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For this activity, the building was divided in four main areas, the façades of Andes Street, 18 de Julio Avenue, Plaza Independencia and the Gallery (Figure 2). A total of 675 pieces were analysed. The basis used for this diagnosis is the classification proposed by ICOMOS (2011).

Table 4: Deterioration features present in Pilasters and Columns of Palacio Salvo (in brackets number of pieces with feature repaired).

Deterioration	Andes	18 de Julio	Gallery	Plaza Independencia
Crack	10	6	8	14
Star crack	2	1	0	3
Blistering	0	0	0	1
Bursting	1	0	0	0
Splintering	23	11	0	0
Chipping	8	8	3	8
Spalling	0	0	0	2
Differential erosion	0	0	0	3
Rounding	98	20	59	64
Impact damage	0	0	0	1
Cut	5	0	0	1
Scratch	0	0	1	1
Missing part	22 (18)	30 (19)	21 (4)	52 (4)
Gap	1 (12)	0	0	0
Perforation	3 (35)	4 (18)	7 (20)	2 (20)
Perforation with plastic	7	1	0	2
Pitting	0	0	0	4
Metallic insert	55 (2)	10 (4)	42 (14)	44 (12)
Strange Element	3	12	27	31
Dust Deposit	4	0	0	0
Paint	97	43	130	94
Stick	42	15	73	92
Cement	8	2	18	14
Grease	22	21	7	0
Pigeon Dropping	5	6	8	72
Bleaching	0	0	0	2
Oxide staining	18	0	32	49
Film	10	0	0	0
Graffiti	11	1	4	0
Patina	14	9	19	28
Soiling	6	21	74	103
Spider net	1	2	2	4
Pieces analysed	153	67	171	218

The five deterioration families of this framework are present in Palacio Salvo (Tables 4 and 5). The Family Crack and Deformation is represented mainly by cracks and star cracks (Figure 3). Cracks occur very seldom in pilasters and columns, and only one is present in a step (Tables 4 and 5).

Splintering is the most frequent deterioration feature of the Family Detachment observed in Andes Street and 18 de Julio Avenue, followed by Chipping, which affects pilasters and columns of the four areas studied (Figure 4). Due to the location and characteristics of the latter features, they are a product of differential movement of the structure or the masonry, and not originated from low resistance of the rock. They are absent in steps.

Fragmentation is only observed in two panels of the Gallery. Blistering and spalling are related with features of other families and will be discussed at the end of the section.

Table 5: Deterioration features present in steps of Palacio Salvo (in brackets number of pieces with feature repaired).

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Figure 4: a. Splintering, chipping, paint film, perforation and perforation with metallic insert in pilaster of Andes Street, b. Splintering with development of two parallel fractures.

Figure 5: Soiling in inner faces of Plaza Independencia columns: a. Partially “washed out”, b. Rock without deterioration beneath partially eroded soiling.

Features induced by material loss is the second most represented family, being rounding, perforation and missing part the ones which affect the higher number of pilasters and columns. Many perforations present metallic inserts, which causes very frequently oxide staining leading eventually to bursting (Figure 3). In the steps, rounding affects almost all pieces, abrasion and missing part a quarter of them.

The most represented family is Discolouration and deposit. Six subtypes of deposits are very frequently observed (dust deposit, paint, stick, cement, grease and pigeon droppings) in pilasters, columns and steps. Patina is frequent in small areas of the pieces. Soiling is very frequent in inner areas of pilasters and columns of the Gallery and Plaza Independencia, sheltered from rain and wind (Figures 5 and 6).

A deterioration association is observed in two felsic enclaves up to 40 cm in two faces of a highly exposed column of Plaza Independencia. The association includes bleaching, pitting, blistering, spalling and differential erosion, and is more advanced in the enclave which is frequently exposed to dog urine. This association is presumably related to the action of SO₂ product of air pollution, that causes feldspar kaolinsation and possible salt formation, as described by Schiavon (2007). Family Biological colonization is only represented by very seldom spider nets.

Other alterations are modification of the original basement ventilation elements, in Andes Street, 18 de Julio Avenue and Gallery. Most of them were transformed to access steps to business, which originally had no exterior access. These steps are made up of other rocks (Pan de Azúcar Syenite due to the similarity in décor) or monolithic (Table 5). Other category is “Strange elements”, including commercial posters, door numbers, etc.

A map of a column of Plaza Independencia is presented in figure 6. View I faces Plaza Independencia and is exposed, and View III faces the Gallery and is sheltered from rain and wind.

Figure 6: Deterioration map of Column 6 of Plaza Independencia (modified from FADU, 2019).