I have tried this myself, and can safely say, it won't make much difference, if any at all. When the foil is applied, it will have alot of small creases and folds in it which makes it a poor choice for your usage. You may want to try tin or aluminum sheets that have a mirror finish to them.
-Bill J
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Updated list as of: 10/20/03
2.2.3 D. azureus
1.2 D. ventrimaculatus 'yellow' (22 tads in the water)
3.3 D. tinctorius 'cobalt'
0.0.3 D. tinctorius 'patricia'
0.0.1 D. tinctorius 'giant orange'
0.0.1 D. tinctorius 'citronella'
0.0.2 D auratus 'zwartgroene(black)'
0.0.5 D. auratus 'green/black' (tads)
0.0.3 D. imitator 'Alex Sens line' (very soon)
0.0.2 D. reticulatus (soon)