*2.2.3 The assessment of the support material (canvas) of the paintings*

The study assesses the quality of the initial materials from which the fabrics were made, the arrangement and the quality of the working technique (fabric, treatment/canvas preparation).

The degree of degradation, the vulnerability of the material resistance depending on the thickness and the quality of the microfilaments, and the sensitization by the biological action were noted.

After the microscopic examination of the fibers, it was found that the fabrics contain fibers of different sizes in their structure (**Figures 13a–d**).

#### **Figure 12.**

*Heritage*

**No. Samples (biological analyses cods)**

1. P17 Rd 1 Red pigment 2. P17 Wh 2 White pigment

5. P17 Tx 5 At the back of the canvas

10. P10 Tx 5 At the back of the canvas

6. P10 Rd. 1 Scarlet pigment 7. P10 Wh 2 White-gray pigment

11. P13 Rd 1 Red pigment 12. P13 Wh 2 White-gray pigment 13. P13 Bk 3 Matte black pigment 14. P13 Br 4 Dark brown pigment 15. P13 Tx 5 The back of the canvas 16. P7 Wh 1 White, light blue pigment

17. P7 Bu 2 Blue pigment

19. P7 Bk 4 Black pigment 20. P7 Tx 5 The back of the canvas

**Features**

3. P17 Bk 3 Black pigment near the wooden frame (bottom right) 4. P17 Bk 4 Black pigment near the wooden frame (top right)

8. P10 Bk 3 Black pigment—near the wooden frame (bottom right) 9. P10 Bk 4 Black pigment near the wooden frame (top left)

**230**

**Table 1.**

the culture plate.

*2.2.2 Indoor airborne microbial exposure assessment*

*Codification of biological samples and the characteristics of the sampling surfaces.*

The air microbiota is influenced by a number of factors: altitude, season, human

Indoor airborne microbial quantifications are a significant parameter to evaluated healthcare-associated infections. Also, the microbial monitoring accounted for microclimate quality and helped to identify critical situations that require corrective intervention [20]. The level of temperature and relative humidity are favorable

Bacterial and fungal contamination was identified at all airborne microorganism's assessment points. The most diverse contamination was found in the small room where the paintings in the collection were stored for evaluation. The large number of bacterial colonies belonging to the same species of gram + bacilli was found in sample Ae3, (**Figure 12**), the colonies having invaded the entire surface of

agglomerated, degree of ventilation, temperature, and relative humidity.

18. P7 Gr 3 Green pigment with traces of depigmentation

21. Ae 1 Sample 1, centrally located in small room (1-m distance from painting pieces) 22. Ae 2 Sample 2, exhibition, large room (0.5- to 1-m distance from painting pieces) 23. Ae 3 Sample 3, exhibition hall, centrally located on the tourist route 24. Ae 4 Sample 4, small room, near the wall area (1-m distance)

conditions for interspecific changes and to the vector spread [19, 21].

*Microbial isolated stains after 15 minutes exposure of cultures plates to airborne microorganisms in the exhibition area.*


**Table 2.**

*Micro-structural details of fabrics correlated with the level of microbiological contamination.*

Particular aspects such as knotted filaments, and the wrinkled or degraded appearance of the textile micro-structures/fibers, have been observed (**Table 2**).

Microbiological contamination is dissimilar as most bacterial colonies (21 and 14, respectively) were isolated from canvas surfaces P17 Tx 5 and P10 Tx 5, including hemolytic forms. Microbiological contamination with bacteria is more limited in P13 Tx 5. Also, in P7-Tx5, fungal strains with very fast growth capacity such as filamentous ascomycetes were isolated (**Figure 13** and **Table 2**).

The variances that appear regarding the identified colonies are due to the fact that, in such situations, the purity of the fibers, the primer level of animal origin, and the organic or inorganic pigments used influence the process of contamination.

Cellulose filaments with higher purity compared to those with lignin content are more vulnerable to bacteria, a fact confirmed by the larger number of colonies isolated from P17 Tx 5 compared to the other samples.

#### *2.2.4 Painted surfaces*

The assessment of the state of the painted areas in relation to biodegradation took into account the identification by means of the technique of isolation of the microorganisms by culturing techniques and the comparison of the manner in which the areas of the canvas colored with different pigments were contaminated. Thus, the analyzed surfaces were colored with red, white, light blue, green, and black brown pigment. The working hypothesis is the possibility of a difference of contamination correlated with the origin/structure/chemical component of the analyzed pigment. The presence of heavy metals in certain pigments could ensure a resistance of the painted layer [22].

Also, the microorganisms present on the painted surface were assessed by comparison with those isolated from the air microflora in order to determine if this microflora is the main source of contamination or if these paintings have acquired particularities regarding the biodegradation activity due to the substrate or the previous conservation environment.

