Thanks Guys!
The product is being flow wrapped so open at infeed and closed on outfeed and yes they are using it on the heat seals. We did buy them a food safe brush which they complained about so I guess as long as its controlled and not left out during production we should be able to satisfy an auditor......
I think you have to follow that BRC classic and risk assess it; yes, you've identified there is a risk but these are the things you've put in place. Document it and audit it as controls like the ones I'm suggesting are easily ignored. Unless you then end up with complaints with pieces of metal coming back you've got a defence for the external auditor.
Might be worth going back to the team and asking what the problem was with the food safe brushes, although the things I've suggested might help prevent a problem, they don't exclude it. That said, as I was indicating earlier, I had a sealing process in one factory which was critical to the shelf life. The team changed the brush spec (without telling me, this was for cost rather than food safety), then changed back quite quickly. It ****ed up the sealing jaws and it took months of investigation to find out why complaints had started to go up. We had to then replace the sealing jaws at considerable expense.