Red Lead -why?

[Seagreen]

As I'm mixing this putty up, I think "what does the red lead do?"
So, what does it do, in the putty? Why put it in at all, and what's the difference between red and white lead?

 

[Seanick]

One adds red lead 'cause thats what you do!

It helps prevent crumbling, adds a little flexibility, and preseves.

Stop up a little length of seam without it and compare the result in a few years.

White lead used to be used to stop up the topsides, and red below the waterline. With the older linseed oil paints red lead putty would leach through and show. With Alkyd paints this does not seem to happen. Weather one is better than the other I don't know!

 

[Bajansailor]

On the same theme, here is another red lead question.

I have noticed that folk up your way prime their hull timbers with red lead paint. I presume that this helps to preserve them against all the nasties like rot and such? Red lead seems to be pretty poisonous stuff, so it should logically be quite good at this....

On timber fishing boats here, everybody paints the timbers, keel, floors, everything on the inside in fact, with ordinary marine enamel paint (usually grey by choice) without any primer.
I am sure that red lead would be infinitely better for this purpose, and I have tried to tell boat owners and builders that, but tradition has that they have always done it this way.

Also, when fastening two sections of timber together - it could be a frame to a floor, or a hull plank to a frame - the builders here never use any bedding compound.
Even on exterior timber like when rubbing strakes are secured to the hull midway between the waterline and the sheerline.
It seems fairly obvious to me that this must be the reason why the hull timber behind the rubbing strake tends to rot, yet the Builders do not agree.

Seanick, what is your favourite recipe for bedding timber with?

And the Builders here are adamant that butting planks onto frames is a much better method than using butt blocks between the frames. While I have seen some boats that look a bit like parquet floors because they have so many short sections of hull planking added to replace areas of rotten (or worm eaten) wood.

And I wont start ranting about using WEST epoxy with mahogany sawdust as stopping over the cotton caulking between the planks.....
(always lots of mahogany sawdust around, as the hull frames are invariably sawn mahogany)

A friend of mine cynically (realistically?) suggests that the Builders are ensuring that they do not do themselves out of future work by adopting such practices and techniques as mentioned above.
I would be interested in your thoughts re the above.

 

[misty56]

White lead is hydrated lead carbonate and red lead is lead tetroxide. These salts are insoluble or nearly so in water but both are soluble in acids, eg stomach acid, and therefore MUST NOT be ingested either orally or by breathing in the powder. However if handled intelligently in accordance with the MSDS they are safe.

In use as undercoating paint, the difference is effectively just the colour-- red lead for dark topcoats, white lead for pale.

Lead-based paints are effective rust-proofers as well as rot-proofers. In fact I wonder whether, if lead paints were not hazardous in many applications, modern chelating paints would have been devised at all.....

Bajansailor, that bit about stopping with epoxy+sawdust is what I'd call a nightmare scenario!

 

[cliffordpope]

I have read that red lead has the almost unique property of bonding to wood like no other paint. I certainly remember in pre-H & S days helping my father blowlamp old paint off doors and window frames that you could get all the paint off except the primer, which stubbornly refused to shift. Red-lead primed wood was forever red underneath.

 

[misty56]

That is true. It's why red lead got used for the more exposed jobs, where the paint had to last a long time. Round here on the big country estates they'd go through gallons of red lead and each estate would have its own "estate colour" for the topcoat, usually maroon, green, brown or blue, and every stick of wood would get the both-- the painters were usually on the estate staff and they just started at one end and worked through to the other.

 

[Seanick]

A college we were taught to 'lute all faying surfaces with white lead paste'. All varnished trims should be primed behind before fitting to prevent water ingress and future discoloration.

We now prime with aluminium wood primer and bed on Butyl rubber (Arbomast BR). Red lead paint may be better but I wish to live as long as possible......

Butting planks on to frames is simply quicker and cheaper. No butt strap to make. In the long term the first method tends to split the frame into two, and its usually too many fastenings for that area of frame. On my '33 Scotish fishing boat the planks were spiked on to the frames, but where butted the adjacent frame had a through iron rivet as a bit of insurance against the butts popping....
In most areas I have now used long glued scarphs or butt straps with bolts.

Your builders either can't be arsed to change or don't care about longevity when faced with the economics of building the boat as quickly as possible. Its much more pleasant to assemble stuff without paint and goo squeezing out, and so much quicker.


The problem with epoxy and sawdust is that it goes hard instantly. Red lead putty goes hard eventually, but usually after the boat has been launched and has settled down. It then adds to the structure by creating more friction between the planks and creating a monocoque structure. If the boat dreis out it need soft putty put in again to allow the process to start again.

 

[misty56]

[ QUOTE ]
Red lead paint may be better but I wish to live as long as possible......



[/ QUOTE ]

I don't want to disagree but--neither red lead or white lead are dangerous IF HANDLED PROPERLY IN ACCORDANCE WITH THE MSDS.

For the amateur, who is probably scared witless by all the hype anyway, and who very carefully uses the stuff once or twice a year, the risk is really minimal.

Remember: it is principally ingestion, either by swallowing the paint or breathing in the dust that is dangerous with these lead salts.

I'm not saying everyone should give up the modern alternatives and go back to lead, if only because the lead is pretty costly these days. I am saying that if you have a classic wooden boat that originally had lead paint and you want to replace it, that will be okay as long as you read and understand the risks and the methods needed to protect you-- which in this case is good coveralls, impermeable gloves, a particle mask and safety glasses. (And, dare I say it, some common sense.)


I actually think getting the stuff off is much more dangerous than getting it on-- never sand lead paint down, you know that dust you get? It's poisonous........

..

 

[Seanick]

Re saftey, I agree with the above, but I would be using it almost every day. I just don't want to join the 'trad boatbuilders dont live very long gang'. I wonder how many times have people remarked on how well it may have preserved this boat or that, then though about John the original builder who died the day after he retired......

 

[Seagreen]

A Particle mask.

OK, I'll get one of those, then. Bit more assured than holding my breath.

/forums/images/graemlins/laugh.gif

 

[Woodlouse]

We've all done it though haven't we... /forums/images/graemlins/tongue.gif

 

[misty56]

No argument there. Professional use of any toxic chemical is always more hazardous because of the repeated exposure to relatively higher doses. Plus IMO there's a big difference between what I'll do for pay and what I'll do for love-- in other words I would use lead on my own job but not on someone else's.