What is the best method of stopping corrosion and protecting the aluminum parts from further corrosion. Specifically, while the mast-base cast was recently replaced by the last owner, there is corrosion around old rivet holes (and possibly more). I would like to know how others have handled this. I'm thinking of using an etch like phosphoric acid prior to a zinc chromate spray. My 1989 h-23 is overall in great shape and I also would like to find Central Florida sailors to sail/race with.
Stopping Corrosion
- Thread starter RichB
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Sources refer to phosphoric acid as "anodizing"
aluminium. Here's a link that says (if I deciphered it right) that when they tested adhesives stuck to aluminium that had been anodized with phosphoric acid, then broke both the metal and the bond in various ways, the adhesives stuck really well. It's worth a read just for the jargon. It sounds like you're on the right track. Phosphoric acid takes away the corrosion and leaves a surface that will hold paint or glue. My reading says the surface needs to be coated after phosphoric acid, because the "primer" it leaves is thin and easily damaged. Pete Culler wrote somewhere that "an old dory shop treatment for aluminium is to wipe on diesel oil with a rag". I would say, since cheap paint thinner is a very high grade of kerosene (much like diesel), mix some oil base paint or varnish or linseed or neets foot oil or pine tar with a bit of thinner and it will probably penetrate and harden on aluminium in hard to reach places, especially if you use phosphoric acid first. If you can get good pine tar it leaves a really cool aroma. That ought to get a rise out of somebody.
aluminium. Here's a link that says (if I deciphered it right) that when they tested adhesives stuck to aluminium that had been anodized with phosphoric acid, then broke both the metal and the bond in various ways, the adhesives stuck really well. It's worth a read just for the jargon. It sounds like you're on the right track. Phosphoric acid takes away the corrosion and leaves a surface that will hold paint or glue. My reading says the surface needs to be coated after phosphoric acid, because the "primer" it leaves is thin and easily damaged. Pete Culler wrote somewhere that "an old dory shop treatment for aluminium is to wipe on diesel oil with a rag". I would say, since cheap paint thinner is a very high grade of kerosene (much like diesel), mix some oil base paint or varnish or linseed or neets foot oil or pine tar with a bit of thinner and it will probably penetrate and harden on aluminium in hard to reach places, especially if you use phosphoric acid first. If you can get good pine tar it leaves a really cool aroma. That ought to get a rise out of somebody.
Corrosion X
I have used Corrosion X succesfully to stop the corrosion of my aluminum toerails that cause black streaks on my topsides. It's very effective, I saw the results immediatly
I have used Corrosion X succesfully to stop the corrosion of my aluminum toerails that cause black streaks on my topsides. It's very effective, I saw the results immediatly
Naval jelly
which is available from a good hardware store for < $10 for a 10 oz jar contains phosphoric acid as the active ingredient. It is primarily intended for use on rusted iron and steel but also on all galvanized surfaces. The phosphoric acid leaves a white substrate on the old iron heaters I have been restoring lately. The trick is to remove all the substrate before painting or gluing after leaving on for an appropriate "dwell" time. The substrate is chemically a plant fertilizer (read: contains phosphates) and can be brushed off with a wire brush or washed off with water and a rag. Fred is right, you are on the right track. The link below is for the type of Naval jelly used in commercial applications. The stuff I bought recently was a pink loose gel that I painted on with a chip brush.
which is available from a good hardware store for < $10 for a 10 oz jar contains phosphoric acid as the active ingredient. It is primarily intended for use on rusted iron and steel but also on all galvanized surfaces. The phosphoric acid leaves a white substrate on the old iron heaters I have been restoring lately. The trick is to remove all the substrate before painting or gluing after leaving on for an appropriate "dwell" time. The substrate is chemically a plant fertilizer (read: contains phosphates) and can be brushed off with a wire brush or washed off with water and a rag. Fred is right, you are on the right track. The link below is for the type of Naval jelly used in commercial applications. The stuff I bought recently was a pink loose gel that I painted on with a chip brush.
Here's a semi serious link about dental use of
phosphoric acid. The short story is that phosphoric acid made the glue stick best, (better than the high priced spread) but it eroded the tooth enamel. If you want to glue your teeth to the mast, phosphoric acid my not be the way to go, but the stuff seems to be the ultimate primer. The white powder left on steel after Phosphoric acid is generally considered to be OK to paint right over after a wipe with a rag. I don't know about aluminium.
phosphoric acid. The short story is that phosphoric acid made the glue stick best, (better than the high priced spread) but it eroded the tooth enamel. If you want to glue your teeth to the mast, phosphoric acid my not be the way to go, but the stuff seems to be the ultimate primer. The white powder left on steel after Phosphoric acid is generally considered to be OK to paint right over after a wipe with a rag. I don't know about aluminium.
