Weather protecting Screw fixings

Hysteresis · 26 Aug 2019

I am installing some outdoor wall lights. They are aluminium construction with the access cover for Bulb replacement secured by Plated Allen Screws.
From past experience with such lights, I expect the allen screws over time, to corrode and react with the Aluminium casing making it difficult if not impossible for their removal without severe damage to the light casing.
Does any one have Any ideas/suggestions for protecting these screws from the effects of exposure to the elements rendering them impossible to remove?

Burnerman · 26 Aug 2019

Both brass and stainless steel will react to aluminium, so Id be inclined to plaster the screw threads and heads with grease - and not to overtighten them.
You can use red rubber grease if there are weather seals around.
John

Hysteresis · 27 Aug 2019

Thanks for your tip John. My thoughts on Grease are that Over time, grease tends to dry out making screw removal difficult, but of course better than corroded threads. I have never heard of Red Rubber Grease, I will locate a supplier and buy some. Thanks for your advice.
Ian

Harry Bloomfield · 27 Aug 2019

Hysteresis said:
I have never heard of Red Rubber Grease, I will locate a supplier and buy some. Thanks for your advice.

Any car accessory shop will sell rubber grease, it is used behind brake caliper seals, to help prevent steel pistons seizing in alloy bores.

Hysteresis · 27 Aug 2019

Thanks Harry, I appreciate your help, I'll give Halfords a go this afternoon.

Notch7 · 27 Aug 2019

Austenitic stainless steel screws are ok.

Commonly used for the aluminium window trade (I think grade A4 or 316).

Available in small qtys ebay

Hysteresis · 27 Aug 2019

Thanks Notch7, The screws provided by the light suppliers look like they are plated in some material, how would I determine if they are Austenitic SS??.
If they are I could forget all about greasing.
Clearly, Stainless Steel is non Magnetic as is brass, but I have no idea how to identify if the steel or even if these screws are Austenitic steel (they may be brass and without destroying one I can't see what the material is).

Harry Bloomfield · 27 Aug 2019

Hysteresis said:
Clearly, Stainless Steel is non Magnetic as is brass, but I have no idea how to identify if the steel or even if these screws are Austenitic steel (they may be brass and without destroying one I can't see what the material is).

No, the magnetic properties depend upon the particular grade of stainless steel.

Hysteresis · 27 Aug 2019

So are you advising that Autenitic SS is non magnetic?? As I suggested though, Brass is also non Magnetic, so I will still not know if these screws need secondary weather/corrosion protection.

Harry Bloomfield · 27 Aug 2019

Hysteresis said:
So are you advising that Autenitic SS is non magnetic?? As I suggested though, Brass is also non Magnetic, so I will still not know if these screws need secondary weather/corrosion protection.

I have no idea about the autenitic SS, simply pointing out that it is wrong to assume SS is none magnetic, because it depends on the grade of SS.

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Weather protecting Screw fixings

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