Here is the core of his thought :
Personally I think it improbable that blood could survive relatively intact – ie. as a porphyrin-iron complex linked to a globin protein – for more than a century or two unless kept in very dry air (as is presently the case). Alan Adler’s findings spoke of highly denatured, at least partially-chemically degraded rather anything remotely representing native blood.
Fungi and bacteria would gradually degrade the blood, the latter representing a rich balanced source of nutrients. Even in “dry” rain-proof garages one can see spots of black or even pink mildew forming on one’s decorating cloths – there’s enough moisture in air to permit the growth of cellulase-secreting fungi – ones that gradually break down tough cellulose fibres. Imagine how much easier it must be to effect biodegradation of proteins, sugars etc as exist in whole blood.
As he wrote proteins are much more fragile than porphyrins (heme).
But despite this fact, Collin apparently does not know that blood proteins on archaeological artifacts (mainly stone tools) are now widely studied using immunology.
Not only on centuries-old artifacts but on artifacts older than 10000 years BP.
Not only on clean artifacts "kept in very dry air" but found in contaminated soils
And more amazing is the fact that the researchers are able to provide species-specific signatures.
A good example among many others can be found here:
http://www.sciencedirect.com/science/article/pii/S0305440308001003
For a good synthesis (google books) :
http://books.google.fr/books . . . [ edited and relinked with http://tinyurl.com/cphhzdr ]
At least, it means that the epitopes (parts of the proteins involved in the antigen-antibodies reactions) are still intact after thousands of years.
I will answer to some other claims of Collin regarding blood later.
Excellent response.