Staples vs Tacks—Canvas Attachments and Strain in Easel Paintings

The study reviewed in this article explains where stress builds in a stretched canvas, how fasteners transmit that load, and how the choice of staples vs tacks affects canvas paintings. Using ESPI strain mapping, the authors link fastener type, spacing, and face placement to cusping, edge tears, and diagonal cracks. The aim is practical: show how to choose and place attachments—and how far apart—to keep strain more uniform.

What the Authors Tested: Staples vs Tacks, Spacing, Placement

The authors built twelve 300 mm square stretchers with butt‑jointed corners. Each had chamfered, bevelled bars. They mounted Ulster linen that was wet‑stretched three times, sized with 1:20 rabbitskin glue, and primed with two knife‑applied coats of lead‑white oil ground [Young & Hibberd, 2000, p. 213]. Configurations included tacks and Arrow T50 staples at 30 mm and 15 mm spacing, front, side, and back face placements, plus lacing. They also ran strip tests and added 2‑ply card beneath some staples [Young & Hibberd, 2000, pp. 213–214, 217–218].

Key Results on Staples vs Tacks and Placement

• Edge attachments create strain troughs and ridges that extend ~40–50 mm into the canvas; visible cusping matches those fields [Young & Hibberd, 2000, pp. 215–216].
• Closer spacing (15 mm vs 30 mm) enlarges the central region of even strain and reduces cusping [Young & Hibberd, 2000, p. 215].
• Side‑ and back‑face attachments smooth the front‑face strain field because stretcher‑bar friction offloads the fasteners (μ≈0.25) [Young & Hibberd, 2000, pp. 217–218].
• Staples act as a bridge until slippage; then load transfers to sharp legs, producing local tearing and very high strain near each leg [Young & Hibberd, 2000, p. 217].
• Tacks restrain effectively and are less prone to tear the canvas in these tests [Young & Hibberd, 2000, p. 217].
• Card under staples spreads the grip and reduces strain concentrations; a continuous strip works best at the tested spacing [Young & Hibberd, 2000, p. 218].
• Tight “hospital” corner folds reduce corner overloads and help prevent diagonal strain bands from keyed joints [Young & Hibberd, 2000, p. 215].
• Laced samples do not show elevated corner strains seen with keyed stretchers [Young & Hibberd, 2000, p. 215].
• Primary cusping forms at stretching; added tension later produces secondary cusping; priming only partly locks the shape in early weeks [Young & Hibberd, 2000, p. 216].

Practical Implications: Staples vs Tacks in Studio Practice

Choosing and Placing Attachments: Staples vs Tacks

Closer spacing reduces cusping and evens strain. Fifteen millimetres worked better than 30 mm in these tests [Young & Hibberd, 2000, p. 215]. Placing attachments on the back face shifts irregularities away from the picture plane and uses bar friction to reduce loads [Young & Hibberd, 2000, pp. 217–218].

Fastener type and margins

Tacks gave good restraint with less tendency to cut fibers. Flat‑wire staples can tear the canvas after the bridge slips. If staples are necessary, choose stainless, round‑leg designs and use stiff card as a load spreader [Young & Hibberd, 2000, pp. 217–218]. Protect original tacking margins whenever possible.

Corners and keying

Make tight, compact corner folds. Avoid aggressive keying that drives high diagonal strains from the corner joints into the paint [Young & Hibberd, 2000, p. 215]. Temporary lacing is still useful during treatment or priming when corner restraint is not desired [Young & Hibberd, 2000, p. 215].

Grounds and timing

Expect secondary cusping if you re‑tension within weeks of priming. Oil grounds need time to lock the deformation [Young & Hibberd, 2000, p. 216]. Condition the canvas and size to a stable RH before any tension changes.