If the material in a vessel increases in density what would a float indicator read?

You are assuming that the material is a liquid. That is important and should be stated.

Now consider the definition of 'float'. All the fluid above the top of a body pushes down, and everything below that point pushes up with an equal force. The same is true at the bottom of the body, but the forces are greater there, so if the sum of all those forces is equal to or greater than the weight of the body, the body floats. If less than the weight of the body, the body sinks. Obviously a denser fluid makes more pressure on a body so it floats higher than it would in a lower density fluid.

If you swim in the Great Salt Lake or the Dead Sea or any very salty water, your body will float much higher than it does in pure water. So much higher that it is difficult to keep your face out of the water, because your body tends to float with arms and legs hanging down.