Appendix: Full technical report

1. This evaluation was to test the suitability of a range of LabGlass® laboratory glassware for use in UK school laboratories.

2. The glassware supplied comprised one of each of the following: 

• 100 ml & 250 ml beakers (CH0124C and CH0124E)
• 100 ml graduated flask (CH0442CWT)
• 200 ml conical flask (CH0424E01)
• 100 ml measuring cylinder with protective guard (CH0341D)
• 25 ml burette (CH0236B)
• 125 ml reagent bottle (CH0160C)
• Simple organic chemistry set (CH0881)
• Two different sizes, light wall, rimmed test tubes (CH0718 range)​

3. The organic chemistry set came packed in foam inserts in a cardboard box. It had 14/23 ground glass joints which means the nominal diameter of the larger end of the joint is 14 mm and the nominal length of the joint is 23 mm. The kit comprised:

• 14/23 Liebig condenser
• 14/23 25 ml pear-shape flask
• 14/23 Fractionating column
• 14/23 Still head
• 14/23 Receiver adaptor
• Thermometer holder
• 100^OC 76 mm immersion, spirit thermometer
• 20 ml beaker.

4. Most of the glassware was marked with the Eisco LabGlass® trademark.

• The ground glass items in the organic chemistry set were also marked BORO3.3 and, where relevant, 14/23.
• The burette was additionally marked 0.1 ml ± 0.05 ml, A, ISO 385, EX 20^OC, BU25 12034. In addition, the box in which it was supplied was marked GLASS BORO 3.3, chemical resistant, autoclavable.
• The volumetric flask was marked 100 ml ± 0.16, TC 20^OC, B, acc ASTM E288, T/S13, BORO3.3. Its box was marked like the burette box.
• The measuring cylinder was marked 100:1.0 ml, A ± 0.5 ml, ASTM E1272, TC 20^OC CY100 12034.
• The conical flask was marked 200 ml, BORO 3.3, CH0424E01. It also had approximate volume markings.
• The beakers were marked 250 / 100 ml, BORO 3.3, CH0124E / CH0124C. They also had approximate volume markings.
• The reagent bottle was marked 125 ml, BORO 3.3.
• The borosilicate test tubes had no markings.

5. ISO refers to standards produced by the International Organization for Standardization. ASTM was originally the American Society for Testing and Materials but is now an international standards organisation. Teachers or technicians (and examiners) in the UK will generally not be familiar with ASTM standards but will expect relevant items to comply with British Standards (BS) or European / ISO Standards adopted as British Standards (BS EN or BS ISO).
BS, BS EN and BS ISO standards and some IEC (International Electrotechnical Commission) standards were verified but it was not possible to verify the ASTM standards, and so it was not possible to confirm their relevance.
The company reports that typically they only supply ASTM glassware to the USA market – the ASTM sample supplied was requested by ASE for the assessment. However, they prefer ASTM standards on some glassware such as beakers as these require full scales to capacity duplicated on both sides which is more user-friendly than the scales required by ISO standards.

6. The marking BORO3.3 on most of the glassware implies that it complies with BS ISO 3585 Borosilicate glass 3.3 Properties, which means it is deemed satisfactory for the construction of laboratory glassware. However, as CLEAPSS points out (Laboratory Handbook 9.11.1), the standard does not concern itself with aspects of quality control during manufacturing processes. Poor quality control can result in the glass not being of a uniform thickness, or if the annealing time was too short there could be greater stresses and strains in the glass, any of which could result in greater fragility, especially if heated. Thus BORO3.3 is a necessary but not sufficient condition of suitability.

Correspondence with the company stated that the volumetric apparatus is calibrated in their ISO17025-compliant laboratory. (More correctly, from our point of view, BS EN ISO/IEC 17025 compliant.) This standard is, in effect, a management standard and not a technical standard but does imply methods of ensuring compliance with the relevant technical standards.

7. The reagent bottle had a plastic stopper, the graduated flask had a ground glass stopper (not of a size compatible with the jointed glassware) and the burette had a ground glass tap (held in place with a plastic cap). However, many items are offered with the option of glass or plastic stoppers, and burettes are available with PTFE taps.

8. For items of normal UK school equipment, variations in price between suppliers are sometimes usually because of variations in quality control. Cheaper items may result from a smaller fraction of the production being checked for quality compliance. Checking a few items in this sort of evaluation is quite unable to test that. However, LabGlass has been well established in UK schools for over five years and the company reports that has not been made aware of any quality or safety concerns during that period.

