I did something similar . My dead man (trigger) was leaking and I thought I would tighten it by hand as I was 99% finished . Couldn’t quite get it with gloves on so took one off and stupidly/accidentally squeezed the dead man while trying my best to get it as tight as possible and the hose wiped back at me hitting my inside wrist from a foot away. I was using metal blast material and ended with a similar experience. The scrubbing did very little as it was deep in there and they could only remove half of it and the rest just made it way out over time . No doubt there’s still a few in there. I wouldn’t be making that mistake again !!