There is already a lot of discussion on blacking up within the morris world. The origins are unclear, and some attribute its origins to minstrelsy although there seems to be some limited evidence of earlier blacking-up.

I'm inclined to think that blacking up was part of morris and other traditions before minstrelsy. Minstrelsy was an huge part of popular culture for a long period and it would be remarkable if it did not have an influence on existing traditions as well as spawning new ones. However, whilst Cotswold morris, to take one example, adopted many minstrel tunes it did not adopt blacking-up. This suggests to me that minstrelsy merely reinforced those traditions such as Border where blacking-up was already part of the custom, rather than being the origin of the practice. However this is pure hypothesis on my part.

I don't think morris need be ashamed of the practice, although there are good reasons in our modern more multi-cultural society to consider whether it should continue. Many modern morris sides have made the decision to use different colours to avoid giving offence. Others take the view that there is nothing else in the tradition to suggest that black people are being imitated, let alone ridiculed, and that it is important to preserve our customs against political correctness. I think both attitudes are deserving of respect provided they have been arrived at after careful consideration.