How could I change this splatter from white to a different colour?

Hi

I currently have an area I added with a splatter brush that's white, and I want to add a bit of an orange tint to it. The blend layers aren't really doing the job, and obviously, adding a Hue/Saturation Adjustment Layer has no effect to the white. I have tried selecting the area with the Lasso tool and adding a Solid Colour, but that just fills in the entire selection. Similarly, I can't select the content of the layer to make a mask from it as it says there aren't enough pixels.

Apart from adding the splatter with a different coloured brush, is there any quick trick that will allow me to change the white?

Thanks