3M 5200 as a protective coating

[Morgan Paul]

If you clean the surface and smear 5200 on aluminum or steel would it protect the surface from corrosion and rust? Could it be an acceptable subsitute for paint?

[irwinsailor]

Thats is what I did on every bolt on my mast. I was told to do it by a couple of people in Florida. The few bolt that I have taken lose came lose fine.

[Rick]

There is every reason to expect 5200 to ultimately fail to adhere to almost any metal. This is not a good solution. Ordinary single part spray "epoxy paint" will adhere much better and longer. There are many other superior solutions as well.

Even if the 5200 would adhere (which it will not) it is ugly and expensive compared to almost any other solution.

Originally Posted by irwinsailor

Thats is what I did on every bolt on my mast. I was told to do it by a couple of people in Florida. The few bolt that I have taken lose came lose fine.

Oh my! Someday you might want to talk to a rigger who has to work on masts glued together with 5200. Somebody who know what they are doing, not a "coupleof peoplke in Florida". But you better be prepared for some very unpleasent language!

Seriously, there is no reason for this! The right product is Tef-gel, or if you really need to lock threads in place for unusually sever service, use Loctite.

[David M]

I am totally in agreement with GreatKetch and I have been using Tef-Gel for years. It will stop corrosion because it never dries and never gets washed away. I have an aluminum boat and have threaded stainless into aluminum in many places including places under the waterline. The screws set with Tef-Gel have never seized up or corroded.

TEF-GEL LUBRICANT ANTI- SEIZE ANTI-CORROSION 1 OZ 135591

[Pblais]

For my own opinion I'm in agreement with Rick and GreatKetch. Something that is good at one thing won't cure cancer too. 5200 does one thing well so just live with it. It won't do everything. 5200 still does not stick as well as a barnacle.

[irwinsailor]

I am very happy with the results. The people that told me of this are experts and I have every confidence in their advise.

I also may have misunderstood morgan paul's question.

I am only talking of using 5200 on stainless steel bolts that are used on aluminum to insulate the two metals from each other.

[Stevens 47]

I have purchased Duralac for my refit of my boat. Using it to coat around the heads of the bolts on the new toe rail and other SS to Ali connections. Found the UK maker of the product they have a guy in Canada distributing it for N America. Below is a blurb about it.

Jack

Duralac Jointing Compound DTD 369B
__________________________________________________ ________

…inhibits electrolytic corrosion of dissimilar metals

Description: Duralac is an anti-corrosive jointing compound for use between joints of dissimilar metals.
Form Duralac Jointing Compound is a yellow paste prepared from an elastic varnish medium of low
moisture permeability, a corrosion inhibiting material barium chromate and an inert filler. It
conforms to specification DTD 369B.

Properties: Barium chromate is only very slightly soluble in water and hence is not leached out of the joint
even in the presence of a considerable flow of water. It is however readily decomposed by
acids with the liberation of chromic acid so that it is brought into action only in the presence of
corrosive influences. It is tough and flexible, absorbs little water and is resilient to seawater.

Uses: Duralac is indispensable for the sealing of joints between dissimilar metals of all types
including magnesium and its alloys. It is also valuable for the protection of metals in contact
with wood, synthetic resin compositions, leather, rubber, fabrics etc. When the components
of a structure are of different materials, it is essential that the points or faces of contact should
be treated with corrosion inhibiting materials because in the presence of electrolytes
considerable differences of potential arise, not only where different metals are in contact, but
also where components of the same metal under different stresses are in contact: for
example as between the aluminium alloy plates or extrusions and rivets or bolts used in
building up the structure, in industrial areas where structures are exposed, in flue ducts and
acidic vapours. In close proximity to the sea where a salt laden atmosphere will be met with,
structures will need the maximum attention to prevent corrosion due to the electrolytic cells
set up by the salt laden moisture deposited upon the structure.

Application: Duralac is supplied ready for use and must not be thinned. It is best applied by brush. When
Duralac is applied to metal or other surfaces the volatile solvent evaporates and the
compound sets to the touch, but remains tacky for a considerable period. It is important that
the joint should be closed while Duralac is still tacky – so that it is in such a condition that it
will flow sufficiently under pressure to close the gaps in the joint. It will harden somewhat if a
thin film is left exposed to the atmosphere for a long period and this will prevent the making of
a close joint.

Availability: Duralac is available in the following packaging:
Supplied in 250ml, 500 ml, 1 litre, and 5 litre tins. Also supplied in tubes.
100 Gms/m

2 coverage.

[David M]

Originally Posted by irwinsailor

I am very happy with the results. The people that told me of this are experts and I have every confidence in their advise.

I also may have misunderstood morgan paul's question.

I am only talking of using 5200 on stainless steel bolts that are used on aluminum to insulate the two metals from each other.

5200 wont insulate them. Put a continuity tester across them after you tighten down the bolt and you will have continuity. It will keep the oxygen out for a limited period of time therefore stopping corrosion, which I think is what you are after?

The only way I have found of electrically isolating aluminum from stainless is with nylon, teflon or rubber bushings, gaskets and sleeves.

[hellosailor]

Paul, while 5200 bonds very well to fiberglass and wood, it is erratic on stainless and I'd suspect it on aluminum. I've stainless plates peel right apart when they were bonded with 5200, and that is with degreasing and surgical quality cleanliness before it was applied. I don't know why--but it just didn't hold.

There are protectants designed to protect surfaces. That's not what 5200 is designed for. Almost anything, including plain white canning white or bees wax, will "protect", the question is, how well for how long. Better to use something designed for the job. Anything you put "in between" two metals will be mainly squeezed out when you snug them up, that's why thin plastic washers are used to separate them in demanding applications. And, a protective goop (Lanocote, NeverSeize, whatever) applied on the threads to prevent those from seizing up, mainly because you can't fit a washer in there.[g]

[fstbttms]

A little off topic, but I know of a test being conducted here in California where 3M 5200 is being tried as an anti fouling coating.

[Pblais]

I know of a test being conducted here in California where 3M 5200 is being tried as an anti fouling coating.

Would you happen to know of a list of things that have not been tried as an anti fouling coating? The only thing worse than if it worked would be applying it to my boat.