Quote Originally Posted by ccdjg View Post
Many thanks for your very knowledgeable input, which gave me much food for thought. It prompted me to have a look at what Wikipedia says, and apparently there are 8 types of aluminium alloy and only group 7 contains any zinc. Within this group (called the 7000 series) the zinc content averages about 8% and is never more than 11%, so this means that if the LP53 alloy is aluminium based , it should be easy to detect which is the dominant metal by chemical means. On the other hand, zinc alloys containing aluminium can contain up to 25% aluminium, so it would be bit more difficult to sort out the dominant metal chemically.

It seems to me that the best way of sorting this question out is to actually try anodising and blacking a sample barrel. If it is an aluminium alloy, the 8-11% zinc will not interfere much with the anodising process and so a good black finish should be achievable. On the other hand, if it is a zinc alloy with only 25% or less aluminium, there will be virtually no colour take-up , as zinc does not anodise.

As the Walther black finish has all the characteristics of an anodised coating, this almost answers the question, but the proof of the pudding is still in the eating. If Matt goes ahead with an anodising experiment on his barrel and gets a positive result, then this will not only answer the question, but will give collectors a way of restoring their faded barrels with a genuine Walther-type finish.
I would say all groups have Zinc, but 1-6 very little in fact, Wiki is O.K. but you need to click on the series number itself and then read the full spec, as otherwise they just state the main alloying elements.

But really yes, the 7000 group is the only one with a substantial (compared to the trace amount in the lower groups) percentage.

All the above is just tech stuff really, as you say a practical experiment will be far more useful.

ATB, Ed