CST to weight charts for silicon oils.

[Dan B.]

I posted some incorrect information in another thread that I corrected, so I wanted to post this here. I’m sure it’s been covered before, but maybe not in this way. Apparently different brands seem to arbitrarily assign “weights” to their silicon fluid and they differ greatly. I had no idea there was this much deviation by brand. There appears to be no standard in the RC community for converting CST to Weight.
https://rsrc.biz/en/blog/cst-to-wt-silicone-oil-charts-n90

 

[Hector_Fisher]

I've always found this to be utter nonsense. Its like the manufacturers feel the need to differ in the way they describe their own special product... How hard is it to use something actually universally recognized and comparable like fluid density?

Or am I just being dense about this?

 

[Diem Turner]

Isn't it something to do with the fact that, due to its nature, the oil viscosity standards measured in CST and Wt. can't be applied to silicone in the same way making any measurements taken this way quasi meaningless? It's like trying to measure air temperature with the tachometer in your car If memory serves, silicone fluids' viscosity is actually measured in cps or something like that.

 

[CosmoM3]

I use that same chart as well.

Team Associated silicone oils seem to be the most accurate IMO.

 

[Diem Turner]

I've always found this to be utter nonsense. Its like the manufacturers feel the need to differ in the way they describe their own special product... How hard is it to use something actually universally recognized and comparable like fluid density?

Or am I just being dense about this?

Maximum molecular density achieved, your honor. I know what you mean, although I don't think that fluid density is a reliable indicator of or yardstick, if you will, that relates to its viscosity. But viscosity values do exist specifically for silicone based products. I get the sneaking suspicion that the manufacturers didn't want to weird people out and just decided to slap a characteristic people were familiar with but fails to accurately represent the true viscosity of a silicone based oil. Just speculating here.

 

[Dan B.]

Isn't it something to do with the fact that, due to its nature, the oil viscosity standards measured in CST and Wt. can't be applied to silicone in the same way making any measurements taken this way quasi meaningless? It's like trying to measure air temperature with the tachometer in your car If memory serves, silicone fluids' viscosity is actually measured in cps or something like that.

Good question. That website suggests that CST ratings would conceivably be a standard, even in silicon. Or am I interpreting this wrongly? From the website:

“The viscosities of oils measured in cSt (centistokes or cP centiPoise) correspond to the universal unit of measurement, measuring the resistance to deformation of a liquid. For example, water at 20°C has a viscosity of about 1cSt.
In contrast, oils measured in WT correspond to a weight.
While the cSt measurement should vary very little from one brand to another, the WT value may be further away”

I’m not really certain, it’s a little ambiguous.

 

[Diem Turner]

Good question. That website suggests that CST ratings would conceivably be a standard, even in silicon. Or am I interpreting this wrongly? From the website:

“The viscosities of oils measured in cSt (centistokes or cP centiPoise) correspond to the universal unit of measurement, measuring the resistance to deformation of a liquid. For example, water at 20°C has a viscosity of about 1cSt.
In contrast, oils measured in WT correspond to a weight.
While the cSt measurement should vary very little from one brand to another, the WT value may be further away”

I’m not really certain, it’s a little ambiguous.

I might be wrong but I think I remember reading somewhere that silicone is a Newtonian fluid and while I know the square root of Jack sh!t about what exactly that means in this particular context, my gut instinct is telling me that the way one measures the viscosity of non-Newtonian fluids is different. I have bupkis to back this up in any way, that's just my stomach firing on three cylinders.