Coverslipping Part 2: Liquid Glass

By: Nuria Bosch, Lucas Pena, Jaime Augusti, Federica Melone, Carmelo Lupo, Samuel Caboni, Paolo Locatelli; Pathology Department, Diapath

In Part 1 of this series, the S/C poster presenters from Diapath, shared their research into the problems associated with traditional methods of coverslipping. To address these problems, they compared traditional methods with the newer coverslipping option, "liquid glass".

Liquid Coverslipping Technology: Liquid Glass

Cristallo is a new “liquid glass” for coverslipper technology, that creates a homogeneous layer above the sample. The created micrometric film allows an optimal microscope view experience, due to the refractive index of 1.5, very close to that of the glass and that of the fixed protein (tissue) (approximately 1.53) [3]. Cristallo liquid can be used in both manual mode and automatic mode, by using standard coplin jars and any automatic stainer in the market. After hardening time, slides can be analyzed under the microscope and stored as standard glass covered slides, ensuring also a better plasticity than silica glass coverslips. The extreme sensitivity of the glass surface to damage leads to considerably lower strength values reported in the literature for bulk samples (of the order of 20 MPa) [7] in other words: what doesn’t bend, breaks.

Materials and Method: Comparison of 104 Histology and Cytology Samples.

89 samples of various tissues have been cut with standard methods (rotary manual microtome). 2 sections of each sample block have been placed on two different slide glasses for staining. 15 Liquid cytology samples have also been processed. The first group of slides have been stained with automatic stainer (HE and Papanicolau staining) and afterwards mounted by using an automatic cover slipper. The second group of slides (mirror slides) have been stained with the same protocol as the first group and then dipped into Cristallo (Liquid Coverslipper) for 2 minutes at room temperature. After 15 minutes at room temperature the slides have been analyzed under the microscope. Pathologists involved in the evaluation, compared the two groups of slides without knowing in advance which group each slide belonged to.

Evaluation Criteria

For both series (standard coverslipping and Cristallo), 2 technical criteria and 1 economical criteria have been evaluated:

Presence of Bubbles: Presence and quantity of eventual bubbles that makes the investigation difficult to perform (rating from 1-no bubbles to several bubbles)

Quality of the Staining: The evaluation of the quality of staining (colors, contrast, sharpness), (rating from 1-poor to 5-very good)

Price Per Slide: Traditionally, financial analysis has been done as a bottom-up analysis using directly identifiable costs [8] often considering coverslipping as a part of staining costs. In the present study, coverslipping has been spun off and calculated considering purchasing price of the automatic coverslipper, amortized price for 10 years, (A) , maintenance cost (service) (B) and consumable costs (mounting medium and coverglass) (C). This was compared to the cost of the Cristallo scenario.

The results are preliminary shown in the chart below:


Results show that the Cristallo method, ensured quality of evaluation, thanks to stunning clarity, deep contrast, and brilliant color combination, offering similar performances under a microscope as standard method (glass coverslipping), allowing a significant time saving that ensures a reducing of TAT (turnaround time) of Histology reports. As recent studies demonstrated, the need for more rapid communication of biopsy results is becoming crucial [9]. Also a result of the liquid coverslipping method was the not negligible improvement of quality of the staining; this advantage could be useful for histology and cytology cases.

By using the liquid coverslipping, histology labs are able to save starting cost (investment in purchasing an automatic coverslipper) and/or maintenance costs of the same. Considering this, we can say that the cost of the reagent is widely compensated, guaranteeing savings in the laboratory.

To complete the overview of this validation, it is important to underline the benefit in terms of toxicity of the reagents in the pathology lab. Cristallo shows neither GHS08 nor GHS07 pictograms. For this reason, it is not associated with any human health risk, acute nor chronic.


1. Mark R, Wick MD, Diagnostic Histochemistry , 11–12 (2008).

2. Carson L, Cappellano CH, Histotechnology, a Self Instructional Text , 71(2015).

3. Ravikumar S, Surekha R, Thavarajah R. “Mounting media: An overview”. J NTR Univ Health Sci 2014;3, Suppl S1:1-8

4. Brown PA. “ A review of technique used in the preparation, curation, and conservation of microscope slides at the natural history museum London ”. The Biology Curator 1997; 10:1-33

5. Morelli P,et al.Analysis of errors in histology by root cause analysis: a pilot study” J Prev Med Hyg. 2013; 54(2):

6. Ellys P, “ Problems in Histopathological Technique . IHCWORLD 2002. Problem 30.Web.

7. Guin JP et al., “Plasticity at nanoindentation site in glass :a possible experimental benchmark for numerical modeling” 22ème Congrès Français de Mécanique (2015)

8. David M et al., “ Pathology Economic Model Tool “A Novel Approach to Workflow and Budget Cost Analysis in an Anatomic Pathology Laboratory” Arch Pathol Lab Med—Vol 134, 2010

9. Lang EV et al., “Large-Core Breast Biopsy: Abnormal Salivary cortisol profiles associated with uncertainly of diagnosis” Radiology 2009, 250(3)

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