that a paint manufacturer can sell a product that is guaranteed on any of these substrates.

However if you do choose to paint stainless, the best way to do so is as follows, (as you quite rightly point out that the primer has given way)

Assuming you are starting with bare stainless,

Abrade the stainless with a grinder and an 80 grit grinder disc to form a key.

wash any contaminants off with a de-greaser, a few applications are usually required, wash on and wipe off with clean lint free cloths.

Heat the stainless with a hot air gun so as that it is warm but not so hot that it starts discolouring or buckling out of shape.

This will enable the pores in the steel to expand allowing the first coat of slightly thinned out epoxy (2 part) primer (approx 15%-20% thinned) to soak in. Check data sheets for the primer that it can withstand high temperatures, as well as having a high flash point (as most epoxy primers do)

When the steel cools and the pores of the steel contract they will allow a bond between the primer and hte steel. Although this is not a perfect bond it is the best way to get a bond outside of a coatings factory.

When the primer is tacked off, ie when you touch it the paint does not stick to your finger but leaves a slight impression, (5-10 mins) depending on primer manufacturer, apply by brush or spray a second coat of primer.

This second coat, allows a sufficient product build so that the first coat grips in but the second coat acts as a barrier or protection.

Just after the second primer coat tacks off, apply 1 coat of antifoul. This creates a chemical bond between the antifoul and primer. If this is not done, theoretically the antifoul can peel off sooner than expected and the primer will be eroded by the marine environment.

You can now follow the antifoul manufacturers application recomendations for further antifoul coating. However 3-4 coats at 30-90 min intervals on a warm dry day would be good.
 
No noticable loss of power under engine (but it is 35 HP) and nothing very noticable under sail. I put this down to the hull staying so clean, I have to say the rudder did feel a bit "different"!

Frank
 
[ QUOTE ]
Very impressive mini sea-life centre you had there!

Was there any noticeable loss of propulsive efficiency with that bearded propeller?

[/ QUOTE ]

No noticable loss of power under engine (but it is 35 HP) and nothing very noticable under sail. I put this down to the hull staying so clean, I have to say the rudder did feel a bit "different"!

Frank
 
Many thanks for the excellent advice form both caerurfa8803 and alienzdive. I think I have learned a good lesson about using up those old tins of paint I've had around for years. Something about 'spoiling the ship for a ha'peth of tar'.

Very many thanks

Frank
 
[ QUOTE ]
Trade secrets here

Stainless like copper theoretically can not be painted to a finish that lasts for a reasonable ammount of time in any product so that a paint manufacturer can sell a product that is guaranteed on any of these substrates.

[/ QUOTE ]Funny that, Stainless steel is painted on occassions for use in "marine environments" and the coatings do last - up to 25 years or more
[ QUOTE ]
However if you do choose to paint stainless, the best way to do so is as follows, (as you quite rightly point out that the primer has given way)

Assuming you are starting with bare stainless,

Abrade the stainless with a grinder and an 80 grit grinder disc to form a key.

wash any contaminants off with a de-greaser, a few applications are usually required, wash on and wipe off with clean lint free cloths.

Heat the stainless with a hot air gun so as that it is warm but not so hot that it starts discolouring or buckling out of shape.

This will enable the pores in the steel to expand allowing the first coat of slightly thinned out epoxy (2 part) primer (approx 15%-20% thinned) to soak in. Check data sheets for the primer that it can withstand high temperatures, as well as having a high flash point (as most epoxy primers do)

[/ QUOTE ]Pores in stainless steel? if you have then scrap the material. Commercially available Stainless Steel is not porous.
[ QUOTE ]
When the steel cools and the pores of the steel contract they will allow a bond between the primer and hte steel. Although this is not a perfect bond it is the best way to get a bond outside of a coatings factory.

[/ QUOTE ]Says who? - I have never read such nonsense about painting/coating in my life. Are you actually just taking the pi$$ or do you really believe such rubbish?
[ QUOTE ]
When the primer is tacked off, ie when you touch it the paint does not stick to your finger but leaves a slight impression, (5-10 mins) depending on primer manufacturer, apply by brush or spray a second coat of primer.

This second coat, allows a sufficient product build so that the first coat grips in but the second coat acts as a barrier or protection.

