Originally posted by fehknt One additional point that might make you want to re-lube with Helimax -- it's specifically formulated for helicoids on sensitive equipment where "travel" is a problem. Sometimes it's good for a grease to work its way into all the cracks and corners, but on photographic equipment that usually means coating the iris blades/mechanism and making it stick. You may be fine esp in colder temperatures but just a friendly warning about the long-term health applying a grease designed for a different purpose.
Yes, the potential issue of "travel" always should be considered when selecting greases.
Technically, greases are characterized by various properties, including
oil separation and
evaporation loss, amongst others. Lubricants are tested against standards and methods, for example, the ASTM International standards (formerly, American Society for Testing and Materials). Many manufacturers of lubricants publish technical data sheets, which list the results of their tests.
For example, the manufacturer of the Super Lube product line -- Synco -- provides a number of technical bulletins. Generally, they state that their Super Lube synthetic grease with PTFE "offers good mechanical stability, does not evaporate or form gummy deposits. It will not melt or separate. There is no Silicone in Super Lube..."
Similarly, MicroLubrol claims that Helimax-XP "has low seepage so it does not migrate and stays in place better than other [petroleum based] greases that tend to separate, especially at higher temperatures." However, it is not apparent that MicroLubrol publishes technical sheets for Helimax-XP, so it's difficult to compare it technically to other greases.
I'm not trying to promote one grease over another; Helimax-XP has been proven by many users, and it's frequently recommended, while Super Lube is also often mentioned in this context. I think Super Lube is popular because it's commonly available.
It seems to me that Helimax is similar to Super Lube in many respects: synthetic base; PTFE; no silicone; wide operating temperature range; low or negligible evaporation, separation, and seepage; low odor; and suitable for metal-to-metal contact. For larger lenses, the lower viscosity and damping properties of Helimax are probably better suited to helicoid lubrication than generic greases, which are typically not intended for damping applications. For smaller, lighter lenses, a normal synthetic lubricating grease such as Super Lube may be suitable, depending on its viscosity ('stiffness').
- Craig