Thinning Red Lead?

[dmede]

When using red lead to prime joint surfaces such as between a stem and knee or through bolt holes, do you use it straight outta the can or thin it first?

Is it proper to use red lead in a stem to knee joint that will be bed with Sika (or similar)?

thanks
dave

[Andrew Craig-Bennett]

What a magnificent start to what I suspect will be a long running thread!

My two pennyworth:

We are trying to do two, maybe three, things:

1. First, we want to assassinate any decay bacteria or fungi that fancy their chances eating our creation.

2. Second, we want to keep moisture and dirt out of the joint.

3. Third, we want to slow any warping or checking that might be thinking of happening.

From the point of view of I and 3, thin red lead that soaks into the grain is good.

From the pov of 2, thick is good.

So far, we have not considered the drying time of the red lead...

In practice I am of the "slop it on and get on with it" school.

In theory I reckon one should thin it, and then use a conventional bedding compound in the joint (I would not use Sikaflex or 5200 in this application) because the red lead will stop the oil in the bedding compound migrating into the wood.

Now over to those who know what they are talking about!

[Thorne]

I found that I had to thin mine, as it thickened up in the can even when new, got worse over time. Just used Turps for thinner, worked great when thinned just to 'normal' oil paint consistency/thickness.

[dmede]

I'm actually considering bedding with PL weather sealant (black). It's more of a sealant than an adhesive but it sticks pretty good none the less. I was going to use it because I figured that it would be at least as good as traditional bedding with some added adhesion, but be removable for future repairs if needed?

To that end I thought thinned red lead might be better. It would soak in and leave behind a surface that could adhere to the PL better (instead of a thick layer of paint and PL).

[Bob Cleek]

Depends on how good the joint is, I suppose. I would thin the red lead to prime the surfaces. If the joint is really well done, a second application of thicker red lead should serve. If, on the other hand, the joint is not perfect, it might be thickened a bit with some whiting. Bottom line, no amount of goop will make a poor joint into a good joint.

[dmede]

Bob, what's whiting?

Maybe I'm looking for my bedding to do something it shoudln't, provide some backup adhesion to the bolts. The joint is tight, not perfect, but I'm certainly not looking to cover it up with goop.

I'm coming off two smaller boats in which the stem was epoxied to the keel (even on the otherwise traditionally built Fiddlehead canoe). So I can't stop myself form feeling like I need to give the stem & knee assembly as much holding power as I can, besides the 5/16" bolts through assembly and keelson.

Should I be looking to use Dolphinite here instead?

Is there any harm in using Pl weather sealant if it's water proof, flexible, availabe and cheap? What I'm asking is, a joint were you could use only paint can't suffer from a thin application of the PL sealnt instead can it?

[fixmyboat]

roofin' tar :D

[Jay Greer]

Red and White lead are my two favorite "Luting" compounds. Turpentine is also my own choice for thinning most shop made concotions and goos that are used with natural materials.
JG

[Bob Cleek]

Whiting is, I guess, powdered chalk. It's added to white lead (or red) to thicken it up. Add whiting to white lead paste to make white lead putty.

Never expect an adhesive to hold a joint like this, nor even give it any meaningful additional strength. The joint and the fastenings hold it all together. The luting merely keeps moisture out of the joint and provides a bit of stress distribution. Dolphinite is exactly the material to use, if you want to buy something "off the shelf" that is intended for the job. Add some "Di-al" (tributyltin in spirit solution... sold in paint stores to add to paint as a mildewcide) to the Dolphinite if you want "antifungal" Dolphinite like they used to make, but don't anymore. (Econazi's strike again!)

[dmede]

Since were on the subject of bedding I'm going to expand this a bit and ask what would you use in the stem rabbet, between plank and stem?

[dmede]

http://static.flickr.com/95/205418793_64513ec4f4.jpg

http://static.flickr.com/64/205418745_b10ae463af.jpg

[outofthenorm]

I've had good success with thinning red lead with Penetrol (made by Flood, available at your better marine stores) until it's pretty watery. It sinks right into the wood. Then I follow that with a second coat of full strength. I did that the first time I wooded the bottom of Fiddlers Green 20 years ago. When I wooded again a year ago the original coat was still there and holding well under all the old bottom paint and other crap.

As for bedding, there's no question in my mind. If you're using a bedding compound of any kind, slap on the red lead. If you're using an adhesive, bare is better.

- Norm

[JGPierce]

Norm,

Would you consider 3M 5200 a bedding compound or adhesive? :)

I'm getting close to ready to bolt my oak wood keel to my bedlogs and have been following this thread with interest. I've red leaded the other portions of my Haven 12 1/2 and was wondering if I should use it between the keel and bedlogs or just go with the 5200.

Thanks.

John

[dmede]

As for bedding, there's no question in my mind. If you're using a bedding compound of any kind, slap on the red lead. If you're using an adhesive, bare is better.

- Norm

So what about the grey area in which one migth be using an adhesive/sealant as just a sealnt? such as the PL weather sealant? It holds but is primarily a sealant. In this case it's for bedding only but is not oil based like dolphinite.

JG, I defiently consider 3m 5200 (and it's sika equivalent) an adhesive.

[outofthenorm]

John, I'd consider 5200 to be an adhesive, but if you put down the red lead first, it's only sticking to the paint, not the wood. So if you paint first and use 5200, it becomes an effective but pretty expensive bedding compound. Without the paint, it's an adhesive because it's bonding with the wood. How well it sticks to wood that's always wet is a whole nuther topic that's been beat to death elsewhere.

dmede, I look at it this way: if you're using any kind of goop as a bedding compound, then it's main job is to prevent moisture penetration and moisture transfer between pieces of wood. The bedding stuff is acting like a gasket. If you accept that, then a barrier coat of red lead, which is as moisture-proof as paint gets, is the right thing to do, no matter what you use for a compound.

- Norm

[dmede]

Makes sense, thanks norm.

[Charles Burgess]

Back in the old days salt was packed into the interior joints to ensure that whatever moisture that gets it there becomes saline...rot molds don't do well in a saline environment. But salt must be periodically replenished...a tedious process on small vessels with tight work spaces.

Today, we are usually stuck with kilned dried wood. And a lot of vessels are hauled out between time on the water, and thus go through drying cycles that encourages rot molds. For most builders, red lead is the best way to go...first a coat of thin to penetrate, and a thick coat in joints.