Caulking

[roh]

Hi

Any advice, I need to recaulk this winter and have so far stripped out all the old red lead and cotton and am going to replace with the same, although not all the seams have cotton as a majority are very tight fitting so only had lead payed into the seams. Do I need to prime the seams with anything prior to paying in the red lead ??

Does anyone have any additional tips on the best way to ensure that the red lead is tight in the seams and all the air is expelled.

 

[MacW]

Long time since I`ve done this job, but I would say you need to get SOME cotton in the seams, even if only a thread. Proper caulking irons will slightly prise open the seam ahead of your thread, working along the seam from end to end. I seem to remember one should start at the top seam and work down towards the keel. Again working along the seam, once all the cotton is in place, force in the red/white lead using the flat of a spatula,scraper etc. Tends to be messy and liberally decorate adjacent planks but if you are painting afterwards, no matter. Different story if varnished hull. Lead putty should last 20 years plus. More modern ( and more expensive ) stuff like `Lifecaulk` may last longer, but problems getting it to stick to oily woods or seams previously caulked with lead.
Hope this helps.
Pete.

 

[Mirelle]

Just so. Prime the seams with paint first (otherwise the linseed oil will leach out of the putty into the wood). Use white lead putty for topsides, red lead putty below.

You need cotton everywhere, but if the seam is tight just get a thin strand in.

Good explanation in Michael Verney's "Complete Amateur Boat Building".

 

[Porthandbuoy]

Agree (mostly) with Mirelle. You can use red lead putty above the waterline as it doesn't leach through modern paint. As far as I know that was the only reason for using white in the past.

The cotton isn't just there to help keep the water out. It gives the wood something to bear down on as it gets wet and expands (the wood, not the cotton). This helps to stiffen up the whole structure.

If your boats been out of the water for a long time don't put too much caulking in too hard; you need to leave a bit of 'give' for the wood to expand. otherwise cracked frames or broken fastening will result.

I completely recaulked Mariposa last summer after she'd been out of the water for several years. I'll be hauling her out next month to harden up the caulking where I've got a bit of water seeping through (and one persistent drip after I took her out in a hooly in January!). FYI she took months to take up fully.

Start at the top as Mirelle suggests. IMHO the reason for this is you will be much more proficient by the time you reach the garboards!

 

[Mirelle]

OK, I'm a coward!

If, after she goes back in, all the seams squeeze their stopping out into a gentle convex shape, you've got it about right. Scrape the excess off when you next paint the topsides.

Don't, whatever you do, bash the cotton right through the seam.

 

[mrswigglestick]

I don't know much about caulking so am eager to learn- Mirelle, I'm interested in what you say about the seams squeezing their stopping into a gentle convex. I gathered in my square rig days that the idea was to put the stopping in with a gentle concave, so that (if the caulker got it right) the seam squeezed it almost flush with the surface of the planking. That was big ship stuff involving several strands of oakum and a biumen-based stopping (which is the only bit I was allowed to do...) so is it better to do it your way with little boats?

 

[tillergirl]

"You can use red lead putty above the waterline as it doesn't leach through modern paint. As far as I know that was the only reason for using white in the past"

Really? You clearly aren't using a modern paint by a well known marine paint company!

Sorry I couldn't resist being ironic.... I'm afraid I did get leaching and show-through.

 

[Porthandbuoy]

You're correct in one respect. I didn't use a modern paint by a well known paint company. I used Dulux Exterior Gloss; two coats on top of two undercoats on top of three of metallic pink primer (and bit of Primocon 'cos I run out of MPP).
I was going to use Trade Gloss from Homebase, but I thought "What the hell. Hang the expense."

 

[Mirelle]

Well, it's simpler. I don't know how you would judge the precise degree of "concavity"! And the boat looks tidy as she goes into the water and you take the "end of the job at last" photos!

 

[PeteCooper]

http://www.boreme.com/boreme/funny-2006/caulking-p1.php

Sorry - couldn't resist - Note : a bit rude !

 

[skipperscouse]

Hi
I always use oakum for wider seams, lovely smell too !
Also I've found that a traditional caulking mallet is much easier to use than anything else I've tried, Once you get into the ''swing '' of it, the varying tone is handy too , you tune your ear to the tone as it changes according to resistance,helps too get seams more aqually caulked, I'ts worth persevering with to get used to it.
I've just started preparing ready for re cauking again,
good luck.
also thanks for all of the replys I received. Very interesting.