[/ QUOTE ] And traps solvents etc and inhibits the proper curing of the prime coat resulting in a poor. low strength base coat thich would be prone to failure.
[ QUOTE ]
Just after the second primer coat tacks off, apply 1 coat of antifoul. This creates a chemical bond between the antifoul and primer. If this is not done, theoretically the antifoul can peel off sooner than expected and the primer will be eroded by the marine environment.

You can now follow the antifoul manufacturers application recomendations for further antifoul coating. However 3-4 coats at 30-90 min intervals on a warm dry day would be good.

[/ QUOTE ]
I trust you do not apply antifoul or any other paint system "professionally".
--------------------
hammer.thumb.gif
"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
 
I agree with you Cliff, I hope he never paints any boat I have anything to do with.

For the original poster, surface should be lightly blasted (in preference to grinding, and never sanded), epoxy (zinc free) primed/build coats and antifouled to the paint manufacturer's data sheets as if for steel (which for the antifouling MAY or MAY NOT advise applying while epoxy paint under not fully cured - depends on the antifouling - is not a rule as another poster has claimed).

If the original poster finds the 100% cure for the prop fouling, rather than marina myths, then let us all know /forums/images/graemlins/smile.gif.

John
 
I am also with Cliff and ship_cat
Stainless steel should be treated like any other steel.
Grit blast
paint with epoxy asap (within 4 hours)

I put 3 coats epoxy priner /undercoat then 3 coats of epoxy tar with in 48 hrs or previous coat. then sand to key and paint antifouling just before launch.

Do a search on forum to painting steel lots of info in last month or 2.
 
I would leave the stainless without paint. Look at the clean bottom ! This stainless rudder seems to be stealth antifouling device for the hull. A bio magnet for unwanted creatures ? As you have no drag under engine and sail, the perfect solution for all fouling problems.

Peter /forums/images/graemlins/grin.gif
 
I would mount a couple of big anodes either side of the rudder. Apart from the obvious protection to the rudder, it also seems to help hold paint onto the stainless - I have lower rudder fittings made from stainless.
 
Quote:
--------------------------------------------------------------------------------

Trade secrets here
THIS INFORMATION IS NOT PUBLISHED OR ENDORSED BY PAINT MANUFACTURERS FOR PURPOSES OF GUARANTEE PARTICULARLY IN THE DIY MARKET, I WAS AN APLICATOR FOR A RESEARCH COMPANY THAT HAD PAINT TECHNICIANS RESEARCHING THIS VERY SUBJECT AS WELL AS OTHER MARINE COATINGS.

Stainless like copper theoretically can not be painted to a finish that lasts for a reasonable ammount of time in any product so that a paint manufacturer can sell a product that is guaranteed on any of these substrates.


--------------------------------------------------------------------------------

Funny that, Stainless steel is painted on occassions for use in "marine environments" and the coatings do last - up to 25 years or more

POWDER COATING OR FACTORY COATED, NOT DIY OR BOAT YARD, THE TECHNIQUES AND PAINTS ARE NOT READILLY AVAILABLE FOR ANY COATING THAT WILL LAST ON STAINLESS.

Quote:
--------------------------------------------------------------------------------

However if you do choose to paint stainless, the best way to do so is as follows, (as you quite rightly point out that the primer has given way)

Assuming you are starting with bare stainless,

Abrade the stainless with a grinder and an 80 grit grinder disc to form a key.

wash any contaminants off with a de-greaser, a few applications are usually required, wash on and wipe off with clean lint free cloths.

Heat the stainless with a hot air gun so as that it is warm but not so hot that it starts discolouring or buckling out of shape.

This will enable the pores in the steel to expand allowing the first coat of slightly thinned out epoxy (2 part) primer (approx 15%-20% thinned) to soak in. Check data sheets for the primer that it can withstand high temperatures, as well as having a high flash point (as most epoxy primers do)


--------------------------------------------------------------------------------

Pores in stainless steel? if you have then scrap the material. Commercially available Stainless Steel is not porous.

GOOGLE "MACROPORES STAINLESS STEEL" IT IS THE MACROPORES THAT HEAT UP AND EXPAND ON A MOLECULAR LEVEL WHICH IS WHY FACTORY POWDER COATINGS ARE HEATED.

