npf1
Active member
My anodes have lots of metal left on them but are partially covered in a white deposit. I read a recent article that said anodes should never be cleaned. Can anyone explain why?
Cleaning Anodes
- Thread starter npf1
- Start date
Bodach na mara
Well-known member
I can't explain why they should not be cleaned as I was told to wire brush mine to remove the deposit and expose the zinc.
alan
Active member
I always wire brush mine as well, as I figured that the white deposit would inhibit the small electrolytic currents - but I could be (as usual) quite wrong!!!
Alan.
Alan.
Swagman
New member
I understood the white deposit is the degraded zinc and removal will make the anode more effective, but it should then erode quicker.
I've always also used a wire brush as anodes costs less than a prop - but guess we should all assume the recommneded sized anode with the deposit on should still be operating to its specification.
Or should we?
If any one has the scentific answer - maybe a Mr Anode Maker himself - love to clear this one up.
Cheers
JOHN
I've always also used a wire brush as anodes costs less than a prop - but guess we should all assume the recommneded sized anode with the deposit on should still be operating to its specification.
Or should we?
If any one has the scentific answer - maybe a Mr Anode Maker himself - love to clear this one up.
Cheers
JOHN
BrendanS
Well-known member
With my scientific hat on
The white deposit is oxidised zinc, and once it is coating the surface of the anode, it will effectively provide an insulation layer. So, the deposits should be removed, or the anode will not be functioning as well as a non-oxidised one. Sandpaper or scraping work well.
If the anode is significantly reduced in size and coated, then better to replace.
The white deposit is oxidised zinc, and once it is coating the surface of the anode, it will effectively provide an insulation layer. So, the deposits should be removed, or the anode will not be functioning as well as a non-oxidised one. Sandpaper or scraping work well.
If the anode is significantly reduced in size and coated, then better to replace.
Vara
Active member
With my non scientific hat on cos sacrificial protection seems to be black magic with some science added to give it respectability.
I would say that replacing anodes is a bit like reefing,if your thinking about it;do it!
Better in both cases to do too much than too little.
With scientific hat on I would say that if you have lots of white deposits on an anode it may indicate that the zinc is acting as zinc and not as an anode,in which case you may want to check your bonding to whatever the anode is meant to be protecting.
PS What does a scientist's hat look like?
I would say that replacing anodes is a bit like reefing,if your thinking about it;do it!
Better in both cases to do too much than too little.
With scientific hat on I would say that if you have lots of white deposits on an anode it may indicate that the zinc is acting as zinc and not as an anode,in which case you may want to check your bonding to whatever the anode is meant to be protecting.
PS What does a scientist's hat look like?
VicMallows
New member
As the others have said, the information you've been given sounds ludicrous. Are you sure they didn't say 'you must never PAINT them'?
Vic
Vic
Cantata
Well-known member
I read somewhere a while ago that it's the wire-brushing that's the problem, not the cleaning itself. Apparently the surface of the anode is changed chemically in some way by the action of the brush.
I'm only reporting what I read - no I don't understand it either, but have ever since then used emery to clean anodes, which have then continued to work.
Perhaps the anti-wire-brusher will raise his/her head?
I'm only reporting what I read - no I don't understand it either, but have ever since then used emery to clean anodes, which have then continued to work.
Perhaps the anti-wire-brusher will raise his/her head?
VicMallows
New member
Or that everything is passive in its environment and the anode does not need to errode?
Vic
Vic
BrendanS
Well-known member
Some purist may say that using metal brushes may contaminate the anode and affect it's composition, thereby reducing it's effectiveness, so only use stainless steel or non metallic brushes, but in the real world, I really wouldn't worry about it. Such purity is only necessary when anodes are being used in plating or other similar processes, not when on boats.
Use sandpaper if you feel happier, but it's really not going to have a significant effect.
I can think of other reasons for not using metallic brushes though, not least of which is the chance of damaging the coating on aluminium (eg on sterndrives) close to the anode, or the chance of bits of ferrous metal getting embedded in glassfibre and then rusting (been there, done that, when I hacksawed off the shackle off an anchor and ended up with speckles of rust all over the gelcoat in the area!)
Use sandpaper if you feel happier, but it's really not going to have a significant effect.
I can think of other reasons for not using metallic brushes though, not least of which is the chance of damaging the coating on aluminium (eg on sterndrives) close to the anode, or the chance of bits of ferrous metal getting embedded in glassfibre and then rusting (been there, done that, when I hacksawed off the shackle off an anchor and ended up with speckles of rust all over the gelcoat in the area!)
VicS
Well-known member
Brendan,
Perhaps they could be cleaned with oxalic acid, mixed with wallpaper paste of course. It seems to be the magic 'clean all' chemical of the moment. What do you think? /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif
The problem with wire brushing could be that bits of wire left imbedded in the anode will accelerate the the rate of loss of zinc.
Vic
Perhaps they could be cleaned with oxalic acid, mixed with wallpaper paste of course. It seems to be the magic 'clean all' chemical of the moment. What do you think? /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif
The problem with wire brushing could be that bits of wire left imbedded in the anode will accelerate the the rate of loss of zinc.
Vic
BrendanS
Well-known member
Never mind Oxalic acid, a good dose of concentrated phosphoric acid will have the anodes clean in no time! <gg>
I still don't think in the real world that bits of wire embedded in the zinc is likely. On the odd chance you do get a bristle embedded, then you can just pull it out. The tiny amount of metal lost through abrasion isn't going to hang around long.
As I said in an early post in the thread, if anyone thinks it's worth worrying about, just use stainless brush, or sandpaper.
I still don't think in the real world that bits of wire embedded in the zinc is likely. On the odd chance you do get a bristle embedded, then you can just pull it out. The tiny amount of metal lost through abrasion isn't going to hang around long.
As I said in an early post in the thread, if anyone thinks it's worth worrying about, just use stainless brush, or sandpaper.
VicS
Well-known member
Stainless wire left imbedded in the zinc will be worse than mild steel wire.
Phosphoric won't be a good choice because zinc phosphate is insoluble.
I thought you might have pulled me up over the insolubility of zinc oxalate!
Phosphoric won't be a good choice because zinc phosphate is insoluble.
I thought you might have pulled me up over the insolubility of zinc oxalate!
BrendanS
Well-known member
[ QUOTE ]
Phosphoric won't be a good choice because zinc phosphate is insoluble.
I thought you might have pulled me up over the insolubility of zinc oxalate!
[/ QUOTE ]
Eek, thought we were joking! Too late at night to think about insolubility of anything
The reason most anode people recommend stainless steel brushes is that they are tough, and so very unlikely to leave bits behind, rather than soft wire metal brushes
Phosphoric won't be a good choice because zinc phosphate is insoluble.
I thought you might have pulled me up over the insolubility of zinc oxalate!
[/ QUOTE ]
Eek, thought we were joking! Too late at night to think about insolubility of anything
The reason most anode people recommend stainless steel brushes is that they are tough, and so very unlikely to leave bits behind, rather than soft wire metal brushes
npf1
Active member
Thanks for the responses. Seems that common sense previals!
ex-Gladys
Well-known member
Our anodes have got covered in calciofication in the past. Vinegar does a grand job getting rid of the scaling