Tests carried out

9. The following tests were carried out, mostly courtesy of the CLEAPSS laboratories.

1. A visual comparison of the LabGlass® glassware was made with comparable glassware from the shelves at CLEAPSS. This included glassware from Pyrex and, in some cases, other manufacturers. The selection is believed to be typical of what would be found in schools.
2. The thickness of the glass and consistency of the thickness at four roughly equidistant locations around the circumference of the two beakers was measured with a micrometre screw gauge and compared with Pyrex and other beakers of the same size. Note: because of the way the gauge contacts the curved surface of the glass this will not give the actual thickness, but will give a measure of the consistency of the thickness and its relative thickness compared with other brands.
3. Solid samples of hydrated copper(II) sulfate were heated until anhydrous in the smaller test tube. When cool, the samples were then rehydrated.
4. Sodium hydroxide pellets were weighed, dissolved in de-ionised water in the beaker and then transferred to the volumetric flask. 10 ml aliquots of vinegar were titrated with sodium hydroxide solution, with the alkali in the burette. It is normally recommended that the alkali should not go into the burette, because of its corrosive effect on glassware, the formation of sodium carbonate from atmospheric carbon dioxide causing problems with the tap and the alkali attacking the grease sometimes used to lubricate the tap. Nevertheless, it is sometimes necessary for schools to go against good practice and was felt to be a reasonable test of the equipment.
5. The jointed glassware in the organic chemistry kit was tested for general compatibility with non-Eisco glassware. A coloured liquid was then distilled using the kit.

Visual examination results

10. For the most part, the visual comparison showed little difference between the LabGlass® glassware and the other available glassware, some appeared thicker, some thinner. The test tubes were both 150 mm long and had internal diameters of about 15 and 24 mm. 150 mm is quite long for the narrower size (commonly 100 or 125 mm long) but should not affect performance. For a few items examined, there were significant differences, however.

11. CLEAPSS had no 200 ml conical flasks, so the comparison was made with Pyrex and Simax 250 ml conical flasks. The LabGlass® flask appeared to be of thicker glass, but more importantly, the neck of the LabGlass® flask appeared significantly narrower. This was confirmed by measurement with a ruler. The internal diameter of the Pyrex flask was 24 mm, the Simax 32 mm and the LabGlass® 27 mm. A wide-necked version is also available and would be more suitable if used for titration: learners using the narrower neck version might find it harder to manipulate the flask under the tip of the burette and to avoid getting drops from the burette on the neck of the flask, where it would not mix properly.

12. The original LabGlass® still head from the kit of jointed apparatus was significantly different in appearance from the three different ones in the CLEAPSS laboratories, in that it appeared much larger. This was confirmed by measuring with a ruler. The vertical distance from the tip of the cone to the top of the socket was 133 mm for the LabGlass® one, compared with 96 mm for the Quickfit one, 86 mm for the Exelo one and 108 mm for the Christinson one. The side arm was also longer. From the top of the bend to the top end of the cone, the distances were: LabGlass® 62 mm, Quickfit 38 mm, Exelo 43 mm and Christinson 43 mm. In addition, the side-arm appeared much nearer the horizontal than the more steeply sloping arms of the other three. With the equipment available, it was not easy to measure the angle reliably. However, if it was not sloping steeply enough, condensate in the attached condenser might not run down to the end. The much larger size of the still head compared with the others would result in more ‘dead space’. The pear-shaped flask was 25 ml capacity, and the smallest on the CLEAPSS shelves was 50 ml. The small size would necessitate using smaller quantities of chemicals, which in itself is a good thing – cheaper, greener, and less waste.  The company has been most responsive to this finding and has redesigned the still head for future distillation kits. The replacement LabGlass® still head is visibly improved with smaller dimensions and a visibly steeper-angled side arm.

Test results

13. The tests resulted in the following findings.

13.1. As might be easily predicted, when the 100 ml beaker was dropped on the floor from a height of 90 cm (bench height) it broke (but did not do so from 75 cm.)

13.2. The thickness of the glassware, measured at four approximately equally-spaced points around the circumference of the 250 ml beakers, about 1 cm below the rim, was as follows. Based on these measurements, the LabGlass® glassware appears to be of as consistent thickness or better than that commonly found in schools and so in principle should be at least as robust, assuming, of course, that this was a typical sample.

