We first need to differentiate between High Frequency and low frequency EMF.
In high frequency most electric conductive material will reflect the EMF electric field.
Most Water containing bodies (like trees, earth, human body) will absorb EMF electric field.
as the frequency goes higher the effect is higher.
As the frequency goes lower the effect is less and less.
Creating clothes from High frequency EMF (RF) reflecting materials is possible, but the effect will never be 100%, even if the fabric it self allow close to 100% blocking effect. This is because some of the ELF will make it's way from the opening in the clothes or hats.
In low frequency some special metal material can reflect the ELF magnetic field in 90 degrees. These are usually used in cases of ELF magnetic field emission from electric cabinets.
A full Faraday cage is usually impossible to create.
please see my info site for more info - http://www.norad4u.com/emr-protection RF - http://www.norad4u.com/emr-protection/rf-protection ELF - http://www.norad4u.com/emr-protection/elf-protection