1000ml Volumetric Flask, 3.3 Boro Glass, Class A, Ground Stopper, Karter Scientific 213W8 (Pack of 2)

I started out using these by validating their markings using distilled water and something isn't right. For both of these, they appear to have been marked using a height gauge or something similar and I think that's ok. What I'm having trouble with is the fact that both of them appear to be out of spec by about 1.5mL - I have to add 1.5mL to get a full 500 grams, so the flask is technically over-full. I marked the 500mL level on the neck and then proceeded to further validate it using a non-electronic triple-beam balance and I got the same result. So, two different balances agree that the marking is wrong and I've done the validation in two different directions. In one case, I started with the Ohaus SPX2202 and filled the flask to 500 grams. This agreed with the mark I put on the neck earlier. I then emptied the flask into a beaker on my Ohaus 700 series triple beam balance, stopping at 250 grams twice over to get to 500 grams. Both balances agree with each other - both flasks appear to be incorrectly marked.I can still use them, I just can't trust the markings on them until I figure out why this is happening. Maybe gravity is less here than it is elsewhere? Will keep an eye on it and post an update if an explanation appears.Update: I calibrated my SPX2202 using the Ohaus calibration masses and I still get the same result. Worse, I've also checked this with another electronic balance, and the factory marking is still incorrect. If you are keeping score, 3 different balances (one of them calibrated to a standard) and all of them indicate that these are not within specification. I can't explain it. I've never had this issue with Karter Scientific products previously.

Wonderful product! Will buy more later for sure

So I'm not an expert on laboratory glassware but I don't find these to be of the highest quality. There are lots of imperfections in the glass, scoring in multiple places, and chips around the rim of the ground stopper. The two in the package are different sizes and the volume mark is in a different place. I'm guessing this is just fine. Probably hand made, filled with a known quantity, and then marked for volume. For my purposes I think they will be fine and I'll use them until they break.The packaging they came in was very good. Bubble wrap in the box, each flask came in its own padded envelope, the stoppers were wrapped in paper, and additional cardboard lattice padding on top and bottom.I'll update my review when I test the volume measurement.

Used balance, a glass pipette plus an adjustable pipette at 10ml.QS mark matched both pipettes very close. Karter products have performed as advertised so far.

Is exactly what it is

i like the product, well packed, the price is right,

came well packed. is exactly as presented. high quality

I have been teaching chemistry for 27 years. These volumetric flasks fit the bill for teaching students how to make diluted solutions! The flasks were perfect quality, arrived well-packaged and are perfect for my classroom needs.

Un matraz me llegó con el tapón de vidrio estrellado, además el vidrio de los matraces presenta rayones que le restan estética. Todavía no los sometos a ciclos de calentamiento y enfriamiento, espero resistan bien.

these volumetric glasses are accurate

Product is as described

Poor quality. This company does not provide quality lab equipment. It is for the dabbler or drug synthesizer

As it should be!