AZ3 feet shedding black dust

[Geoff Lister]

I have had my ST120/AZ3 combination for about 2 years. Both have resided in a well-protected, but unheated, extension to my garage. My tripods are supported by hooks and brackets just above head height.

This afternoon, I took down the AZ3, and found my fingers covered in black dust. This came from the tapered surfaces and bases of the 3 black rubber feet, at the bottom of the AZ3's legs. I removed the remaining dust with a cloth, and painted the rubber with varnish, and I hope that this will stop the shedding in future. The dust seemed to be of a graphite/charcoal consistency, and required a lot of soap and water to clean my hands.

I have checked my other tripods and Dobsonian mounts' feet, and most of them have rigid plastic surfaces. However, the Celestron Cosmos WiFi mount's tripod has rigid rubberised feet, similar to those on the AZ3, has been stored in the same environment for about 6 months longer, but does not seem to suffer from the dust-shedding problem. My AZ3 "feature" does not seem obvious in normal use, when I extend or retract the legs; it was only when I touched the feet and got black fingers.

Has anyone else had this problem with Skywatcher/Celestron tripod feet?

Geoff

Edited November 23, 2019 by Geoff Lister
Typo in title

[Carbon Brush]

I have found generally that plastic/synthetic rubber life expectancy is a bit hit and miss. Not just in astro kit.

The rubber tyres on the Skywatcher focus wheels are a good example of degrading rubber. I use O rings instead.

I reckon that less than scrupulous manufactuers (of components not complete equipment) let it out of the door if it is the right colour and texture.
Chemically it may not be up to the job.

The varnish will certainly help bond things together.
It may also delay further degradation by keeping oxygen and moisture off the rubber. But that depends on the varnish.

HTH, David.

[Merlin66]

Not exactly the same problem, but similar Re. plastic life expectancy......

Many of my SkyWatcher plastic fittings have turned "Gold" !!!

I do solar observing, and  can only assume it's due to the UV exposure down here in Australia.

[fozzybear]

Ditto, Same with my Accessories also turning golden colour maybe they want to be like their big brothers WO …….. No it is the UV rays yes we have them here as well perhaps..

Andy

[johninderby]

The aluminium black anodised carry handle on a scope that had been stored on top of a wardrobe turned gold. Also the body of a eyepiece in the finder turned gold as well. The scope never saw sunlight as it only went out at night so not UV. 

[fozzybear]

17 minutes ago, johninderby said:

The aluminium black anodised carry handle on a scope that had been stored on top of a wardrobe turned gold. Also the body of a eyepiece in the finder turned gold as well. The scope never saw sunlight as it only went out at night so not UV. 

what then could it be that is changing the colour as all my kit is stored in a spare bedroom? Gold fairy perhaps... 

[johninderby]

Did some research and found it is probably that the anodised surface has not been sealed properly.

Copper is used in the anodising process and if the surface is not properly sealed the black can turn a bronze colour due to the copper bleeding through the black finish. UV can speed up the process as well.

All my finders have aluminum parts on the front ends so would expect those “gold” parts on the finder are auminium not plastic.

Edited November 24, 2019 by johninderby

[Geoff Lister]

9 hours ago, Carbon Brush said:

It may also delay further degradation by keeping oxygen and moisture off the rubber. But that depends on the varnish.

I used the varnish from a little tube with a brush in the lid; it was part of a 3-tube set, as the clear top coat in a car paintwork scratch repair kit (primer-body colour-protective coat). The rubber feet are fairly stiff, but not rigid, so it will be interesting to see if the "fix" is still working in another 2-years time ⏳.