Quote:
--------------------------------------------------------------------------------

When the steel cools and the pores of the steel contract they will allow a bond between the primer and hte steel. Although this is not a perfect bond it is the best way to get a bond outside of a coatings factory.


--------------------------------------------------------------------------------

Says who? - I have never read such nonsense about painting/coating in my life. Are you actually just taking the pi$$ or do you really believe such rubbish?

AS STATED ABOVE THIS INFORMATION ALTHOUGH CORRECT IS NOT PUBLISHED.

Quote:
--------------------------------------------------------------------------------

When the primer is tacked off, ie when you touch it the paint does not stick to your finger but leaves a slight impression, (5-10 mins) depending on primer manufacturer, apply by brush or spray a second coat of primer.

This second coat, allows a sufficient product build so that the first coat grips in but the second coat acts as a barrier or protection.


--------------------------------------------------------------------------------

And traps solvents etc and inhibits the proper curing of the prime coat resulting in a poor. low strength base coat thich would be prone to failure.

AS STATED DEPENDING ON MANUFACTURER, I WILL ELABORATE, THE MAJORITY OF EPOXY PRIMERS ARE MANUFACTURED FOR WET ON WET APPLICATION, THIS IS WHERE ANOTHER COAT CAN BE APPLIED PRIOR TO DRYING, CHEMICALLY BONDED EPOXIES FORM A STRONGER THAN REACTIVATING THE PREVIOUS COAT 24 HOURS LATER WITH A SECOND COAT. MOST PROFESSIONAL EPOXY PAINT APPLICATORS PREFER TO USE THE WET ON WET SYSTEM.

Quote:
--------------------------------------------------------------------------------

Just after the second primer coat tacks off, apply 1 coat of antifoul. This creates a chemical bond between the antifoul and primer. If this is not done, theoretically the antifoul can peel off sooner than expected and the primer will be eroded by the marine environment.

You can now follow the antifoul manufacturers application recomendations for further antifoul coating. However 3-4 coats at 30-90 min intervals on a warm dry day would be good.


--------------------------------------------------------------------------------


I trust you do not apply antifoul or any other paint system "professionally".

I HAVE PREVIOUSLY WORKED IN THE MARINE INDUSTRY AND WAS REGULARLY RECOMENDED BY SEVERAL PAINT MANUFACTURERS.
 
I HAVE PREVIOUSLY WORKED IN THE MARINE INDUSTRY AND WAS REGULARLY RECOMENDED BY SEVERAL PAINT MANUFACTURERS.

Very fortunate that you said "previously" 'cos I would hate to find that I ended up with you involved with one of my managed new builds.

What a lot of twaddle and is unfortunate you are trying to lead others astray with claims of professionalism.

John
 
Hear, hear.

Well said, I have never heard such "twaddle" as you call it (I have another name for it). The poster obviously does not have a clue about either metallurgy or paint systems - either that or he is "on something" or not from this planet - now there's a thought - maybe the clue is in the name? /forums/images/graemlins/smirk.gif.

AS STATED ABOVE THIS INFORMATION ALTHOUGH CORRECT IS NOT PUBLISHED.

I wonder why it is not published? could it be because whoever published such rubbish would be subject to so much ridicule by those who DO know about materials, porosity, surface treatments, paint systems etc. To put one's name to such bull_ _it would be commercial suicide.

I HAVE PREVIOUSLY WORKED IN THE MARINE INDUSTRY AND WAS REGULARLY RECOMENDED BY SEVERAL PAINT MANUFACTURERS.

Worked as what? Recommended for what? Instant dismissal on grounds of total incompetence? Dildo of the month award?

I would hope readers of this thread realise who is "full of it" and those who actually know what they are talking about and offer sound advice rather than yacht club bar gossip.
--------------------
hammer.thumb.gif
"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
 
We had 2 SS rudders on out Catalac, just used normal AF and primer. You need to fit anodes. On our string of moorings ours was the only one that need to have the anode fitted to the chain replaced each year.
 
Reminds me of a Television infomercial I saw on Dutch TV some years ago. A (is the right word "buxom"?) lady applied her "Wonder-polish" to a stainless steel table to... "FEED THE METAL".
 
Have you considered getting it plated with copper - either electroplated or flame-sprayed? Not DIY, but probably not too expensive at a plating shop. It would be harder-wearing than paint.
 
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