Friday, March 06, 2026 Our provisional answers to A 2026

Like last year, Nyske and Nico were benchmarkers for paper A. We both concluded that this was not an easy paper. Though we both identified the same relevant issues and problems to be solved in the paper, we sometimes made different decisions or took a different approach. We hope that the Exam Committee will take different solutions into account for this paper, as we feel that in view of the information in the paper that would be justified.

This was a classic “chemistry-style” paper, with various different claim categories that all seemed to have their own specific issues involved. While generally it was clear what was novel in view of the prior art, what can be considered to be inventive was less clear.

Sometimes a careful sorting of terminology was required, in particular regarding the distinction between the composition and the coating, which resulted from the composition being applied to a substrate and then dried/densified to obtain the coating with the original starting materials disappearing, and the relationship between the substrate, the cooking surface, and the different layers. Usually you can rely on the text of the client’s letter to provide you the proper claim terminology, we feel that was less so in this paper. The text in the client’s letter needed careful revision to arrive at a clear and consistent claims set. For example, their seems to be a subtle difference between the sol-gel coating (final product) and the sol-gel composition (mix of precursor and gel starter), but the respective wording does not seem to be used consistently in the paper. For example, in par. [006] it is said that all sol-gel compositions are inorganic – which is true for the finished coating but not for the mix of precursor and gel starter. In addition, in view of the complexity of the paper and the amount of different issues to contend with, we would not be surprised if many candidates missed these more subtle issues and we hope that the marking scheme will have some leniency in this respect.

The invention appears to rely on certain combinations of sol precursors and gel starters. These components are individually disclosed in D2, but specific combinations are new according to the two-lists selection principle. The question is however which combinations would be inventive. Par. [010] mentions that all coatings the client prepared have good non-stick properties, are scratch resistant and safe to use with food. One of us interpreted “all coatings we have prepared” as being the coatings in the table, and the listed advantages of “all coatings” to be a basis for inventive step. However, the advantages mentioned in par. [010] seem to match the general advantages mentioned in par. [001] and [006] of D2. For the specific combination of TEOS and citric acid it is mentioned that this achieves “by far our best results”, so this seems to be the safest option to claim as it seems to provide the largest benefit (see Table 1, hardness 12-15). But what exactly the benefit is over the prior art remains unclear since D2 neither mentions specific combinations nor hardness values.

The precursor and gel starter are organic components which, according to paragraph [007], are no longer present in the final coating. This creates a practical difficulty when claiming the end products, such as the coated cookware item or possibly the sol-gel coating itself. One could consider claiming the end products using a parameter (specifically the hardness, which seems objectively and reliably measurable since an ISO standard is mentioned) but in our (admittedly E/M-biased) view this is too much of claiming a result to be achieved. This leaves product-by-process claims as a realistic option.

The automatic spraying system appears to differ from D2 in three respects:

1. a moving speed between 0.1 and 0.8 m/s (as D2 says that the speed may be lowered to 1.5 m/s in case of complex areas the skilled person would not seriously contemplate the lower part of the range as disclosed in D2);
2. the way in which the sprayer is moved and positioned to spray horizontal surfaces and vertical or inclined surfaces;
3. the use of different sol-gel compositions (e.g. ratios of 4:1 and 2:1) for horizontal surfaces and for vertical or inclined surfaces.

Features (1) and (2) appear very non-unitary with the rest of the claims. For this reason, the claims below mainly focus on feature (3), which has at least some form of overlap with the rest of the claims. Also, the ratios 4:1 and 2:1 are quite specific as they are single numerical values, and therefore offer quite limited protection. The technical effect seems to be achievable already if a lower TEOS-to-citric-acid ratio is used for the vertical or inclined surfaces than for the horizontal surfaces. However, this wording is not present in the paper, so it is unclear whether this formulation would have been expected (although it would arguably still be new and inventive over D1 and D2).

It should also be noted that an automatic spraying system using the novel or inventive sol-gel composition would not necessarily be novel over D2, because the composition is not a structural feature of the spraying system itself. However, this could be addressed by a use claim, for example “use of the automatic spraying system to apply a sol-gel composition according to any of claims X–Y”. The claim set below does not include such a claim, since claim 8 already follows a somewhat similar approach. However, this would still be a viable option.

Note that one of us took a different approach and went for the speed range in the independent claim for the spraying machine and adding that the machine is suitable for applying a sol-gel composition to a cooking surface of cookware. Inventive step was defended based on par. [014] saying that the moving speed can be adapted to apply the coating efficiently and thereby optimise production costs. Such a claim seems to provide the broadest protection for the spraying machine but unity of invention seems shaky.