The identification of the types of microorganisms would allow to establish the methods of decontamination taking into account the following aspects:

**233**

**Figure 14.**

*Microbial diversity and the comparative number of colonies (CFU/cm<sup>2</sup>*

*Technical - Experimental Methods Used in Artworks' Expertise*

The results of the assessment of contamination of painted objects reveal the

• In the large exhibition space (Ae 3), there are some differences between the isolated strains of the air and those isolated from the painted surfaces, a single species of the genus *Aspergillus* having been identified on the painted surfaces

• The direct exchange between the environment microflora and the painting microflora was evident through the analysis of the air a few centimeters away from the painted surface (Ae 2) where in the environmental sample the same fungal species were found (*Aspergillus*, *Penicillium*, *Ascomycetes*) and one very common species of bacteria from the group *Aeromonas* sp. was present on the

The microflora samples collected from the small precinct (Ae 1, Ae 4), with a varied number of paintings with different types of substrates, highlight a large number of common species in the air samples with those found on the painted

• The bacterial forms dominate the painted samples as regards the number of colonies as well as the number of species: *Aeromonas* sp., *Corynebacterium* sp., *Micrococcus* sp., and *Bacillus* sp. The species of the genus *Bacillus* present in our samples are indicated in the literature as predominant, competing species of other bacterial types, frequently isolated from oil painted surfaces. Some *Bacillus* strains show a high level of tolerance to the oils used in the paintings [22].

• The presence of bacteria on the painted surfaces indicates significant differences between the areas with pigments of different paintings as well as from one surface to another on the same painting or the same pigment (**Figures 14a–d**).

*surfaces with different pigment substrates; Rd (red), Wh (white), Bk (black/brown), Gr (green), Bu(blue)* 

*and the convas (Tx 5) samples; a) P17 painting, b) P10 painting, c) P13painting, d) P7 painting.*

*) and species isolated on the painting* 

*DOI: http://dx.doi.org/10.5772/intechopen.92682*

following aspects:

as well.

wall painting as well.

surfaces that were analyzed.

the chemical composition of the oils used; species that produce biodegradation; the response of species of microorganisms to biocides; growth speed.

#### *Technical - Experimental Methods Used in Artworks' Expertise DOI: http://dx.doi.org/10.5772/intechopen.92682*

*Heritage*

**Table 2.**

Particular aspects such as knotted filaments, and the wrinkled or degraded appearance of the textile micro-structures/fibers, have been observed (**Table 2**). Microbiological contamination is dissimilar as most bacterial colonies (21 and 14, respectively) were isolated from canvas surfaces P17 Tx 5 and P10 Tx 5, including hemolytic forms. Microbiological contamination with bacteria is more limited in P13 Tx 5. Also, in P7-Tx5, fungal strains with very fast growth capacity such as

**Samples General aspects of painting canvas Count of isolated** 

P 13 Tx 5 Large mesh fabric, uneven; coarse filaments with knots 6 bacterial colonies

P 17 Tx 5 Compact fabric, without inter-nodular spaces; uniformly arranged, fine, equal thickness, rounded filaments

P 10 Tx 5 Uneven fabric with inter-nodular spaces and irregularities;

P 7 Tx 5 Fabric with filaments of different thickness, wrinkled, with

appearance

degraded appearance

filaments of variable thicknesses and shapes, with lamellar

*Micro-structural details of fabrics correlated with the level of microbiological contamination.*

**microorganisms**

21 bacterial colonies (3 species)

14 bacterial colonies (4 species)

(4 species)

2 fungal colonies

The variances that appear regarding the identified colonies are due to the fact that, in such situations, the purity of the fibers, the primer level of animal origin, and the organic or inorganic pigments used influence the process of contamination. Cellulose filaments with higher purity compared to those with lignin content are more vulnerable to bacteria, a fact confirmed by the larger number of colonies

The assessment of the state of the painted areas in relation to biodegradation took into account the identification by means of the technique of isolation of the microorganisms by culturing techniques and the comparison of the manner in which the areas of the canvas colored with different pigments were contaminated. Thus, the analyzed surfaces were colored with red, white, light blue, green, and black brown pigment. The working hypothesis is the possibility of a difference of contamination correlated with the origin/structure/chemical component of the analyzed pigment. The presence of heavy metals in certain pigments could ensure a

Also, the microorganisms present on the painted surface were assessed by comparison with those isolated from the air microflora in order to determine if this microflora is the main source of contamination or if these paintings have acquired particularities regarding the biodegradation activity due to the substrate or the

The identification of the types of microorganisms would allow to establish the

methods of decontamination taking into account the following aspects:

filamentous ascomycetes were isolated (**Figure 13** and **Table 2**).

isolated from P17 Tx 5 compared to the other samples.

*2.2.4 Painted surfaces*

resistance of the painted layer [22].

previous conservation environment.

the chemical composition of the oils used; species that produce biodegradation;

the response of species of microorganisms to biocides;

**232**

growth speed.

The results of the assessment of contamination of painted objects reveal the following aspects:


The microflora samples collected from the small precinct (Ae 1, Ae 4), with a varied number of paintings with different types of substrates, highlight a large number of common species in the air samples with those found on the painted surfaces that were analyzed.


