I have found that these chips (bark) do tend to go mouldy and black I have removed and replaced which can be an expensive job try stone this will last a lot longer and is easier to clean most diy/garden suppliers sell attractive stone also consider some kind of decking scheme we did our a few years ago and love it

Steveg - the chips James is referring to were white stone chips, not bark.
Jamespaul, it would have been better to add this underneath your original question, as if you're answering yourself, if you get my drift.
It was me who answered previously - I'm not sure what you could use that won't discolour in a similar way - gravel tends to be better because you can rake it over periodically, and it doesn't seem to get black like the coloured chippings, although all the loose stone products are better in a good amount of sun. Black chippings or slate at least wouldn't show the discoloration so easily. Otherwise, its hard paving or bark chips.

Agree with Bamboo

We have white marble chips and part crushed slate and has not discoloured.

Are they in shade under a tree Scotkat, that is where the problem lies.

Did you mean 'stone' chips? Not aware you said stone or bark. Please clarify jamespaul. Thank you so much.

White stone chips this is James' second posting of the same Q

Would a moss remover help? Products with iron would stain the marble red, though. We use a 2% solution of white vinegar to kill the moss and algae, here, but our soil is naturally alkaline, so it benefits from that. I don't know what would happen in acid soil. Maybe the marble would neutralize it enough.

"my chips being very dirty "

Peel the potatoes before you fry them!

;^)

For clarification, Avkg47, see my response (2nd from the top)

Tug, would the vinegar solution work for lichen? My patio looks as if hoards of kids have been dropping their bubble gum on it.

I don't know, Steragram! It might be worth a try.

Thank you, Bamboo, and MG, though reading both questions he didn't actually say stone ... sorry to assume he meant white, ie raw, wood chips ... simple mistake!! Anchorman ... you have an excellent sense of humour! What about jeyes fluid for outdoor use? Know little about its effect on plants, but does wonders for cleaning paths etc through the garden??

Jeyes fluid and plants are not a good combination.

Lemon juice? How big is the area, jamespaul, and as MG asks, are they under a tree or shrub of any kind? Aphids of all sorts produce a sticky or sooty black substance that could be landing on your stone chips. If you have shrubs above with 'soot' on their leaves then you need to spray with ultimate bug killer?

If the chips are under conifers, resin will attach to them and attract dirt - also, other deciduous trees such as lime produce sticky drip in summer, causing the same trouble.