Hi,
I know that this possibly has a simple answer that everyone but me
knows, but is there any way I can prevent the unslightly brown "rust"
marks on my white hull paint from a welded fabricated stainless steel
fitting that is bolted on with stainless bolts?

I am about to spray on the white topcoat over the primer during a hull
repaint job and I'd like it to stay looking good.

I suspect that the drop ladder on the stern is not made entirely of
316. It has been 15 years since I fitted it, so that I can't recall
whether the bolt is 316, 304 or (unlikely) something else. There are
no 316 markings on the bolt heads.

We use oxalic acid powder mixed with water to get rid of it but it
always comes back. I am beginning to quote Lady MacBeth when I rub it
away ("out foul spot") and it's embarrassing when passersby overhear.
I know that there are several (expensive) "special" products to clean
it with but I would appreciate some knight on a white charger offering
me a permanent fix. It doesn't matter if he's young or old, handsome
or otherwise - I'm not playing Sleeping Beauty - so long as he or she
has the answer.

I wonder whether it would be possible to electrically isolate it with
say, a teflon washer?

cheers
Peter
(who actually sails places and doesn't pretend to)

On Sat, 24 Mar 2007 12:44:13 GMT, Rich Hampel
wrote:

Probability is that the welds are not ground flat and smooth and
crevice corrosion is underway in the 'intersticies' of the weldment
(poor weld technique ... not a full penetration weld).

To be 'corrosion resistant' (chlorides, etc. attack stainless) all the
weld must be flat /smooth by grinding and then polishing/buffing to a
high mechanical mirror polish. Any 'weld-lap' or pin-hole in the weld
will be a source of 'rust' .... gotta be closed and then smoothed. .


This has just made sense as only one of the bolt on "feet" for the
ladder suffers from the problem. I'll try it.

Thanks very much to all who responded.

regards
Peter Hendra

Peter Hendra wrote:
Hi,
I know that this possibly has a simple answer that everyone but me
knows, but is there any way I can prevent the unslightly brown "rust"
marks on my white hull paint from a welded fabricated stainless steel
fitting that is bolted on with stainless bolts?

I am about to spray on the white topcoat over the primer during a hull
repaint job and I'd like it to stay looking good.

I suspect that the drop ladder on the stern is not made entirely of
316. It has been 15 years since I fitted it, so that I can't recall
whether the bolt is 316, 304 or (unlikely) something else. There are
no 316 markings on the bolt heads.

We use oxalic acid powder mixed with water to get rid of it but it
always comes back. I am beginning to quote Lady MacBeth when I rub it
away ("out foul spot") and it's embarrassing when passersby overhear.
I know that there are several (expensive) "special" products to clean
it with but I would appreciate some knight on a white charger offering
me a permanent fix. It doesn't matter if he's young or old, handsome
or otherwise - I'm not playing Sleeping Beauty - so long as he or she
has the answer.

I wonder whether it would be possible to electrically isolate it with
say, a teflon washer?

cheers
Peter
(who actually sails places and doesn't pretend to)
where is the rust comming from
the weld or the mounting point
or the bolts them selfs
Shaun

On Fri, 23 Mar 2007 19:22:33 +1100, Peter Hendra
wrote:

I know that this possibly has a simple answer that everyone but me
knows, but is there any way I can prevent the unslightly brown "rust"
marks on my white hull paint from a welded fabricated stainless steel
fitting that is bolted on with stainless bolts?

My first reaction would be to prime and paint the stainless but that
might have its own issues.

Probability is that the welds are not ground flat and smooth and
crevice corrosion is underway in the 'intersticies' of the weldment
(poor weld technique ... not a full penetration weld).

To be 'corrosion resistant' (chlorides, etc. attack stainless) all the
weld must be flat /smooth by grinding and then polishing/buffing to a
high mechanical mirror polish. Any 'weld-lap' or pin-hole in the weld
will be a source of 'rust' .... gotta be closed and then smoothed. .


In article , Peter Hendra
wrote:

Hi,
I know that this possibly has a simple answer that everyone but me
knows, but is there any way I can prevent the unslightly brown "rust"
marks on my white hull paint from a welded fabricated stainless steel
fitting that is bolted on with stainless bolts?

I am about to spray on the white topcoat over the primer during a hull
repaint job and I'd like it to stay looking good.

I suspect that the drop ladder on the stern is not made entirely of
316. It has been 15 years since I fitted it, so that I can't recall
whether the bolt is 316, 304 or (unlikely) something else. There are
no 316 markings on the bolt heads.

We use oxalic acid powder mixed with water to get rid of it but it
always comes back. I am beginning to quote Lady MacBeth when I rub it
away ("out foul spot") and it's embarrassing when passersby overhear.
I know that there are several (expensive) "special" products to clean
it with but I would appreciate some knight on a white charger offering
me a permanent fix. It doesn't matter if he's young or old, handsome
or otherwise - I'm not playing Sleeping Beauty - so long as he or she
has the answer.