#### **Figure 14.**

*Microbial diversity and the comparative number of colonies (CFU/cm2 ) and species isolated on the painting surfaces with different pigment substrates; Rd (red), Wh (white), Bk (black/brown), Gr (green), Bu(blue) and the convas (Tx 5) samples; a) P17 painting, b) P10 painting, c) P13painting, d) P7 painting.*

The identification of bacteria on the surfaces of the analyzed paintings, as the dominant forms and the absence of these in the air samples, denotes the presence of organic materials on the surface of the paintings, which maintain bacterial activity. Most likely, this microbial load came from the previous storage of the art collection in noncompliant spaces and from a layer of dust that favored these deposits.

Our observations allow us to ascertain that the exchanges between the painted works and the aeroflora can be favored by the position of the painting in relation to the areas with high tourist traffic, in relation to the distance from the floor and to the variations of the conditions of temperature and humidity.

Depositing the paintings in a crowded manner in small enclosures with insufficient ventilation, without air conditioning, favors contamination between paintings; thus 8 bacterial and 3 fungal species were identified as being shared among the analyzed paintings, out of a total of 14 isolated morphotypes.

The identified fungal strains include *Penicillium* sp. and *Aspergillus* sp., which are known in the literature [23] as factors in the deterioration of the layers painted with oil or of the areas of the paintings treated with adhesives. The growth of these hyphae on the support material (canvas) on which the painting is applied favors the friability and the loss of the painted layers.

Bacteria associated with painted surfaces can form a characteristic biofilm depending on the age of the painting and the working technique (the nature and condition of the painted surface, the degree of maintenance, etc.).

The smaller number of species identified on the canvas (back side) compared to painted surfaces allows important valuations regarding the state of prior preservation of the analyzed paintings.

The presence of colored spores and the production of specific metabolites can produce pigmentation induced by organic acids, which generate major changes in the painted structure, which cannot be repaired.

## **3. Conclusions**

The instrumental and experimental methods of analyzing the works of art belonging to the sixteenth, seventeenth, eighteenth, and nineteenth centuries, to different schools of painting namely Russian, German, and French, purchased from the art collector Catalin Lazureanu, through ARHEOCONS project and recently exhibited in the "Etta Ionescu" Art Gallery of the Ovidius University of Constanta, hosted by the National Military Museum "King Ferdinand I" in Constanta, have been used to establish the following aspects: attribution to the school or the author, the age of the paintings, the preservation mode, the quality and condition of the painted or support materials, the effects of biological contamination, and the severity of biodegradation.

The original provenance and the previous conservation mode have put their mark on the works of art. Identified species, *Aeromonas* sp., *Corynebacterium* sp., and *Micrococcus* sp., as well as the identification of hemolytic forms suggest contact with the dusty spaces of the deposits. The dust particles can not only act physically or chemically but also be sources of infection of the works of art with fungal spores, bacteria, and insect eggs. Microorganisms can reach the art objects, colonizing them, as they have as source of food the organic particles that enter the components of dust and, are favorable for development in an atmosphere with relatively high humidity.

**235**

*Technical - Experimental Methods Used in Artworks' Expertise*

environmental factors, from the exhibition space that can create the risk conditions for the analyzed paintings. The results can be associated with the intervention methods for expertise as well as those related to conservation and/or restoration. Following the study, it can be seen that all paintings require special conditions for conservation. The degradation process can be stopped by measures correlated with limiting the microbiological loading of the air and the painted or supporting components, repositioning the paintings in the exhibition areas without risk of contamination, cleaning the paintings, and restoring the dam-

The study was approached according to clinical health methods analyses, results,

personalized treatment, and principles that the ARHEOCONS project follows

This work was supported by a grant of the Romanian Ministry of Research and Innovation, CCCDI—UEFISCDI, project number PN-III-P1-1.2-PCCDI-2017-

0476/51-PCCDI/2018, within PNCDI III, ACRONIM: ARHEOCONS.

*DOI: http://dx.doi.org/10.5772/intechopen.92682*

regarding the cultural heritage expertise.

The authors declare no conflict of interest.

Special thanks for consulting to Mr. Costel Coroban.

aged areas.

**Acknowledgements**

**Conflict of interest**

**Thanks**

The study allowed new hypotheses on the authenticity of the paintings, to attribute the works to the author or to the school of painting, to identify the

*Technical - Experimental Methods Used in Artworks' Expertise DOI: http://dx.doi.org/10.5772/intechopen.92682*

environmental factors, from the exhibition space that can create the risk conditions for the analyzed paintings. The results can be associated with the intervention methods for expertise as well as those related to conservation and/or restoration.

Following the study, it can be seen that all paintings require special conditions for conservation. The degradation process can be stopped by measures correlated with limiting the microbiological loading of the air and the painted or supporting components, repositioning the paintings in the exhibition areas without risk of contamination, cleaning the paintings, and restoring the damaged areas.

The study was approached according to clinical health methods analyses, results, personalized treatment, and principles that the ARHEOCONS project follows regarding the cultural heritage expertise.
