# Watch Glass Size question.



## jack_burton (Feb 11, 2012)

What size watch glass is most suitable for 5000ml low form beaker?


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## niteliteone (Feb 11, 2012)

I usually measure the size of the beaker and buy one that is larger than the measured beaker.

Tom C.


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## jack_burton (Feb 12, 2012)

The problem with that for me being I'm ordering online and don't have access to the beaker at the moment.


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## niteliteone (Feb 12, 2012)

Usually when I buy glassware online the seller lists the sizes of the glassware.

What brand and model number are you looking to buy?
I'll try to find out the sizes if I can.

Tom C.

Edit to add:
found this one which would use a 200mm (20cm) watchglass
Size: 28cm x 18cm (10.75 x 7.25")
Capacity: 5000ml or 176oz
http://www.lotioncrafter.com/borosilicate-beaker-5000ml.html


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## jeneje (Feb 12, 2012)

What is a watch glass? and what is it used for? I have heard the term mentioned here before but i have not seen one. 
Ken


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## jack_burton (Feb 12, 2012)

Thank Tom, the 200mm basically answered my question.

Ken- watch glass covers the top of a beaker while you are heating liquid within. Keeps excess vapor from escaping and funnels condensation back into the beaker. Here's a link to a picture of various sized ones:
https://www.avogadro-lab-supply.com/item_images/Watch%20Glass.jpg


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## niteliteone (Feb 12, 2012)

JB,
I looked at several different manufactures and they were all about the same size. The 200mm will work fine and I bought all of mine from avogadro lab supply. Very nice, no imperfections and nice flame polished edges. Good price too.

Glad to help
Tom C.


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## jeneje (Feb 12, 2012)

jack_burton said:


> Thank Tom, the 200mm basically answered my question.
> 
> Ken- watch glass covers the top of a beaker while you are heating liquid within. Keeps excess vapor from escaping and funnels condensation back into the beaker. Here's a link to a picture of various sized ones:
> https://www.avogadro-lab-supply.com/item_images/Watch%20Glass.jpg


Thanks Jack, I will need some of those when i heat AR for my nect project, MCC's 
Ken


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## goldenchild (Feb 12, 2012)

You could use a normal glass saucer if you wanted.


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## Palladium (Feb 12, 2012)

This guy here seems to be having a fire sale on watch glasses. 
http://www.ebay.com/sch/Healthcare-Lab-Life-Science-/11815/i.html?_catref=1&_ssn=mikesnewandused1&_trksid=p3911.c0.m1538


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## Harold_V (Feb 13, 2012)

goldenchild said:


> You could use a normal glass saucer if you wanted.


Two obvious problems. One is a saucer may not be tolerant of being heated. The other problem is density. A heavy glass saucer is likley to break a beaker if there's any bumping. 

Watch glasses aren't cheap, but they're much cheaper than losing values or expensive lab ware. 

Harold


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## The Refiner49er (Feb 17, 2012)

Hi All-

I can't resist posting here, simply as information to save GRF members some of their hard earned money. I have been using tupperware bowl containers with the rounded or tapered bottoms in various sizes for several years that fit well over (or rather into) the beakers as covers, they seem to be effective and I often fill these partially with water or ice to encourage condensation on the inner surface when this effect is desired.

Being made of HDPE, they are acid resistant but do have a lifespan in which they become brittle, but no real loss as they are very cheap if purchased at a thrift store; sometimes the lids work equally as well upside down, so one set= two covers.

Also, thanks for any links for buying watch glass covers, especially the better deals!


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## Palladium (Feb 17, 2012)

I bought 1 dozen 6" watch glasses for $13 including shipping.
http://www.ebay.com/itm/220948962603?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649


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## Barren Realms 007 (Feb 17, 2012)

Palladium said:


> I bought 1 dozen 6" watch glasses for $13 including shipping.
> http://www.ebay.com/itm/220948962603?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649



I bought some of his 3", 4" & 6" they arrived very fast and in good shape, he did a good job of packing them.


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## Palladium (Feb 17, 2012)

Barren Realms 007 said:


> Palladium said:
> 
> 
> > I bought 1 dozen 6" watch glasses for $13 including shipping.
> ...



Got mine today. Fast shipping and they were in the box packed between two pieces of polystyrene and wrapped with bubble wrap.


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