The RSJs holding up my upper storey have been exposed as part of
building work. They have slight surface rust (I'd say powdery 0.5mm
after 70 years) (web is 10mm thick) Not really going to affect load
bearing capacity, but it may be work painting them with something.
Hopefully wont need to clean them to fresh steel - that would be a
horrid job.
What should I slap on them to stabilize the surface ?
Cheers,
Simon.

On Thu, 13 Aug 2009 09:30:55 -0700 (PDT), sm_jamieson
wrote:

The RSJs holding up my upper storey have been exposed as part of
building work. They have slight surface rust (I'd say powdery 0.5mm
after 70 years) (web is 10mm thick) Not really going to affect load
bearing capacity, but it may be work painting them with something.
Hopefully wont need to clean them to fresh steel - that would be a
horrid job.
What should I slap on them to stabilize the surface ?
Cheers,
Simon.

I've used Hammerite No1 Rust Beater on a couple of cars and not bothered with
any further coats - though is both a primer and undercoat - and it has remained
in excellent condition, with no further rusting. I wouldn't hesitate to use it
in your situation, as it can be applied directly to rusty metal.

Andy C

sm_jamieson wrote:
The RSJs holding up my upper storey have been exposed as part of
building work. They have slight surface rust (I'd say powdery 0.5mm
after 70 years) (web is 10mm thick) Not really going to affect load
bearing capacity, but it may be work painting them with something.
Hopefully wont need to clean them to fresh steel - that would be a
horrid job.
What should I slap on them to stabilize the surface ?

Many rust removers are simply acids. This stuff converts rust into an inert
black layer
http://www.amazon.co.uk/Loctite-Rust.../dp/B0001P0DLK


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

On Thu, 13 Aug 2009 09:30:55 -0700 (PDT), sm_jamieson wrote:

What should I slap on them to stabilize the surface ?

I've used Kurust (another Hammerite product) to good effect. Converts
the rust to phosphates I think. Certainly stopped rust on bits of car
and on rusting corner reinforcement in plaster. The last bits on a
car have not been painted over and have stopped rusting.

http://www.hammerite.com/uk/products/ps_kurust.html
http://www.hammerite.com/uk/products...st_beater.html

--
Cheers
Dave.

sm_jamieson wrote:
The RSJs holding up my upper storey have been exposed as part of
building work. They have slight surface rust (I'd say powdery 0.5mm
after 70 years) (web is 10mm thick) Not really going to affect load
bearing capacity, but it may be work painting them with something.
Hopefully wont need to clean them to fresh steel - that would be a
horrid job.
What should I slap on them to stabilize the surface ?
Cheers,
Simon.

Just use red oxide primer like the steel suppliers do.

http://www.screwfix.com/prods/13032/...rimer-1Ltr-Red

http://www.decoratingdirect.co.uk/viewprod/t/TORQDRO/

In message , The Medway
Handyman writes
Many rust removers are simply acids. This stuff converts rust into an
inert black layer
http://www.amazon.co.uk/Loctite-Rust-Remedy-Bottle-88781006/dp/B0001P0DLK
I think Wilkinsons chain stores sell this - at least that's where I
bought it from at a better price than that quoted. My local friendly
small garage recommended it. I've painted it on, but it's too early to
say about results.
--
Bill

"Dave Osborne" wrote in message
...

Just use red oxide primer like the steel suppliers do.


I don't have any of the product but...AFAIK...
The active ingredient of the paint formerly used for rust protection of
steel was lead oxide and because the oxide of lead is red in colour the
product was called red oxide paint. You would know a tin of real lead
oxide paint because it is extreemly heavy compared to a similar sized tin of
ordinary paint. However I think the sale of real lead oxide paint has been
banned for many years because of the toxicity of lead oxide.

The safety data sheet on the product you listed doesn't mention lead at all,
so i take it there is no lead oxide in it, and the word lead doesn't appear
in the phrase 'Red Oxide Primer'.

Perhaps someone knows what the active rust protecting ingredient is?

Roger R

Roger R wrote:
"Dave Osborne" wrote in message
...