This has become a learning experience. Thanks very much. I can now proceed with less trepidation. (I was afraid to put acid on the aluminum) 1. CorrosionX. refered by b393capt. It apparently comes in marine (red can) grade which is a 'do-all' product to spray on everything metal. It also comes in Aviation (blue can) grade specifically to arrest corrosion on aircraft sheet metal. I assume this super penetrant property will run-off in time and therefore become a yearly chore. 2. Phosphoric acid discussed by Fred and CalebD is an anodizing agent. Following the etch with zinc chromate should provide a permanent solution in static places. ie: corrosion on the surface inside the mast. Any place there is even micro movement like the pop rivets penetrations, the resulting abrasion will allow a new colony of oxide. So.... muchlike "CorrosionX", the diesel/pine tar combination can provide the same penetration but with the stickiness to keep the aluminum sealed longer. So the answer really is Pine Tar! Aswith BenGay, the added benefit is the smell. It looks like a new product idea has just sprouted. A pine Tar dip to be used whenever riveting or screwing anything to your extrusions. Move over CorrosionX.
Rich, you're my Man! Pine Tar still belongs in
the modern tool kit. Did you look at the dental link? Maybe I'm truly strange (maybe?) but I found it fascinating.
the modern tool kit. Did you look at the dental link? Maybe I'm truly strange (maybe?) but I found it fascinating.
stopping corrosion - FRED
The Interlux paint guidebook states that you must prime aluminum within one hour of cleaning/blasting the corroded surface. This isn't an unreasonable challange, but it says something of the nature of the beast. The oxide barrier (white rust) that forms, does so quickly. Any coating applied without scrupluous adherance to the rules of aluminum is doomed to failure. Yes I went to the dental site. I didn't like the observation that the enamel is dissolved. Quote-(( "that Megabond self-etching primer produced less dissolution of enamel surface than did phosphoric acid and polyacrylic acid etching.")) But I guess that is why it is called etching. I wonder if they tried Coca Cola? I just want to be sure the etching process stops before it reduces the mast to swiss cheese. To that end I emailed a local metal finishing company. The response didn't indicate a molecular level knowledge....Maybe they didn't actually read the whole question. Perhaps they smell a customers money. When you use baking soda in the battery compartment of your car, you know that no damage can result. As this relates to aluminum, I would like to know if the reaction has a natural stopping point prior to the swiss cheese effect. It's time to experiment with the acid. Meantime apply a liberal dob of pine tar and diesel to the mast.
The Interlux paint guidebook states that you must prime aluminum within one hour of cleaning/blasting the corroded surface. This isn't an unreasonable challange, but it says something of the nature of the beast. The oxide barrier (white rust) that forms, does so quickly. Any coating applied without scrupluous adherance to the rules of aluminum is doomed to failure. Yes I went to the dental site. I didn't like the observation that the enamel is dissolved. Quote-(( "that Megabond self-etching primer produced less dissolution of enamel surface than did phosphoric acid and polyacrylic acid etching.")) But I guess that is why it is called etching. I wonder if they tried Coca Cola? I just want to be sure the etching process stops before it reduces the mast to swiss cheese. To that end I emailed a local metal finishing company. The response didn't indicate a molecular level knowledge....Maybe they didn't actually read the whole question. Perhaps they smell a customers money. When you use baking soda in the battery compartment of your car, you know that no damage can result. As this relates to aluminum, I would like to know if the reaction has a natural stopping point prior to the swiss cheese effect. It's time to experiment with the acid. Meantime apply a liberal dob of pine tar and diesel to the mast.
diesel (antioxident)
for many years truck drivers have been rejuvinating their trucks by wiping them down with a cloth saturated with diesel fuel old oxidized paint aluminum fuel tanks stainless steel hand rails and chrome exhaust pipes i've tried this on several myself over the years and had very good success the only draw back is it collects dust so we have to wipe our trucks more often but i dont think thats a problem in this aplication
for many years truck drivers have been rejuvinating their trucks by wiping them down with a cloth saturated with diesel fuel old oxidized paint aluminum fuel tanks stainless steel hand rails and chrome exhaust pipes i've tried this on several myself over the years and had very good success the only draw back is it collects dust so we have to wipe our trucks more often but i dont think thats a problem in this aplication
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