100mm Plain Watch Glass Beaker Cover, Karter Scientific 213H11 (Pack of 10)

I use these for craft purposes and they are not suitable for craft use AT ALL! There are deep scratches in the glass, some have bubbles or imperfections around the rim, and the worst part is the thick film on the glass that DOES NOT come off with vigorous scrubbing!!!!! For scientific use Im sure they are fine but for craft use DONT BOTHER!!!!!!!! It is aggravating when you are on a time line for an order and over 1/2 your order is unusable. Sorry to be harsh but Im being truthful and I dont want anyone else to go thru the frustration!

Tiny flies can find a glass of (whatever I'm drinking) quicker and in higher concentrations than you can believe. Keep them from drinking your beer by placing one of these over the top between quaffs. Or use them as weighing dishes, or evaporating dishes, or for covering beakers, (or even protecting watch dials I suppose), whatever.Mine are only 98 mm, but the edges are smooth and I've only broken one (hit the bench just wrong, oopsy--and no, it was the next day....)

I received mine in a crushed box "not the sellers fault" UPS guy doesn't like me.All of the glasses still had grinding powder on the and a couple ad chipped edges.After cleaning with a mild acid and soap, I found most had abrasive surface scratches on them.They are not Borosilicate glass as some reviewers have said they are plain Flint glass as stated in the description. I have discarded two glasses but the rest are OK for what I am using them for. I will be sure not to use them when heating liquids in a flask. They should be labeled as defective or second use.

These came well packaged in a small cardboard box. There was thin paper between each watch glass and enough extra to protect the whole stack of 10. None of mine contained any bubbles or scratches and the ground edges were plenty smooth. Used as a beaker cover they perform exactly as I would expect and keep bubbling liquid from splashing out.

I ordered these because at less than a dollar a watch glass, it was worth checking out. That said, these are good! They serve their purpose just as well as hardware costing many times more. Mine arrived unbroken and perfectly useable. There are no glass imperfections that I noticed, and can be abused just like their more expensive cousins. They may be a little thinner than what you're used to, but handle them gently and it's all ok. I recommend these for sure. At 76 cents a piece, you can't really go wrong.

I need to preface this review to state that I did not purchase these for lab or science reasons, but for crafting purposes.I don't know enough about borosilicate watch glass or Karter Scientific to know where the problem lays. I ordered two boxes of 10pcs. They arrived packed in the product's box, inside a padded envelope, surrounded by crumpled paper inside a box, inside another box. Seemed extreme but....One glass is cracked and is unusable. A few are scratched. Most the glasses have multiple chips around the edges, though most are very small. Mos, if not al, of the glasses some kind of bubbling or flaw appearing on the convex side of the glass. I tried to scrub it off in the case that it was just dirt or some kind manufacturing residue, but I don't seem to be able to remove it.I've purchased these for crafting purposes and I think their condition is bad enough I won't have a good end piece, but I have decided to keep them to use for learning. I may try to find a lab technician and see if this is normal for the product.

I was looking to use these for chemistry stuff. They aren't necessarily made of the clearest glass but tbh if you're buying them for their recommended use, they're perfect! I haven't tried heating them yet, because I don't really think they'd hold up to direct flame, but so far they work well as beaker covers and specimen holders.

These are simple glass. The edges are ground, not smooth fire-polished as stated in the description. The glass itself is average, not high-end, meaning it may contain bubbles or rough spots.These were more than adequate for my purpose of covering wine glasses after pouring several sample per person for a cognac tasting. YMMV.