JAIC 2002, Volume 41, Number 1, Article 1 (pp. 01 to 12)
JAIC online
Journal of the American Institute for Conservation
JAIC 2002, Volume 41, Number 1, Article 1 (pp. 01 to 12)

OVERLAY WITH A DIFFERENCE: STRONG SUPPORT-THREAD EDGE FINISH FOR TETEX TR

RENÉE DANCAUSE



8 WORKING WITH THE HEATED SPATULA

When ready to begin hot-melt-cutting the first stitched motif, tape the overlay down to a sheet of Teflon-coated fiberglass that itself is secured to the table surface. The Tetex TR has less of a tendency to shift and bubble if it is taped. Alternatively, the hot-melt-cutting can be done with the Tetex TR unrestrained, depending on individual preference and experience (fig. 7). If using the Teflon, transferring the image tracings to it before the hot-melt-cutting may be helpful.

Polyester melts at 238–90°C (460–554°F) (Hudson et al. 1993). The heated spatula must reach these temperatures and have a narrow, needlelike head capable of making a fine cut in the polyester fabric when heated. Our laboratory has a changeable-head spatula purchased in the 1970s, which has two useful heads for hot-melt-cutting: one resembles a fine needle and is 5 mm (1/4 in.) long; the other is coarser and 7 mm (1/2 in.) long. It appears as though one of these heads was retrofitted in-house. Authors French and Gentle (1993) describe using a pyrograph, a wood-or leather-burning tool with various heads.

“Meld,” a word combining melt and weld, will be used to refer to the hot-melt-cutting process whereby not only is the Tetex TR melted as it is cut but the polyester conforms to the supplementary support thread that itself is intended to stay intact (fig. 8). In order to meld, the needle head is held perpendicular to the table, gliding the head in contact with the Teflon-coated fiberglass. Whether or not the Tetex TR edges are restrained while melding, in both cases the author found that the use of gripping tweezers or needle holders held in the free hand greatly facilitates grasping the freshly hot-melt-cut area and holding it in its required shape until it cools, to maintain curved or multiangular features of design motifs. Also, sometimes it helps to hold the Tetex TR taut, slightly up off the table, with tweezers in one hand while hot-melt-cutting with the other. The side of the pointed spatula head is passed in contact with the support thread, retaining the thread (the Tetex TR melts neatly around the larger thread) to strengthen the melded edge, and it is used as a guide to cut away the unwanted part of the Tetex TR, one small section at a time (fig. 9). Any lingering with the head of the heated spatula will melt the support thread. Melding is stopped every few seconds to enable the area to cool while holding it in the desired shape with tweezers. Cooling is very brief. In between melding sessions, melted polyester is scraped from the needle head with a knife.

Fig. 7. The hot-melt-cutting setup with Teflon-coated fiberglass under the battle honors, the tools needed, a light and extraction unit (clear dome)

Fig. 8. A close-up of the support thread held in place by the hot-melt-cut Tetex TR

Fig. 9. The resulting void in the overlay accommodates the battle honors and illustrates also that the support thread is retained.


Copyright © 2002 American Institution for Conservation of Historic & Artistic Works