I recently grabbed an ordinary red shop rag to wipe down a bathtub with Muriatic acid.
The rag turned blue! (really an intense purple)
When the job was finished and I rinsed the rag, it turned back red!
Do I have a Litmus rag? Just out of curiosity, anybody know what went on?
"HeyBub" wrote in news:Rf2dnZLOu-ZMpNvSnZ2dnUVZ snipped-for-privacy@earthlink.com:
Same principle -- a dye that changes color depending on acidity -- but not litmus. (Litmus is red in acidic solutions, blue in basic.) Various plant dyes could behave this way; Google "pH indicator" for more information.
Red shop rags have a die to react with acid. Most often these rags are used in automotive shops. If you get battery acid on the rag you don't want to use that rag to wipe a smudge off of the floor board carpet or seats.
A follow up to that explanation.
ALSO automotive shops typically use a uniform service to handle the clothing and rag needs in the shop. All of these items are rented and a fee is paid to clean weekly. When the dirty rags are collected to be cleaned they are excluded from the group if nay have the blue spots on them and the shop is billed fro a replacement rag. Tossing a red rag with a blue spot on it in to a group of red rags will contaminate the other rags and they too will show blue spots. SO, automotive shops typically throw away a red rag with blue spots on it.
My brother just had some work done on his car. The bill was detailed, listing number of shop rags used and amount of "kitty litter" used on the floor. Sounded like a hospital bill. Maybe they ARE car doctors.
Damn ... can still learn something new everyday.
Yes, shop rags are treated to show you when they've become contaminated with acid, usually battery acid. It helps the mechanic keep the acid from being passed around to other items. If it turns blue, toss it in the laundry bin.
-- Every day I remind myself that my inner and outer life are based on the labors of other men, living and dead, and that I must exert myself in order to give in the same measure as I have received and am still receiving. -- Albert Einstein
Labor rates are over $100/hr now, sometimes as much as $150/hr.
Everyone's acting like a doctor now. My oral surgeon got $915 for 14 minutes of work, so that's $3,921.43/hr. That's $157k on a good week, or $7,843,860 for a full year of services.
Chiropractors and Veterinarians are easily clearing half a mil a year these days, too.
-- Every day I remind myself that my inner and outer life are based on the labors of other men, living and dead, and that I must exert myself in order to give in the same measure as I have received and am still receiving. -- Albert Einstein
Isn't that something? When I was 18 I thought I knew it all, but here it is 30+ years later and I'm still being humbled by how little I actually DO know. I can't remember exactly when I finally realized I wasn't as smart as I thought I was...
Had no question about that, myself. My Dad, being not too overly concerned with what is known today as "self esteem", reminded me of that on a daily basis! :)
A shop recoups the cost of those type materials like that or charging $3~$4 more per labor hour.
Really? The shop management let the mechanics mix acid contaminated rags with soiled rags? It would be less expensive to throw a rag with blue witness spots away.
It's true that the more one learns, the less one knows.
scott
:-)
------------------------------- The further I go, the behinder I get.
Lew
One of my fave signs was about teens knowing everything. Here's a newer poster:
Yes, unless it was solid blue, it went in with the others at every shop I worked for for about 15 years, per the laundry company's request.
Machinist's rags, with metal shavings/lathe turnings on them went in a separate can, though. Ever wipe your face with one of those? DAMN, it hurts.
-- Good ideas alter the power balance in relationships, that is why good ideas are always initially resisted. Good ideas come with a heavy burden. Which is why so few people have them. So few people can handle it. -- Hugh Macleod
Thanks everybody. I never knew shop rags had an acid marker!
What made this episode more confusing was that the rag had just come out of (my) washing machine!
Anyway, the mystery is now solved. My appreciation to all who contributed. Well done, folks.
It wasn't cleanliness that was the motivating factor; it was trying to find the best way to remove caked-on crud. Had the acid not worked, my backup plan was a single-edged razor blade.
I now have a female living with me and she's absolutely anal about things being tidy. She even insists on washing coffee cups between uses.
Why, I have no idea.
ROTFL, per the laundry company's request! They were the ones selling replacement rags, right?
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