I just marbled a rod last night, I would like to add a couple more colors, is it ok to lay the 2 colors over the existing marble without laying another layer of base coat?

When you say without another layer of base coat, do you mean not even a layer of clear? I haven't done a lot of marbling, but without some sort of liquid layer to lay your colors on, you won't get the same effect. I mean you might if you really thin your colors so they'll run more, but I'm thinking you would at least need a coat of clear?

If you add another base coat, you'll cover up what you already have. So if you just want to add more colors, then yes, you can go ahead and add them on top of what you have now. But the new colors aren't going to intermingle with what's already there. They'll be on top of it.

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Thanks guys, appreciate the input.

You can definitely put another clear coat of epoxy over the first and add more colors to the clear base coat. As Tom pointed out they won’t appear to mingle or blend with the base colors but that can create some cool depth to the marbling. You can also add a little bit of the colors from the first layer of marbling to the colors in the second layer and you’d probably get a pretty nice look.