I wonder whether it would be possible to electrically isolate it with
say, a teflon washer?

cheers
Peter
(who actually sails places and doesn't pretend to)

On Mon, 26 Mar 2007 17:56:36 GMT, "Gordon Wedman"
wrote:



A friend has gone thru this with his stainless. People at his workplace
that know about his sort of thing told him he needed to passivate the welds.
They gave him some solution to paint on the welds. I believe this is
hydrofluoric acid, perhaps a mixture with other acids. Requires very
carefull application. It took away the surface shine. Don't recall the
final result but I can ask him.


Thanks for this Gordon,
At the moment the offending articles are sheathed by masking tape as I
am halfway through spray painting the hull.

I would very much appreciate you asking your friend if it is not too
much trouble. The more information about this, the better.

When it was welded, it, like all other Stainless welds was brushed
with that nitric acid gel solution that then is washed off with water,
and which removes the discolouration from the tig/mig/arc welding
process. Is this the same thing? I can't recall getting anything
"passivated".

Thanks and cheers
Peter

"Peter Hendra" wrote in message
...
On Sat, 24 Mar 2007 12:44:13 GMT, Rich Hampel
wrote:

Probability is that the welds are not ground flat and smooth and
crevice corrosion is underway in the 'intersticies' of the weldment
(poor weld technique ... not a full penetration weld).

To be 'corrosion resistant' (chlorides, etc. attack stainless) all the
weld must be flat /smooth by grinding and then polishing/buffing to a
high mechanical mirror polish. Any 'weld-lap' or pin-hole in the weld
will be a source of 'rust' .... gotta be closed and then smoothed. .


This has just made sense as only one of the bolt on "feet" for the
ladder suffers from the problem. I'll try it.

Thanks very much to all who responded.

regards
Peter Hendra

A friend has gone thru this with his stainless. People at his workplace
that know about his sort of thing told him he needed to passivate the welds.
They gave him some solution to paint on the welds. I believe this is
hydrofluoric acid, perhaps a mixture with other acids. Requires very
carefull application. It took away the surface shine. Don't recall the
final result but I can ask him.

On Tue, 27 Mar 2007 16:53:07 +0700, Bruce
wrote:


I've been reading some of your other posts -- do you reckon that your
paint job is cheaper, or more expensive then it wold be in Malaysia?



Bruce in Bangkok
(brucepaigeatgmaildotcom)

Hi Bruce,
Thanks for the info.

It looks as if I shall have to take my stern ladder off and polish it
as you say. Yes, I always use Sikaflex.

As to the relative cost of the paint job, haven't really done the
sums. I have to get it done so I just spend what I need to. The paint
is relatively the same - I am using Ameron - made by the people who
own the yard. In Malaysia I used Jotan antifouling which I bought in a
20 litre drum from Singapore and had ferried up to Langkawi by a
series of patrol boats (free of course). I can't recall the price but
it seems rather expensive here. I am considering ABC3 but have to test
it on a metre square patch as to whether it will adhere to the
existing Jotan (I should post an enquiry regarding this).

The other difference and increase in cost for me is that in Malaysia I
had free use of the 30 ton travel lift at our Langkawi Marine Customs
base as well as the large new shed to paint in. Here I am paying yard
fees and small extras such as daily rental for planks and scaffolding.
There is an extra daily charge for living on the boat whilst in the
yard. I plan to take my mast down and renew the rigging and do a
number of other things. Rental is also charged on the mast whilst it
is on the ground.

In Langkawi there is an excellent stainless workshop as well as
experienced electrical and mechanical engineers - all very cheap.
Here, prices for labour and services are much dearer, partly due to
the large American and other customers who are happy to pay the
somewhat cheaper cost than in the US.

One price I do know that you should be able to trealte to was the cost
of having two hatches re-teaked - US$75 per square foot.

Also, here I have no car so have to purchase most groceries at the
local minimarket which has marina pricing unless I want to take half a
day off to buy only that which I can carry on a maxi taxi. In Langkawi
I could have my meals at the Customs Base.

Another difference, not factored in any financial calculations, is
that here there are many like minded souls who are able to give advice
regarding things boating. In Malaysia, by nature of my job and the
close knit family style of Customs and because my wife and son were
with me, I mainly socialised with locals and met few yachtees.
Actually, many of the later disliked me before they had met me as many
were annoyed that I had access to Customs bases and facilities
throughout the country. One even officially approached the commander
of the Penang base and asked why he was not able to tie up there,
leave his dinghy there in security and get water etc. as I did. No
amount of telling them that I worked for Customs seemed to satisfy
them. Also, I was regarded with suspicion (sometimes in quite a
hostile manner) by some as a lot of yachtees sailed up from places
like the marina at Port Dixon to load their boats with duty free
cigarettes and alcohol which they sold or shared with their
neighbours. They expected me to do something about it and curb their
activities but frankly I and we had other priorities and never worried
much about yachts. We knew of it but let it pass as Customs is kept
busy by contraband smugglers, the heroin traffic from Thailand, and
human trafficking. One specially built GRP boat with three new Mercury
200HP outboards bringing 2.5 tons of cigarettes from Indonesia avoids
$615,000 Ringit of duty (US$178,000). I have seen two of these
apprehended in one night at the Port Klang base.