13.3. A few grams of copper(II) sulfate-5-water was heated until anhydrous in the smaller LabGlass® test tube (150x15 mm) and a similar but shorter Pyrex one. The samples were then re-hydrated. Unsurprisingly, more condensation formed on the cooler parts of the longer tube, but otherwise there was no significant difference in the performance of the two tubes.

13.4. The volumetric glassware performed as expected. The markings on the volumetric flask and on the burette were easy to read. The glass tap on the burette turned smoothly, allowing easy dropwise addition close to the end point, resulting in consistent titres. However, this was a new flask and burette so nothing can be said about the long-term legibility of the markings or the continuing smooth action of the tap. After some use, glass taps can become stiffer, requiring lubrication, which, if badly applied, can result in the bore hole becoming blocked. Eisco also supplies 50 ml burettes with PTFE taps at a not much greater price than the glass tap variety, which may be preferable for schools.

13.5. When the glass-jointed kit was used to distil a coloured liquid, much condensation was observed in the still head before reaching the condenser and it was slow to run down as if it was not wetting the glass very well. It was difficult to see exactly what was happening, so some of the coloured liquid was allowed to splash over and it immediately became apparent that there significant pooling in the side arm of the still head, just before the ground glass joint. The experiment was then repeated, replacing the LabGlass® still head with a Quickfit one, but all the other apparatus was from the Eisco kit. As expected, there was much less condensation observed in the still head, more in the condenser, and virtually no pooling in the still head itself ASE expects the redesigned LabGlass® still head will now perform perfectly well.

Conclusions

14. Although a list of prices was supplied with the apparatus, a comparison of the price of LabGlass® items listed in the catalogues of UK suppliers with those of other manufacturers in the same catalogues. In almost every case the LabGlass® item was the cheapest. It was commonly one-quarter or one-third the price of traditional Pyrex-type glassware and significantly cheaper than suppliers such as Simax.

15. Eisco supplies 50 ml burettes with PTFE taps at a not much greater price than the glass tap variety evaluated, so schools would probably prefer it.

16. UK schools will expect volumetric glassware, at least the glassware used for public examinations (burette, bulb pipette and volumetric flask) to comply with BS EN ISO 385 class. The burette was class A and so exceeded requirements but could be used. The volumetric flask complies with an ASTM standard rather than an ISO standard – this flask was requested by ASE in error. However, volumetric flasks that comply with ISO standards are also supplied by LabGlass®.

17. The volumetric glassware performed perfectly satisfactorily but one problem can be that the graduations/markings become difficult to read over a period of time. No conclusions can therefore be reached about how satisfactory it would be over the longer term.

18. UK schools will expect the cones and sockets of the jointed glassware in the organic chemistry kit to be compatible with any ground glass apparatus they already possess, eg Quickfit. No problems with compatibility were found. However, the relatively large size of the still head meant that it did not perform well enough and cannot be recommended.

19. The borosilicate test tubes had no markings at all but were relatively thick-walled (for light-walled tubes) and withstood moderate heat in the tests.

20. UK schools will expect the general glassware (test tubes, beakers, etc) will be robust enough for the usual careless/untrained handling to be expected of teenagers. Breakages are to be expected through dropping or knocking or inappropriate heating. The tests carried out were intended to mimic what might reasonably happen in schools. ASE did not have access to the highly specialist facilities of a test house examining compliance with volumetric glassware standards, for example, and no attempt was made to reproduce them. Schools will expect the glassware to be comparable to other glassware on the market, e.g. Pyrex, Duran, and Simax. Increasingly, UK schools have been purchasing cheaper but less thermally resistant neutral borosilicate glass. All the Eisco glassware supplied, except the test tubes, are marked BORO3.3 and so are borosilicate. The company reports that test tubes are also made from Borosilicate 3.3 glass. However, quality control for all the items may be worse or better than that for those commonly bought. Only testing a large, random sample would be able to resolve that issue, which is beyond the scope of this evaluation, although any obvious deficiencies have been pointed out.

21. All the equipment tested apart from the still head was satisfactory and performed well in the laboratory. Whether it is less robust or more robust in a UK school context can only be ascertained by putting the equipment in schools for a period of time.

22. Given that the Eisco LabGlass® equipment tends to be cheaper, in some cases a great deal cheaper, than apparently similar equipment on the market, there is no reason why schools should not try it.