AIDY
Well-Known Member
How should i treat a rusty keel before slapping some A/F over it.
First thought was to wire brush then treat with red oxide paint.
First thought was to wire brush then treat with red oxide paint.
rusty keel
- Thread starter AIDY
- Start date
earlybird
Well-Known Member
I cleaned mine off to a reasonable standard with angle grinder and abrasive discs,(not grinding discs ), this is a fairly dirty, tedious job. Then put on 4 or 5 coats of International Primocon. This seemed to last fairly well.
Spuddy
Well-Known Member
Very recent posts mentioned hired needle guns to clean up. Worth digging back to weigh up which of the recommendations for potions to slap on you prefer.
Allanrichard
Member
http://www.ybw.com/forums/showflat.php/Cat/0/Number/1774792/an/0/page/0
This link may help. I have the same problem!
This link may help. I have the same problem!
Grajan
Well-Known Member
Dont use red oxide it is not designed for U/W use, abraid with disc, wire brushing only polishes the steel/casting then apply 5 coats of Primocon
AIDY
Well-Known Member
Thank you... international primocon it is then
oldsaltoz
Well-Known Member
G'day Arnold,
Cast iron is porous due to impurities like sand and temperatures etc from casting;
To clean it you need a constant flow of clean material to remove [--word removed--] without leaving other contaminants behind.
This should indicate that anything that rotates like Grinding or sanding and Wire brushing will all present a dirty surface as they rotate and return material still contaminated. Needle guns will poke or push contamination into the small voids and only delay the next eruption.
The aim should be to not only clean the keel but also prevent moisture and oxygen getting to the surface. Cast iron will flash rust, rust will begin forming in a few minutes, so need to get 'some' protection on quickly.
You need to start with a dry keel.
You need to blast it to class 2.5 (no shadows).
You need to apply some protection during the blasting operation.
You may also need to fill in the voids left after a proper clean.
Fin Keels:
When shot blasting, start with the bottom of the keel and work from one end to the other, then do each side of the keel, follow the grit nozzle and apply a coat of epoxy resin work from top to bottom in 4" to 6" (100 to 150mm) strips. complete each side of the keel.
You now have a dry and sealed rough looking keel, apply a second coat of epoxy to ensure no areas have been missed, do this with an 80 mm roller, fast and effective. Allow this to cure for a minimum of 24 hour above 20*C and below 73% humidity; If you don't have these conditions, create them or wait for them, or waste your time and money.
After curing and a washing, give the treated area a light sanding by hand with a 200 grit paper, just enough to remove most of the high gloss.
use 'Closed Cell' balloons mixed with an epoxy resin will fill any low areas and let them cure as above, after all lows have been filled and sanded apply at least 3 or f more coats of epoxy resin to provide protection for the cast iron from moisture and oxygen.
After curing wash then sand as above and coat with a high build epoxy primer then your choice of antifoul (or as some do) a coat of the same paint you see on piles in marinas and cover this with antifoul.
Hope this helps.
Avagoodweekend......
Cast iron is porous due to impurities like sand and temperatures etc from casting;
To clean it you need a constant flow of clean material to remove [--word removed--] without leaving other contaminants behind.
This should indicate that anything that rotates like Grinding or sanding and Wire brushing will all present a dirty surface as they rotate and return material still contaminated. Needle guns will poke or push contamination into the small voids and only delay the next eruption.
The aim should be to not only clean the keel but also prevent moisture and oxygen getting to the surface. Cast iron will flash rust, rust will begin forming in a few minutes, so need to get 'some' protection on quickly.
You need to start with a dry keel.
You need to blast it to class 2.5 (no shadows).
You need to apply some protection during the blasting operation.
You may also need to fill in the voids left after a proper clean.
Fin Keels:
When shot blasting, start with the bottom of the keel and work from one end to the other, then do each side of the keel, follow the grit nozzle and apply a coat of epoxy resin work from top to bottom in 4" to 6" (100 to 150mm) strips. complete each side of the keel.
You now have a dry and sealed rough looking keel, apply a second coat of epoxy to ensure no areas have been missed, do this with an 80 mm roller, fast and effective. Allow this to cure for a minimum of 24 hour above 20*C and below 73% humidity; If you don't have these conditions, create them or wait for them, or waste your time and money.
After curing and a washing, give the treated area a light sanding by hand with a 200 grit paper, just enough to remove most of the high gloss.
use 'Closed Cell' balloons mixed with an epoxy resin will fill any low areas and let them cure as above, after all lows have been filled and sanded apply at least 3 or f more coats of epoxy resin to provide protection for the cast iron from moisture and oxygen.
After curing wash then sand as above and coat with a high build epoxy primer then your choice of antifoul (or as some do) a coat of the same paint you see on piles in marinas and cover this with antifoul.
Hope this helps.
Avagoodweekend......
Vamoose
Well-Known Member
Mine was pretty bad and I knew it needed shot blasting.. Immediatly afterwards on the advice of International I gave it 1 coat of Interprotect, then filled pits with International Watertite, then 4 more coats of Interprotect..
As it has been taken back to the base I am coating the keel with Coppercoat. It hasnt been a chep excercise but I hoping that it will pay dividends in the long run. Ask me again in 12 months how its performed !
As it has been taken back to the base I am coating the keel with Coppercoat. It hasnt been a chep excercise but I hoping that it will pay dividends in the long run. Ask me again in 12 months how its performed !
AIDY
Well-Known Member
thank you i will have a look at the various options from international on their website. I think i went wrong last year by putting some old hammerite on first that i had in the garage.
vyv_cox
Well-Known Member
My keel has just been grit blasted. The yard have applied five coats of clear epoxy as a primer and base, now fairing with epoxy plus filler, then a final coat of epoxy. I will then Coppercoat it.
The previous gritblasting lasted more than 10 years, also with Coppercoat on top. I never did a thing to it all those years, with about half of the winters afloat. Finally the water got beneath the initial coating and the keel rusted rapidly. I regard it as having been a great success, saved me hours of kneeling down antifouling, grinding and patching up rust spots.
The hull is conventionally antifouled, I don't mind doing that so much.
The previous gritblasting lasted more than 10 years, also with Coppercoat on top. I never did a thing to it all those years, with about half of the winters afloat. Finally the water got beneath the initial coating and the keel rusted rapidly. I regard it as having been a great success, saved me hours of kneeling down antifouling, grinding and patching up rust spots.
The hull is conventionally antifouled, I don't mind doing that so much.