Need Help!- Engraving pine leaves 'ridges' where grain is

[BlueRebel]

I finally got my new laser engraver last week. Its a Redsail M900. Happy with it so far but I'm having an issue when I'm engraving into wood. The pine that I'm engraving has raised ridges where the grain of the wood is.
I presume the grain is harder than the rest of the wood so the laser doesn't burn as deep.
Does anybody know how I might get around this problem with some changes to settings or maybe the wood type.
Any help would be appreciated.
Thanks

[awerby]

All softwoods have soft grain that grows in the summer and hard grain that grows in the winter. It's not surprising that the laser cuts them differently. Try a hardwood like maple, for example, which has more even grain.

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

[txcncman]

Wood has different densities throughout. Different densities will burn away differently.

[BlueRebel]

Thanks for the responses guys. I will try some different types of wood. I wanted to work with pine as its soft and seems quite easy to work with, but I guess that has its disadvantage too by the sound of it. I'll try some maple as you suggested.
Thought there might be some setting that might help the problem though, like doing two passes maybe?