Watch cleaning lighter fluid

[mikepilk]

3 minutes ago, nickelsilver said:

CAS for the benzine that everyone uses for watchmaking purposes in Switzerland is 64742-49-0. "Naphtha (petroleum), hydrotreated light"

That's the stuff I use. It also has "SBP3" after the CAS.

I use it to do a quick ultrasonic pre-wash on really dirty movements, for cleaning watch bracelets, and hand washing mainsprings (can't figure out how to hold them to clean in the ultrasonic)

[Neverenoughwatches]

Anyone know what this benzine grade spec means ?

[RichardHarris123]

Specific gravity, an old unit of density. The Specific gravity of water is 1 so the benzene is less dense. 

[Neverenoughwatches]

56 minutes ago, RichardHarris123 said:

Specific gravity, an old unit of density. The Specific gravity of water is 1 so the benzene is less dense. 

I thought the modern water density measurement is 1 tonne per cubic metre.?

3 minutes ago, Neverenoughwatches said:

I thought the modern water density measurement is 1 tonne per cubic metre.?

Sp. gr. ?  Something per gram ?

[RichardHarris123]

Specific gravity is now called relative density.  Set water at 1 and compare solids and liquids to it. The density if brass is appropriately 8500 kg/m³ so it's relative density is 8.5 etc. Gasses are compared to air, air equals 1.

[htodd]

I have a degree in chemistry and words like "naphtha" and "ligroin" would cause us fits in school when we were trying to figure out what they were. We used them in organic chemistry as solvents. Most things in organic chemistry are named so clearly that you would know exactly what atoms were in the compound and often how the atoms were oriented.

In any case, it's my understanding that naphtha and ligroin are created by fractional distillation of petroleum. You get molecules with a specific range of carbon atoms in the distillate, and then you desulphur the distillate. The name comes from people who are making industrial fuels and solvents and are chemical engineers and not "chemists" and so the terms are a little more squishy. And historic.

That's just the perspective of someone who had to deal with those solvents in chemistry lab.

I liked reading through this and wondered how to see if my solvent was too dirty. I don't want to switch it out for every watch, especially since I'm working on broken watches from ebay. Just putting a drop on a mirror is much easier than the optical scattering device I was thinking of building.

I really need to find a real watch cleaner though.

[RichardHarris123]

I laughed at your comment because I am a Chemical Engineer and you comments are correct.  My chemistry is good compared to the general population but poor compared to a chemist. We basically let you do the chemistry and scale it up.  

[CYCLOPS]

here is some more info, I use to get them confused....

 

https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.echemi.com/cms/1509988.html&ved=2ahUKEwjT1fK9k4yJAxWj78kDHaVmLmAQFnoECDEQAQ&usg=AOvVaw2b9UexI_BDDiFLY8iRYwny