Efflorescence from black cement dye?

[George-Stone Gardens]

We laid a black limestone patio for a customer and used a black cement dye in the pointing mix. The paving itself has effloresced (sp?) and now gone back to normal but the pointing actually looks really white now which again is presumably efflorescence as it goes away when wet but its a much stronger effect than the paving had and has been like this for at least 3 months now. Does anyone have any experience with this happening and know how long it might take for the efflorescence to finish doing its thing?

[London Stone Paving]

In my experience Dyes never give the expected result and always seem to dry to a chalky colour. You may be stuck with this colour and there is no chance it will got to the black colour that you originally hoped for

[TheRockConcreting]

Like LSP said black/charcoal pigments never stay dark. Pigments don't take to well with CEM II general purpose cement, always use CEM I 100% PC. Normally manufactures recommend a min of 5% pigment to weight of cement, i would recommend using 8% as a maximum. Try sealing a small area, if its not efflorescence it will go away, and the colour will be much richer.

[George-Stone Gardens]

Yes we plan to seal the paving to keep it looking black but thought it would be best to wait for the efflorescence to stop before doing so, so that it doesn't get trapped under the sealant. I heard back from a rep from the company who made the dye and he said it takes about 6 months to disappear.

Does anyone know if a colour enhancing sealer would make the pointing darker as well?

Otherwise we might have to chip it all out and use a resin system instead