The most expansion for any thickness and at any tack profile is when the stack is placed at the edge. The further away from the edge, the less the expansion. There is no noticeable expansion of size when the tack stacks are placed 20mm from the edge. In most cases there is only a little expansion at 10mm from the edge. Although not tested, it seems that 15mm is a safe distance from the edge to avoid changing the edge.
The amount of glass in the stack being tacked to the base has an effect on the amount of expansion. This is to be expected based on the concepts behind volume control. Two tack layers can vary from two to three times that for a single tack layer depending on the profile of the tack.
The tack profile has an effect on the amount of expansion. At contour there is a greater expansion than at rounded or sharp tack fuse. This is to be expected, as there is less heat work at sharper tack profiles than at contour.
The thickness of the base has an influence on the amount of expansion too. Thicker stacks promote greater deformation of the edge at all tack levels. Thicker stacks need to be placed further from the edge to avoid changing the perimeter. Thicker stacks create greater change in the edge on single layers than double layers.
Setup for 2 layer base and 1 and 2 layer stacks at various distances from the edge. |
Contour fuse test, 6mm base
1 layer placed at edge, at 10mm from edge, at 20mm from edge, and at 30mm from edge. 2 layer stacks placed in the same way.
Fired results, outlined for clarity |
1 layer placed 10mm from edge – expansion of 0mm
1 layer placed 20mm from edge – expansion of 0mm
1 layer placed 30mm from edge – expansion of 0mm
2 layers placed 10mm from edge – expansion of 2mm
2 layers placed 20mm from edge – expansion of 0mm
2 layers placed 30mm from edge – expansion of 0mm
1 layer placed at edge, at 10mm from edge, and at 20mm from edge.
2 layer stacks placed in the same way.
1 layer 10mm from edge – expansion of 0mm
1 layer 20mm from edge – expansion of 0mm
2 layers placed 10mm from edge – expansion of 1mm
2 layers placed 20mm from edge – expansion of 0mm
Fired result of 6mm base with 1 and 2 tack layers, rounded tack. |
1 layer placed at edge, 1 at 10mm from edge, 1 at 20mm from edge, 1 at 30mm from edge. 2 layer stacks placed as above.
1 layer 10mm from edge – expansion of 1mm
1 layer 20mm from edge – expansion of 0mm
1 layer 30mm from edge – expansion of 0mm
2 layers 10mm from edge – expansion of 1mm
2 layers 20mm from edge – expansion of 0mm
2 layers 30mm from edge – expansion of 0mm
Fired result of 3mm base with 1 and 2 tack layers. |
1 layer placed at edge, 1 at 10mm from edge, 1 at 20mm from edge, 1 at 30mm from edge. 2 layer stacks placed as above.
1 layer 10mm from edge – expansion of 0mm
1 layer 20mm from edge – expansion of 0mm
1 layer 30mm from edge – expansion of 0mm
2 layers 10mm from edge – expansion of 0mm
2 layers 20mm from edge – expansion of 0mm
2 layers 30mm from edge – expansion of 0mm
Thank you so much for your research and published results about expansion of tack fused stacks. This is very helpful, especially for novices.
ReplyDeleteI appreciate all your advice and am grateful for your generousity in sharing your knowledge.
Just this week I met another glass artist near where I live. Jan too is generous with her years of experience.
Happy and healthy New Year to you Stephen.