This is a review for the manuscript “Stabilizing Bicontinuous Particle-Stabilized Emulsions formed via Solvent Transfer-Induced Phase Separation”, submitted to Soft Matter for consideration as a full paper. While the subject material is clearly in the remit of the journal Soft Matter, and the work presented is both novel and interesting for the target audience, I think the manuscript should not be published in Soft Matter in its current form.

On the positive side, to the best of my knowledge, the work presented is novel i.e. I am not aware of similar work having been published. In particular, the consideration that surrounding liquids may move into a STrIPS bijel and thereby affect its stability is both novel and interesting. It is also relevant to applications i.e. if STrIPS bijels are to be used for applications, their stability is a crucial consideration. A related observation is, for example in Figure 4, that no comments are made on the qualitatively different shape (concave vs convex) of the plotted curves, which might suggest potentially different mechanism are at play.

However, I have reservations about the analysis of the data presented. First, the concept of “bijel stability” is crucial to this manuscript, see also its title. However, as admitted by the authors themselves, the definition of bijel stability employed here is “arbitrary”. Hence, I feel that the rationale for this definition of bijel stability should be elaborated on, including pros/cons and a justification of the threshold value of 0.5.

Second, I would like to see more consideration of errors in the main text. The visually clearest example is Figure 2(C); only after checking the SI does it become clear to the reader that the data is quite noisy. In addition, there are no error bars on Figure S5, so the significance of the differences here are hard to judge for the reader? Moreover, the curves in Figure 2(C) turn out to be fits to a ninth order polynomial, but what is the justification for that i.e. what is the theoretical expectation for the functional form of \sigma vs r/r_0? Similarly, the threshold for bijel stability is a \Sigma value of 0.5, but only after reading the SI did it become clear to me that the error on \Sigma is of order 0.3, which clearly affects significance and hence has a bearing on conclusions; this should be discussed in the main text.

Third, I have some concerns about the acquisition and analysis of images. Regarding acquisition, more details should be provided about the imaging system, for example magnification and numerical aperture (NA) of the objective used. This is particularly relevant here, as the features of interest here are of order 1 micron, and depending on the objective/NA used, the feature size of interest here may be close to the resolution of the imaging system. Secondly, as far as I can tell, the analysis is done on time series of 2D images, but the re-arrangements in the material are in 3D. This is analogous to trying to make statements about volume fractions of 3D materials by analyzing area fractions in 2D images, which potentially introduces large errors; this should be discussed in the main text. Also, looking at Figure S6, I think there are more straightforward ways to track bijel stability over time from these images.

Finally, the authors provide a credible explanation of the structural changes in the bijel over time, but they should discuss other credible explanations. Notably, the particle contact angle is known to be a crucial parameter in bijel fabrication, but this is not considered in this manuscript (it is for example not listed in Table S14); I think it should be. Just as an example: what if changes to the composition of the liquids in the bijel channels cause a change in the amount of physically absorbed CTAB on the particles, thereby changing the particle contact angle, which in turn could affect bijel stability through curvature effects?

In conclusion, while the work presented in this manuscript is clearly novel and within remit, I have reservations about the analysis of the data presented, and hence I think the manuscript should not be published in Soft Matter in its current form.

Minor points:
- Personally, I feel it should be made clearer in the abstract and at the end of the introduction that this is about StrIPS bijels i.e. the work presented is not necessarily relevant to the stability of bijels fabricated through temperature-induced phase separation.
- Line 107: presumably “of” should be “or”?
- Line 169: the statement about refractive-index matching reducing light scattering and hence enhancing confocal imaging is backed up by a reference involving both authors from 2023, but I am rather sure that this effect had been reported by others before 2023.
- Line 238: “vigorously” should be “vigorous”.
- Line 305: measured viscosity values are mentioned in the main text, so the methods should contain a sub-section on viscosity measurements.
- References: please carefully re-check the formatting, for example references [37, 38, 45] are missing bibliographic information.
- SI line 158: I do not understand what “COLSUA” refers to.
- SI references [4] and [8]: rather than consulting these websites, please could you consult more widely recognized sources, for example the Handbook of Chemistry and Physics.
- Movie S1 from the SI would not open in my Operating System’s default media player.