Below you’ll find a claims set that we think is defendable. However, as already noted, this is not the only claims set that we consider to be a reasonable solution to the paper.  

What is not included in the claim set below?

• A product-by-process claim directed to the sol-gel coating itself. This could have been possible, with the cookware item then being claimed as a dependent claim on the coating.
• A method of making the sol-gel composition itself, for example by combining the sol and gel components in the desired ratio and without including the subsequent drying step. However, the product claim directed to the composition itself appears to provide better protection, and the maximum of 15 claims is already easily reached.
• Finally, what about the reference to ISO 14705 of 31.12.2016? This might suggest that a parameter claim could be possible. As explained above, we didn't interpret this as a claimable parameter, but instead used the ISO standard in the introduction to demonstrate that the claimed sol-gel composition and resulting coating provide a technical effect / improvement over the prior art.

Claims

1. A sol-gel composition comprising TEOS (tetraethylorthosilicate) and citric acid in a ratio by weight of between 1:1 and 6:1 of TEOS to citric acid.

2. The sol-gel composition of claim 1, wherein the ratio by weight is 4:1 of TEOS to citric acid.

3. A method of coating a substrate using the sol-gel composition of claim 1 or 2, comprising:

- providing the TEOS and the citric acid in the ratio by weight of between 1:1 and 6:1 of TEOS to citric acid;

- performing a gelation by adding the citric acid to the TEOS to obtain the sol-gel composition;

- applying the sol-gel composition to a substrate to be coated;

- performing a drying-densification of the substrate at more than 250°C.

4. The method of claim 3, wherein the substrate is a metal substrate of a cookware item.

5. The method of claim 4, wherein the metal substrate is an aluminium layer of the cookware item.

6. The method of claim 3 or 4, wherein the cookware item comprises one or more horizontal cooking surfaces that are horizontal during cooking and one or more non-horizontal cooking surfaces, the method further comprising:

- providing a first and a second sol-gel composition of TEOS and citric acid, wherein the first sol-gel composition comprises a first ratio of TEOS to citric acid and the second sol-gel composition comprises a second ratio of TEOS to citric acid, wherein the first ratio is higher than the second ratio; and

- applying the first sol-gel composition to the one or more horizontal cooking surfaces and the second sol-gel composition to the one or more non-horizontal surfaces.

7. The method of claim 6, wherein the first ratio is 4:1 of TEOS to citric acid, and/or wherein the second ratio is 2:1 of TEOS to citric acid.

8. The method of any one of claims 3 to 7, wherein applying the sol-gel composition to the substrate comprises using an automatic spraying machine.

9. A cookware item (10) comprising a metal substrate (21), wherein the metal substrate comprises a cooking surface, wherein the cooking surface is coated with a sol-gel coating obtainable by the method of any one of claims 3 to 8.

10. The cookware item (10) according to claim 9, wherein the metal substrate comprises an aluminium layer (21) which comprises the cooking surface.

11. The cookware item (10) according to claim 10, wherein the metal substrate further comprises another metal layer (22) underneat the aluminium layer (21).

12. The cookware item (10) according to claim 11, wherein the other metal layer (22) is a stainless steel or iron layer.

13. An automatic spraying machine for applying the sol-gel composition of claim 1 or 2 to a cooking surface of a cookware item, comprising:

- sprayer (30); and

- a control system to control the sprayer to move within geometrical boundaries of the cooking surface and to apply a sol-gel composition to the cooking surface;

wherein the cookware item comprises one or more horizontal cooking surfaces that are horizontal during cooking and one or more non-horizontal cooking surfaces, wherein the control system is configured to apply a first sol-gel composition with a first ratio of TEOS to citric acid to the one or more horizontal cooking surfaces and a second sol-gel composition with a second ratio of TEOS to citric acid to the one or more non-horizontal cooking surfaces, wherein the first ratio is higher than the second ratio.

14. The automatic spraying machine according to claim 13, wherein the control system is configured to apply the first sol-gel composition to the one or more horizontal surfaces by spraying the first sol-gel composition orthogonally to a horizontal plane of the one or more horizontal cooking surfaces, and subsequently applying the second sol-gel composition to the one or more non-horizontal surfaces by maintaining the sprayer in a position which allows the sprayer to spray the second sol-gel composition horizontally and moving the sprayer to apply the second sol-gel composition to the one or more non-horizontal cooking surfaces.

15. The automatic spraying machine according to claim 13 or 14, wherein the control system is configured to move the sprayer at a speed between 0.1 and 0.8 m/s.

- Nyske and Nico