Piston Slap - Does this cause damage?

Cheers 19
Apologies - I should have updated my post about the carbon on plugs - I think I'd seen that due to short runs.. they now look a nice 'grey' .. I thought they should be tan also but a video on mikes carbs site says grey is correct .. ??.. they always used to be tan in the 80's when leaded was about .. maybe the tan is something to do with the lead . ...?.. I do put castrol additive in though.

Really sorry if that's negated your post.
DO really your time either way
Thanks
D

Not sure what the etiquette is on reviving old posts but I am bring this one back.

After reading through this I found exactly what was causing my engine knock at start up. It was running rich for a while and all that carbon caused the knock until the engine was warm. I used some Seafoam and Lucas oil lubricant on a fill up and the knock is almost completely gone. I will probably add another round of Seafoam along with a long drive and that should clean the rest of the gunk out.

Not sure how I would of figured it out without this forums awesome search function! Thanks guys!

some use "Techron"
obtainable in Wally's World and other big box stores (autzone, etc).