Question What is the most effective way to clean off old Christo Lube from a environmentally sealed 1st-stage?

[garywong007]

Whenever I am servicing a piston type 1st-stage that is environmentally sealed with Christo Lube, I found it very time consuming and ineffective using paper towels, Q-tips...etc. Even after an ultrasonic bath in heated cleaner and a lot of rinsing, there are always tiny patches of lubes here and there in the crevices. Is there a more efficient and effective way to get this done? I heard about using "base oil" (which I am not sure exactly what it is). I was told by putting the disassembled 1st-stage in a zip-lock bag with enough base oil and then give it an ultrasonic bath, it will come out sparking clean with all old lube dissolved. Is this true?

Rgds,

 

[rsingler]

The recommendation of base oil to remove Christolube is too vague to be of use.

Base Oil Groups Explained

Almost every lubricant used in plants today started off as just a base oil. The base oil category defines what the oil is made of, how it is manufactured, and how the lubricant handles certain environments such as extreme heat.The American Petroleum Institute (API) has categorized base oils into...

www.machinerylubrication.com

Many of these are not oxygen compatible at tank pressure and will require significant removal cleaning in and of themselves.
In industry, both hot alkaline washes (caustic soda) and chromic acid washes are recommended. Neither is safe for the average DIY diver/tech to employ.

But your observation is valid. The residual PTFE is very hard to remove, but the good news is that leaving it there generally does no harm, acting as it were, as a bit of solid lubricant. Still, I agree that Christolube is a problem in this regard. I don't have that problem with Tribolube 71. Tribolube 66 separates a little more easily from its oil carrier, and might be expected to have some if that PTFE deposition.

As for roughing the surface of a piston shaft oring, the recommendation is a clumsy way of reducing friction and o-ring pinch. Much like skidding on a cobblestone curve versus having a rollover in your car on a smooth asphalt curve, you can decrease the total friction by reducing the contact area.
Problem is, it increases wear. Instead, shift to a higher Durometer oring, or satin polish the piston shaft with 4000-6000 grit micromesh, rather than mirror polish to 8000-12000. As dear @Couv taught me, you'll have o-ring pinch with to smooth a surface, unless there's a lubricant reservoir. I do liberally lube the oring and upper shaft of the piston. The half on the ambient chamber side washes away, but some will persist on the top end, and is pushed against the oring by tank pressure when sealing.

It is very difficult to Micromesh a cone seat, and using flat seats with a Mk10 is a throwback in time to poorer max gas flow. The cone seats that still come in sets of 3 with the expensive Scubapro Mk10 service kits are unsurpassed compared to aftermarket versions.

Mk10 service tips?
- Try to find a red spring
- Micromesh the knife edge to sharp and perfect using Micromesh on a pencil, or a Travers abrasive cone, with repeated inspection under a USB microscope during the process.
- Micromesh the piston head land to perfectly smooth with a little square on a fingertip, even if it takes off some chrome
- Use only a double hook pick to remove the HP piston shaft oring. Spearing the oring with a curved pick scratches the land and may create a leak of HP gas from the ambient holes that can't be fixed.

It's a great reg that still performs.