Try putting it in the compost heap instead, and keep it off raspberries as well as azaleas etc. Don't use it at all if it has any coal or coke residue in it.

It's quite good for onions, but I wouldn't be using it generally round the garden (even if its wood ash - the potash content, depending on the wood burnt, can be negligible anyway, but it does have a fairly significant alkalising effect, as you've discovered).

Thats interesting Bamboo - do you know which woods are high/low in potash?

The great Harry Dodson on Wartime Kitchen and Garden used neat wood ash on his tomatoes and they were fantastic. You can use it around any non-ericaceous shrub, mix it with garden compost or leaf mould if you think your soil is already too alkaline.
All wood ash will contain essential minerals, the proportions may vary slightly but there will be potassium in all. It is partly in the form of potassium oxide when dry, hydroxide when wet and then carbonate after exposure to air for a few hours. This may be very alkaline but so mobile it won't have a long-term effect on soil pH.

There you go, Steragram...!

Will carry on doing what I was doing hten! Thanks all.

Thanks to all for those replies. Should I water it in? And is it ok to mix in with well-rotted horse manure?