The University of Texas

San Antonio River Walk Project

[ Project Background | Evaluation of Materials | Documentation | Conservation Treatment | Scanning | History of the River Walk]

Project Background

The Robert H. H. Hugman collection was given to the Alexander Architecture Archive in 1983. The Collection is composed of 62 working drawings of the San Antonio Riverwalk, dating from 1938 to 1940. These drawings represent the work of architect Robert H. H. Hugman, who conceived the original idea for beautifying and stabilizing the flood-prone banks of the San Antonio River in the late 1920's, and who oversaw the first phase of construction after funding became available in 1939. In 2006, the Archive received a grant to create an authoritative website about the Riverwalk, using the drawings as its centerpiece. In order to make the drawings available online, high-resolution digital scans of the drawings would need to be made. But before the scanning process could begin, the drawings needed to be evaluated in terms of physical condition, and in some cases stabilized in order to withstand the rigors of scanning. Also essential was the creation of metadata, the key information about each drawing that would not be readily available from the scan itself. This phase of the project was undertaken by two conservator students at UT's Kilgarlin Center for the Preservation of the Cultural Record, Brenna Campbell and Fletcher Durant.

Brenna Campbell at work.Fletcher Durant at work.

For more information about the River Walk, see The History of the San Antonio River Walk

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Evaluation of Materials

The drawings range in size from very small (10 1/4" x 17 1/16") to very large (30" x 77"). They are in two main formats: ink on linen (for large, durable working drawings), and graphite on tracing paper (for highly detailed work). Both types of drawings have generally stood up well over the years, although some tears and stains have occurred. The primary obstacle to scanning the drawings was the presence of sticky adhesive residue from tape once used to mount the drawings on cardboard.

Linen mounted on cardboardClose up of tape carrier and adhesive

This residue not only makes the drawings difficult to use and store, but has also resulted in staining. Some of the drawings have tears and other damage that probably resulted from frequent handling over the years and, in some cases, removal from the cardboard backing.

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Fletcher taking before treatment photographs.

In all conservation treatment, it is essential to keep accurate written and photographic records of the damage, the techniques used, and the appearance of the object before and after treatment. Each drawing was photographed individually before treatment, and detailed close-up photos were taken of stains and tears. All techniques used were recorded with step-by-step written instructions, as well as photographs of the process. A written description of the entire treatment, known as a ?treatment report,? along with photodocumentation, is available here.

In addition, metadata was collected prior to scanning in order to document information pertaining to each drawing such as the date of creation, title, and contents. That information can be downloaded here.

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Conservation Treatment

Bench set up prior to treatment.

The first step in treatment was to remove the sticky adhesive residue from the backs of the drawings. Beginning with the ink drawings on heavily-starched linen cloth, the materials presented a special challenge because of their size and the large number of glue spots (sometimes up to 12 on a single drawing). Testing of the adhesive with several different chemical solvents proved ineffective. A process was developed in which the adhesive spots were gently heated to soften them, after which they were covered with alpha cellulose, a fluffy, white powder designed to absorb some of the glue and make it less sticky. The glue spots were then carefully scraped away with specially modified metal tools. If necessary, this process was repeated several times. Any remaining adhesive residue was removed with a white plastic eraser, and the spot was dusted clean with a soft brush.

Mechanical removal of adhesive with a microspatula.Adhesive residue after mechanical removal.Blobs of removed adhesive residue.Removing remaining adhesive with an eraser.

The adhesive residue on the tracing paper drawings created a different set of challenges. Scraping the adesive by hand was not an option due to the fragility of the paper. Fortunately, a different adhesive tape had been used on these drawings, and a solvent was found that would dissolve this adhesive; however, it produced fumes that could be harmful to the conservators. Therefore, the drawings had to be treated one at a time inside a fume hood that removed and filtered the chemical vapors. The solvent was carefully applied to the sticky areas with a cotton swab. Unlike the removal procedure for the linen drawings, this process also reduced the staining and resulting disfiguration of the drawings. After this treatment the drawings were ready to be mended (if necessary) and scanned.

Using solvents in a fumehood to remove adhesive from tracing paper.Brenna using solvents in the fume hood to remove adhesive.Solvent appliacation with a cotton swab.

The linen drawings were no longer sticky, but they remained discolored and translucent where the adhesive had been. Although these stains occurred primarily in the margins of the drawings, they were still considered to be distracting. Through testing, a combination of solvents was found that would dramatically reduce the translucent, ?oily? quality of these stains, and minimize the brown discoloration. This solvent mixture had to be applied to the stains and allowed to sit for several minutes. Like many solvents, this mixture was prone to very quick evaporation. In order to keep the solvent in contact with the stain long enough to reduce the discoloration, a technique was devised in which pieces of blotter (a very soft, absorbent type of pure cotton paper) were cut to exactly the size of the stain. The blotter was sprayed with the solvent mixture and placed on either side of the drawing, atop the stain. Then, the sandwich was covered with a glass weight and left undisturbed for 10-15 minutes to allow the solvent to reduce the staining. This technique allowed the conservators to treat all of the stains on a drawing at one time, and minimized the amount of solvent mixture used. The disadvantages of the technique were that it required the use of solvents outside of a fume hood, and that it created ?tidelines? around the stain. To mitigate these problems, the conservators wore special respirator masks with air filters to protect themselves against exposure to the fumes, and reduced the tidelines by applying the same solvent mixture with a small brush and blotting.

Using solvents to reduce stains.Tide-lines from stain reduction.Manually reducing tide-lines.A reduced stain.

After stain reduction, the drawings were ready to mend. Because the tracing paper drawings were thin and fragile, any moisture introduced while mending would cause the paper to cockle and distort. A special mending tissue was made by applying a very thin layer of heat-activated adhesive to the back of a light weight Japanese tissue paper. This heat-set tissue was then torn to the appropriate size and shape, and carefully applied over the tears with gentle heat. In order to make the mends less visible, they were done on the backside of the drawing.

The linen drawings were mended with a slightly heavier Japanese tissue paper and a cooked wheat starch paste, and allowed to dry under weight.


Due to limited funding, only a select few of the most interesting and attractive drawings were actually scanned. These images were scanned by UT Library?s Digital Library Services at a resolution of 300 dpi. If you are interested in ordering uncompressed copies of these images, please contact the Archives.

Click on the thumbnails for a larger image.

Trace paper drawing of the Plan above Weir.

Linen drawing of Plan For San Antonio River From Houston St. South to Channel Cut-Off.

Trace paper drawing of Plan for Change in Cantilever.

Trace paper drawing of assorted details.

Linen drawing of assorted details.

Linen drawing of assorted details.

At this time, no additional images of these drawings are available. However, the drawings have been stabilized and can be readily scanned at a future date, should more funding become available.

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