Just use red oxide primer like the steel suppliers do.


I don't have any of the product but...AFAIK...
The active ingredient of the paint formerly used for rust protection
of steel was lead oxide and because the oxide of lead is red in
colour the product was called red oxide paint. You would know a
tin of real lead oxide paint because it is extreemly heavy compared
to a similar sized tin of ordinary paint. However I think the sale
of real lead oxide paint has been banned for many years because of
the toxicity of lead oxide.
The safety data sheet on the product you listed doesn't mention lead
at all, so i take it there is no lead oxide in it, and the word lead
doesn't appear in the phrase 'Red Oxide Primer'.

Perhaps someone knows what the active rust protecting ingredient is?


Trimite Red Lead - now that takes me back a few years. It was used in a BS
standard for measuring the surface area of odd shaped articles. Weigh the
article dry (having been heated to 105C IIRC, dunk in the paint, allow to
drain and dry and then re-weigh. Then calculate the surface area based upon
the paint taken up.

I've still got some of the samples I dunked in 1974/5 in a bedroom upstairs.
Now I'm in a morose state. No wonder my children are stupid. What should I
do with these samples? Can I legally dispose of them. Have I committed a
crime retaining these samples? Answers, please!

Seriously, in answer to the OP, is there a need to paint the RSJ? If it will
not feature in the habitable space and will be in a dry concealed location,
why paint it?

If after 50yrs+ there is just a dusting of rust, forget about it...
- Black rust is millscale and actually inhibits further rusting
- Paints like hammerite can trap moisture if cracked (unlikely on an
RSJ)
- POR is good, but forget welding to it, or mag-drill n bolt to it
either
- Rust converters work, but only to a very limited depth
- Red Oxide does not have lead, probably some other oxide

Typically if you want to protect structural steel you...
- a) 3M Clean-n-Strip disc to a shiny surface including pits
- b) media blast to a "sa2" bright shiny surface including pits
- Paint with zinc epoxy primer £50 or epoxy mastic £30

To touch up coated steel, use galvafroid...
- Real cold zinc primer, £15 for 250ml, extremely heavy
- Only works where zinc can directly contact steel not rust
- No abrasion resistance, but very effective

I'd rather put the money towards replacing guttering early, because
that can really leave a trail of problems.

On 15 Aug, 00:04, "js.b1" wrote:
If after 50yrs+ there is just a dusting of rust, forget about it...
- Black rust is millscale and actually inhibits further rusting
- Paints like hammerite can trap moisture if cracked (unlikely on an
RSJ)
- POR is good, but forget welding to it, or mag-drill n bolt to it
either
- Rust converters work, but only to a very limited depth
- Red Oxide does not have lead, probably some other oxide

Typically if you want to protect structural steel you...
- a) 3M Clean-n-Strip disc to a shiny surface including pits
- b) media blast to a "sa2" bright shiny surface including pits
- Paint with zinc epoxy primer £50 or epoxy mastic £30

To touch up coated steel, use galvafroid...
- Real cold zinc primer, £15 for 250ml, extremely heavy
- Only works where zinc can directly contact steel not rust
- No abrasion resistance, but very effective

I'd rather put the money towards replacing guttering early, because
that can really leave a trail of problems.

Well I'll probably just leave it then. I'll just hoover up the small
amount of
loose dust on the flanges. I've just replaced the guttering as it
happens ... ;-)
Simon.

On Aug 15, 9:51*am, Simon wrote:
I've just replaced the guttering as it happens ... ;-)

Well done, avoids you finding all those outer-to-inner-leaf water
paths! :-)

Anyone doing guttering on an old house:
- Check the felt into the guttering, it is often rotted
- So slip DPC under the bottom row of tiles carefully

That can stop wind blown water migrating toward rafters, soffits,
bedroom ceilings, wallplate, cavity.

Something to remember if you ever get a tower up for other jobs, saves
about 1k. Almost worth buying a tower for (assuming you can handle
heights which I can't... well I can... it's just I impersonate an
incontinent seagull the higher I go). "You have some big birds in this
area"... "that is not the birds".