# Varnishes with Biocidal Activity: A New Approach to Protecting Artworks
## 3 Results and Discussion
### Colophony
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Test** & **Sample Type** & **DHA** & **AA** & **7-OH- DHA** & **15-OH- DHA** & **7-oxo- DHA** & **15-OH-7-oxo-DHA** \\ \hline Colophony & 1 & **56.5** & **10.3** & **3.0** & **9.8** & **5.8** & **1.4** \\ Colophony-Cs & 3 & 51.3 & 0.0 & 2.8 & 8.9 & 17.2 & 3.3 \\ Colophony-Ba & 3 & 24.4 & 0.0 & 6.1 & 12.2 & 36.5 & 14.8 \\ Colophony Benzalkonium chloride (sp) Cs & 5 & 57.2 & 0.9 & 3.1 & 6.1 & 9.6 & 0.0 \\ Colophony Tributyltin naphthenate (sp) Cs & 5 & 58.9 & 0.8 & 3.3 & 5.6 & 8.9 & 0.0 \\ Colophony Orthophenyl phenol (sp) Cs & 5 & 56.4 & 11.4 & 1.8 & 5.3 & 3.0 & 0.0 \\ Colophony Benzalkonyum chloride (sp) Ba & 5 & 56.0 & 1.6 & 2.4 & 8.5 & 10.1 & 0.0 \\ Colophony Tributyltin naphthenate (sp) Ba & 5 & 55.7 & 1.0 & 3.1 & 7.3 & 11.7 & 0.0 \\ Colophony Orthophenyl phenol (sp) Ba & 5 & 54.5 & 2.0 & 2.0 & 7.8 & 7.8 & 0.0 \\ Colophony Benzalkonium chloride Ba & 4 & 57.1 & 2.4 & 1.6 & 6.8 & 6.1 & 0.0 \\ Colophony Tributyltin naphthenate Ba & 4 & 43.7 & 36.8 & 1.0 & 4.5 & 0.6 & 0.0 \\ Colophony Orthophenyl phenol Ba & 4 & 53.2 & 11.5 & 1.1 & 3.3 & 0.6 & 0.0 \\ \hline DHA = dehydroabetic acid; AA = abietic acid; 7-oxo-DHA = 7-oxo-dehydroabietic acid; 15-OH-7-oxo-DHA = 15 hydroxy-7-oxo-dehydroabietic acid. Sample type: 1: varnish only (blank samples); type 3: varnish inoculated with microorganisms; types 4 and 5: varnish treated with biocides, mixed (4) and spread (sp), (5) and inoculated with microorganisms. Cs = _C. sitophila_; Ba = _B. amyloliquefaciens_. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: GC-MS analysis (\(p<0.05\) in all cases) of the diterpenes from the colophony varnish and the samples inoculated with microorganisms (values expressed in _Ni_). The exception is the sample inoculated with _B. amyloliquefacients_, the microorganism capable of producing the greatest chemical changes in the colophony, treated with the biocide tributyltin naphthalene mixed with the varnish. The biocide was not seen to be sufficiently effective, but nevertheless it managed to make the composition of the varnish somewhat closer to the blank sample than when it is inoculated with this bacteria type without the presence of the biocide. The results show the efficacy of the treatments tested, and they also resemble those obtained in a previous study carried out by our research group [35] that analyzed the changes produced by microorganisms inoculated in  
Figure 4: Multidimensional scaling (MDS) analysis of the colophony samples: blank sample (type 1, red circle); samples inoculated with microorganisms without biocide (type 3, blue diamonds); and samples inoculated with Cs and Ba, and treated with the studied biocides (type 4 (mix), and 5 (sp), green squares). BC = benzalkonium chloride, TBTN = tributyltin naphtenate, and OPP = ortophenyl phenol. Cs = _C. sitophila_; Ba = _B. amyloliquefacients_. Figure 3: Chromatograms corresponding to (**a**) colophony varnish treated with Benzalkonium chloride and inoculated with _B. amyloliquefacients_ (type 4) and (**b**) colophony varnish not treated with biocides but inoculated with _B. amyloliquefacients_ (type 3). Values expressed in _Ni._ 1: DHA = dehydrodiabetic acid; 2: 7-OH-dehydrodiabetic acid; 3: 15-OH-dehydrodiabetic acid; 4: 7-oxo-dehydrodiabetic acid; 5: 15-OH-7-oxo-dehydrodiabetic acid. colophony resin samples treated on the surface with the biocides New Des (benzalkonium chloride), Biotin N, and Nipagine (methyl parahydroybenzoate). The analyses by pyrolysis-GC-MS showed the efficacy of treatments with Biotin N on the growth of fungi and bacteria, without appreciable changes in the composition of the resins, and a lower effectiveness of the treatment with benzalkonium chloride and Nipagine.