- No surprises there.

(upbeat music)

Hello, and as always welcome

to the Laramy -K OpticianWorks Training Center.

Couple of weeks ago I got back to back emails

and a special request on,

"Can you help me identify different lens materials?"

And as is so often the case here I say sure!

I can recall being a student

and part of the practical exam for getting your license

in the State of Virginia was lens material identification.

We had stacks of trees, where we would practice this

and think about all the things that we could do

in order to tell what material we were holding in our hands.

The truth of the matter is, it is extremely rare

that you really need to know what material you have.

Let's talk about that a little bit.

Once in a great while, you're gonna have somebody come in

maybe it's an older person they just moved into town

and they had just had cataract surgery

before they left their old place.

The place that they used to go is closed

and you can't get their information from there.

And they had one eye cataract surgery,

done the other one is normal.

And they need that lens replaced.

You take their glasses apart, and you've got this one lens

and you don't know what it is.

I'm gonna give you some tips to figure that out.

What's nice is today so many older folks particularly

have progressive lenses.

If you look at the laser etchings

on the progressive lens, and you have your ID chart,

or you go out online, you can find out exactly

what material that lens is made of, you're done.

A lot of modern single vision does

all your freeform models,

some of your specialties single vision products

they will have it marked on there as well

same thing on the laser etchings.

I think this boils down more often to

what I'm gonna set my edger at

in order to cut a set of lenses if I'm not sure

what material it is.

But again we're gonna find out,

that that really doesn't matter all that much.

What happened during a frame change,

let's say somebody came in,

trying to do a nice thing for them

and take the lenses from the old frame that broke perhaps

and you're gonna try to put them in a new one,

gonna use your edger to do that,

and you need to know what settings you're going to put it on

that's where identifying the lens material you have

is gonna be pretty helpful.

Regardless of what you find

especially in the one lens scenario, do what's right.

If you have somebody in a plus 50, or a minus one

and then in turns out, they are like in a 174,

get them out of the 174 don't just go for that

because that's what they were wearing,

that's kind of over kill.

Another good point to all this,

good part of all of this, is if you're not sure,

you know single vision lenses in particular

are pretty darn cheap.

If in doubt, just do both of them,

it's not gonna hurt anything, if you're priced right

you're gonna come out of the head at the end

when you get this whole thing done,

rather than guessing and putting in the raw material

and having them complain and trying to troubleshoot

and having them come back.

And go out, and come back.

If you're not sure, maybe it's best

just to change both lenses out.

My students had a little saying I really liked,

it said the trivex goes thud,

poly goes plink and plastic goes plunk.

And we'll get over to the bench in a minute

and find out if that's true.

What's nice about this, is you can tell what poly is,

obviously you can tell what glass is,

not that you are gonna edger that anyway.

I'm gonna show you how you can tell what trivex is.

In everything else, is gonna fall

into the high index category.

160 166 167 170 174

and you know what,

the edger just has one setting for high index

so it's really not gonna matter.

We're gonna run through every single possible material

I could get my hands on.

I got them in plus, I got them in minus.

Got them in two different manufacturers,

where ever I could do that,

and we're gonna run through them all.

We are gonna talk about what that material feels like,

what that material looks like,

what that material sounds like

and yes even what that material smells like.

Welcome to the bench, let's get going.

Little awkward today,

I needed a counter that sounded like a counter

you would have at work,

so I had to kind of rearrange the studio a little bit.

Just as always I try to do my very, very best

to get you a mixed of really common lenses.

Common manufacturers, common powers.

Stuff that you would have sitting around the office

and maybe you mixed up the lens packages.

Knowing and being able to identify lens materials

is a handy thing to know.

It's not quite as important as it used to be.

One of the other reasons for that is of course AR coatings

unless they are within a month or so of each other

you're really forced to replace both lenses not just one,

so it doesn't really matter which material

you're talking about.

Our business point, you know the absolute bare minimum

that you're ever gonna do on a lens markup is two times.

If you had to for some reason, do a pair

in lieu of one at least you're gonna break even.

We all know what glass sounds like,

I don't think we're gonna need to go into this

a whole heck of a lot.

I am dropping these things from a height

of about 10 and a half inches.