Besides, many of these yachtees I had nothing in common with anyway
and they had spent years drinking and socialising in the one place as
a way of life. They won't leave and there are those that finance
themselves by selling off vital equipment from their boats. There were
others, however, who were great company such as Bob and Ely and their
delightful two little boys who, at aged 4 and 5 could climb to the
spreaders - no mast steps, just pull themselves up a halyard - and sit
and eat their bag of potato chips. Bob, a retired military man, a rock
conservative fundamentalist Christian from the Mid-West, who at age
75 is on his third marriage, will help anyone with their radio or
electronics. He now is moored at a Marine base in Penang most of the
time - a wonderful man.

Hey, I apologise - I got carried away.

Yes, thinking about it - it is cheaper in Malaysia but commercial
haulout is much dearer there.

cheers
Peter

On Tue, 27 Mar 2007 20:51:00 +1200, Eric Stevens
wrote:

On Mon, 26 Mar 2007 17:56:36 GMT, "Gordon Wedman"
wrote:


"Peter Hendra" wrote in message
. ..
On Sat, 24 Mar 2007 12:44:13 GMT, Rich Hampel
wrote:

Probability is that the welds are not ground flat and smooth and
crevice corrosion is underway in the 'intersticies' of the weldment
(poor weld technique ... not a full penetration weld).

To be 'corrosion resistant' (chlorides, etc. attack stainless) all the
weld must be flat /smooth by grinding and then polishing/buffing to a
high mechanical mirror polish. Any 'weld-lap' or pin-hole in the weld
will be a source of 'rust' .... gotta be closed and then smoothed. .


This has just made sense as only one of the bolt on "feet" for the
ladder suffers from the problem. I'll try it.

Thanks very much to all who responded.

regards
Peter Hendra

A friend has gone thru this with his stainless. People at his workplace
that know about his sort of thing told him he needed to passivate the welds.
They gave him some solution to paint on the welds. I believe this is
hydrofluoric acid, perhaps a mixture with other acids. Requires very
carefull application. It took away the surface shine. Don't recall the
final result but I can ask him.

It won't be Hydrofluoric Acid, which is one of the nastiest nasty
chemicals on the face of this earth. It's much more likely to be a
50~50 mixture of Hydrochloric and Nitric acids plus, sometimes, a
little Phosphoric acid. You should somewhere find an expert and read
http://www.assda.asn.au/asp/index.asp?pgid=17982
Whatever you do, you don't want a strong brew and you should let time
be your friend.



Eric Stevens

Thanks Eric,
A great site and I love your phrase "let time be your friend" -
poetic. May I have your permission to use it in future - yes, I'll
cite you as the originator? I don't want to get flamed.

cheers
Peter

On Mon, 26 Mar 2007 17:56:36 GMT, "Gordon Wedman"
wrote:


"Peter Hendra" wrote in message
.. .
On Sat, 24 Mar 2007 12:44:13 GMT, Rich Hampel
wrote:

Probability is that the welds are not ground flat and smooth and
crevice corrosion is underway in the 'intersticies' of the weldment
(poor weld technique ... not a full penetration weld).

To be 'corrosion resistant' (chlorides, etc. attack stainless) all the
weld must be flat /smooth by grinding and then polishing/buffing to a
high mechanical mirror polish. Any 'weld-lap' or pin-hole in the weld
will be a source of 'rust' .... gotta be closed and then smoothed. .


This has just made sense as only one of the bolt on "feet" for the
ladder suffers from the problem. I'll try it.

Thanks very much to all who responded.

regards
Peter Hendra

A friend has gone thru this with his stainless. People at his workplace
that know about his sort of thing told him he needed to passivate the welds.
They gave him some solution to paint on the welds. I believe this is
hydrofluoric acid, perhaps a mixture with other acids. Requires very
carefull application. It took away the surface shine. Don't recall the
final result but I can ask him.

It won't be Hydrofluoric Acid, which is one of the nastiest nasty
chemicals on the face of this earth. It's much more likely to be a
50~50 mixture of Hydrochloric and Nitric acids plus, sometimes, a
little Phosphoric acid. You should somewhere find an expert and read
http://www.assda.asn.au/asp/index.asp?pgid=17982
Whatever you do, you don't want a strong brew and you should let time
be your friend.



Eric Stevens