Create a square selection of 8 pixels.

Image>Map>Invert (Cmd-I)

Press (Opt-Cmd-Down) twice.
Press (Opt-Cmd-Right) twice
This sets the grid thickness (2 pixels x 2 pixels)

Edit>Define Pattern

Select>None (Cmd-D)

Edit>Fill: Pattern, 100%, Normal.

Filter>Blur>Blur More

Filter>Stylize>Diffuse:Darken only

Image>Map>Invert (Cmd-I)

Apply filter again (Cmd-F)

Image>Map>Invert (Cmd-I)

Image>Map>Equalize (Cmd-E)

Select>All (Cmd-A)

Edit>Copy (Cmd-C) Edit>Paste (Cmd-V)

Image>Map>Invert (Cmd-I)

Press down-arrow twice, press right-arrow twice

Set the Floating Selection layer's mode to Multiply

Select>None (Cmd-D)

Image>Map>Equalize (Cmd-E)

Image>adjust>Hue/Saturation:check Colorize;
Hue=30; Saturation=50; Lightness=-10

Burlap!