what to do where steel bolt meets aluminum housing

Hi everyone,

My Aquatica housing has a large steel bolt that goes directly into the raw aluminum housing, to hold each handle in place.  Should I coat these steel screws with anything before I replace them?  Is this something I should be doing on long trips, or just once a year?

Obviously I am concerned about galvanic corrosion.

Thanks

I just noticed a little bit of white sticky grease on the bolts - what would that be?  Is that lithium grease?

1 hour ago, rwb500 said:

I just noticed a little bit of white sticky grease on the bolts - what would that be?  Is that lithium grease?

Yep, it's to help you be able to undo it when the need arises. Don't clean it off.

The best antioxidant/corrision 'stuff' to use for stainless to aluminum is "Lanocote" and available usually at marine supply stores and online. A little goes a long way so although it's a bit expensive you'll have a lifetime supply and then some.  It's brown and slightly stinky...

My Aquatica manual for A7RIII housing is quite clear on the maintenance of handles, here is the text; 

"Periodically remove the hand grips for storage and transportation to avoid having the thread of the attachment bolts fuse on to the housing. Unscrew, clean and lubricate the bolts with a small amount of WD-40 or Zinc-based lubricant."

I use 5/16" stainless steel cap screws for my Aquatica housing handles. I coat them with a light layer of silicone and remove the handles and cap screws after each trip. Never had a problem with corrosion. Make sure that the sacrificial anodes in the bottom of the housing are in good shape.

The white sticky compound is likely an anti-galvanic corrosion zinc jointing paste such as Tefgel rather than straightforward grease. A similar zinc jointing paste that is yellow is Duralac. These are very commonly used in saltwater environments, for example on aluminium boats, outboard engines or yacht masts where stainless steel fasteners go into aluminium. It's still important to undo the fastening now and again and redo to avoid any aluminium oxide build-up causing seizing. 

You could replace them with Nylon bolts.

I used to be a design engineer in the aluminium ship building industry.  The solution used for this problem was to use Duralac jointing compound or Tef-Gel corrosion eliminator.  Tef-Gel is what I've used on my housing handle bolts (Subal and Nauticam) for many years and I've never had a problem with corrosion/siezing of bolts.  Before that I used silicon grease and it worked well too.

You want Tefgel for that. I have also used Super Lube for that purpose and it works just fine. I always remove the handles and any stainless bolts that go into the aluminum housing, rinse, dry and apply Super Lube or Tefgel before storing a housing. An important part of maintaining your housing, if  you ask me.
 

20 hours ago, rwb500 said:

Hi everyone,

 

My Aquatica housing has a large steel bolt that goes directly into the raw aluminum housing, to hold each handle in place.  Should I coat these steel screws with anything before I replace them?  Is this something I should be doing on long trips, or just once a year?

Obviously I am concerned about galvanic corrosion.

 

Thanks

Hi rbw 500

What camera model housing do you have?

The screws used to attach the handles to our housings are made of Stainless Steel.

They do not screw directly into the aluminum housing, all our housings have Stainless Steel Heli coil inserts at the grip mounting point location.

A Zinc O lube product can be used on the end of each screw, but the best maintenance is to remove the grips as much as possible and if you notice a small buildup of salt crystals these can be removed with fresh water and a  soft tooth brush.

Good maintenance goes a long way.

Hope this helps

These posts reminded me that, since arriving almost two years ago in Sint Maarten (and diving 3-4 times a week), I have never unscrewed the stainless steel bolts that hold the handles on to my Subal housing.

Happily, just having done it now, they unscrewed easily ( had given them a coat of silicone grease when screwing them in when I arrived) and looked clean as a whistle.

A quick coat of silicon grease and they're back in place..... 

Carolina's point about removing any small salt built-up with a toothbrush and hot water is a good one. I've also used a toothbrush with diluted (50:50) white vinegar. That works well too. 

11 hours ago, Carolina A. said:

Hi rbw 500

What camera model housing do you have?

The screws used to attach the handles to our housings are made of Stainless Steel.

They do not screw directly into the aluminum housing, all our housings have Stainless Steel Heli coil inserts at the grip mounting point location.

A Zinc O lube product can be used on the end of each screw, but the best maintenance is to remove the grips as much as possible and if you notice a small buildup of salt crystals these can be removed with fresh water and a  soft tooth brush.

Good maintenance goes a long way.

Hope this helps

Thanks! I have the AD810.  I guess I didn't look carefully, or maybe the chalky salt crystals hid the helicoil from me.