Glass obviously, (clinking sound)

No surprises there.

Next I have got to 174 series from Seiko

the only company that those are available from.

This is a minus two,

it has a little bit of flexibility not a lot.

It has an AR coating, it comes with it

you can't order it without.

It also got a satin polish finish to the outside edge

and it sounds like this in the minus (mumbles)

(plunking sound)

I should talk over that, should I?

(plunking sound)

This is a plus two uncut.

(plunking sound)

And this is a minus two cut.

(plunking sound)

And that's 174.

Oh you know what else,

uh-huh can't forget this, very important.

Think I've got a high index, let's see if it smells.

(machine grinding)

It sure does, it has a very mild garlic

high index smell to it, so there's another tip.

Tribrids kind of a rare thing

we don't see them very often here,

They were actually kind of hard to get

but I did track down a couple

and this is a minus two,

it has some flexibility not a heck of a lot really.

Almost like a satin polished edge to it.

Minus two uncut, sounds like this.

(plunk sound)

And a minus two cut sounds like this.

(plunk sound)

Does Tribrid smell?

Let's find out.

(machine grinding)

No, not really.

Next we move on to a high index 167

this does come in a couple different manufacturers

and why would that matter?

It's because of the coating on the outside

it's gonna change maybe perhaps the way it sounds.

A 167, little flexibility

much like all the others, almost a clear edge.

This one does not have an AR coating,

this is a minus 150 uncut.

(plunk sound)

And let's see if it smells.

(machine grinding)

Not very much, I was actually expecting a little bit more,

will try the other brand as well.

Here is a 167 plus 150 uncut.

Here is a plus 150 uncut in a different manufacturer.

(plunk sound)

Here is a minus 150 uncut.

(plunk sound)

167, boy that has a pretty distinctive

(plunk sound) distinctive sound.

And here is a 167 cut.

(plunk sound)

And I said we were gonna see

if this smells anymore let's find out.

(machine grinding)

No, not that much.

I was really expecting a little bit stronger odor from that

the 174 were very distinct, the 167 not quite so much.

Moving on to our very traditional trivex lens.

I think the biggest giveaway on the trivex

is the flexibility in it,

I mean you can almost fold this thing

over if you wanted to, now that's a huge tipoff.

Translucent satin finish kind of edge to it.

A minus 150 uncut.

(thud sound)

A plus 150 uncut.

(thud sound) That's it, kind of that thud sound

the debtor empty sound.

A plus 150 (thud sound)

(chuckles) That's pretty distinctive.

And a minus 150 (thud sound)

And a cut minus 150 in trivex.

(thud sound)

Honestly, I think their description of the thud of a trivex

is actually a pretty good one.

Polycarbonate, polycarbonate a minus 150.

And I think the sound is what really gives poly away.

The edge on a poly in a molded blank like this

is crystal clear another, it's another tipoff for you.

Quite rigid, I mean it has some flexibility

but it sounds like it's rigid, and feels pretty rigid.

And of course a super distinctive sound.

A minus 150, (plink sound)

A plus 150 (plink sound)

You see that most people describe it

as the sound of a poker chip

particularly when we get to that cut one.

Plus 150 (poker chip sound)

A minus 150 (poker chip sound)

High pitch sound.

In a cut minus 150 we we'll really hear that

very distinct poker chip sound.

(poker chip sound)

That one is pretty easy to identify.

And we're gonna wrap up our lens material ID session

with plastic, this is a CR39, kind of heavy,

it's kind of thick has a translucent

almost an unpolished edge,

it's a very matte finish.

It's got a little bit of flexibility

it's very, very rigid.

That hollow sound.

A minus 150 (plink sound)

A plus 150 (plink sound)

A plus 150 in a different manufacturer (plink sound)

A minus 150 (plink sound)

And a cup plastic or CR39 lens (plink sound)

guess one other last tipoff I would say

is that mostly a high index lenses,

your glass and your plastic,

are probably the only ones that don't have

a slightly gray shin to them

when you're looking at a white background.

I had one other question pop up

when I started looking into identifying lens material

and that was can you identify a lens material

by its center thickness?

Hey, it was a great question.