Hi dodgyfolk,

As the tambourines were made in a dry environment they will always be slack even in the average 45% humidity of the UK (can be a lot more on occasion).

This is what I would do. Purchase some fine thin (c. 1cm) leather strip of a suitable colour from a haberdasher's suppliers. As you untack the heads, glue this over the tack holes with a flexible and compatible adhesive (a thin layer of animal glue would be best but Copydex would probably also work). Once removed, soak the skins for half an hour in warm water. While still damp, stretch them (not too tightly) over the frame and retack on through the leather strip). As they dry they will naturally tighten. Once dry, a sparing application of tallow, lanolin or neatfoot oil once a year will be advantageous in keeping the skin supple (water vapour will still affect the skin to a certain extent).

Note! There is a bit of an art to getting the tension right when stretching. However, I have repaired or adjusted several bodhrans like this (including my own ...damn! I've admitted owning one!) with good results.

Peace

moo