What's so special about the hot sand?

January 15, 2008 10:48 AM

What's so special about the hot sand that opticians use? Do I need this to make adjustments to my glasses frames?

Okay, so I bought some cheap frames from Zenni. I like them a lot, and the fit is pretty good, but not exact. Every time I've had glasses adjusted at the opticians, they've always dipped them in the hot sand pit first. Do I need that? Can I just bend them (they're regular metal frames, not titanium)? Should I not try to do this myself?

posted by Caviar to clothing, beauty, & fashion (22 comments total)

I think they do it because hot sand makes the frame easier to bend (less breaking risk) and it doesn't stain the metal as a flame would do.
posted by Memo at 10:52 AM on January 15, 2008

(As an aside: I am so glad you posted this, because despite having worn glasses for almost all my life, I have never seen them do this, and I had no idea what they were doing when they ducked into the back to make an adjustment. So, thanks!)
posted by fiercecupcake at 10:56 AM on January 15, 2008

Memo is correct. The hot sand makes the frame more pliable. It's safer to get your glasses adjusted by an optician, but if you absolutely must do it yourself, warm them with a warm washcloth first, or even with the friction of your fingers if nothing else is available. Don't bend them while they're cold (especially if they're plastic).
posted by amyms at 11:11 AM on January 15, 2008

It's a gentle and efficient way to heat the frames evenly. Make your own -- get some sand from a craft store and nuke it.
posted by desuetude at 11:13 AM on January 15, 2008

How necessary is it? Is there any other way to replicate the (presumably) even heat? If I wanted to buy one of those, what is it called? What temperature does it heat to?
posted by Caviar at 11:16 AM on January 15, 2008

The guy at Old Focals suggested using a blowdryer to accomplish this at home.
posted by chez shoes at 11:17 AM on January 15, 2008

If I wanted to buy one of those, what is it called?

At the optometrist's office I worked for, we just called it the "sand tray," but ours was homemade (just an electric skillet set on "warm" filled with tiny silicone beads).
posted by amyms at 11:18 AM on January 15, 2008

P.S. And, as I said above, it's not absolutely necessary. I regularly adjust my own glasses and my daughter's glasses at home without the use of the sand tray, but I make sure I warm the frame first with a warm washcloth.
posted by amyms at 11:19 AM on January 15, 2008

I just run mine under fairly hot but not hottest water before I adjust them.
posted by jacquilynne at 11:24 AM on January 15, 2008

With lenses in them yes? It would prevent the glass from shattering and create an ease of movement throughout the entire thing (glass, metal whatever). Also a flame is precise where the sand would act more like a kiln which is just far more even.

I didn't know they did that either, so depending on how much bending you want to do? And how hot that sand actually is, maybe hot/boiling water will do the trick? (Only an expert 'coz I paid the $5. The advice was free, but you still get what you pay for.)
posted by mu~ha~ha~ha~har at 11:25 AM on January 15, 2008

The two optometrists in my family use salt, not sand. It looks a lot like sand, though. (Does heat darken salt? I hope it's not dirt causing the sandy color.) Here's a source for salt pans. I'm told that a lot of eyeglass dispensaries use hot air to warm frames; that might be more convenient at home.
posted by wryly at 11:28 AM on January 15, 2008

Be careful about using heat on plastic lenses, particularly boiling water as someone speculated above. I once boiled a throwaway pair of glasses with black plastic frames to "super clean" them, and they quickly discolored horribly. One of the reasons opticians use sand is that it's a fairly low-intensity, uniform, well-regulated source of heat. Neither fire nor water has these virtues.
posted by stupidsexyFlanders at 11:41 AM on January 15, 2008

There's also always the hair dryer. Just be careful not to succumb to the temptation to get them blistering hot and super-pliable - you just want a little warm.
posted by phearlez at 11:51 AM on January 15, 2008

And if you have one of the super-thinned lens options be even more careful. I was told to not let anyone adjust my glasses in the hot sand.
posted by mikepop at 11:51 AM on January 15, 2008

I was in the same pickle, and I took my glasses to my neighbourhood opto (with whom i had no prior relationship) and she adjusted them free of charge.
posted by sid at 12:16 PM on January 15, 2008

My optometrist told me a few days ago that they switched from hot salt to hot sand because salt had some negative effects on newer type frames.
posted by niccolo at 12:51 PM on January 15, 2008

I had the same experience as sid. I got cheapo frames from zenni and swung by the optometrist at CostCo and they adjusted my frames for free in about 5 minutes (without even bothering with hot sand or heat of any kind, either).
posted by maniactown at 1:06 PM on January 15, 2008

I work at an optician, its just to warm the plastic parts of the frame like the tips that go over your ears. When adjusting glasses at work I always heat them although its not normally necessary on a metal frame. You could use a hairdryer to achieve the same effect. As mentioned above most opticians will adjust your frame for you for free and it will only take a minute or two.
posted by john_son at 2:20 PM on January 15, 2008

hmm... I have a web-purchased pair as well (optical4less.com) and the center seems way too flexible to be bent. I'd love to be able to tighten them a bit to make the fit perfect. I'll try Costco. Any eyeglass folks have any experience with the silly-super-ultraflexible metal frames?
posted by bakertim at 3:13 PM on January 15, 2008

its just to warm the plastic parts of the frame like the tips that go over your ears.

Yeah, in my experience they don't use the sand for metal frames.
posted by Rash at 5:11 PM on January 15, 2008

I had no idea they did this and have been making small adjustments to my own (metal, or plastic, with metal wire inside for support) frames by hand for several years. I've never broken a pair doing this.
posted by !Jim at 8:29 PM on January 15, 2008

bakertim: The center of flexible frame will be difficult to adjust yourself but not impossible, you can either hold it in position until it retains the shape you want (this will not always work and can take a long time) or you'll have to heat the bridge until it is hot (very hot) and hold the frame in position until it cools (if your lenses have an anti reflection coating on them you'll want to remove them 1st). Most opticians should be able to do this for you.
posted by john_son at 4:17 AM on January 16, 2008