I thought that 30d stuff was a type of sil. so.what should I make the tarp out of.
type of material ie: polyester, nylon ect....
a number ie: 7d 30d 70d ect.... this describes the construction of the material and the weight oz/sqyd
coating: breathable, no coating at all- dwr, durable water repellent- sil, silicon impregnated- pu, polyurethane coated
what is your style of camping? what do you want out of a tarp? what is most important to you?
nylon: stretches when wet should use tarp tensioners needs a coating
polyester: dose not stretch needs a coating
cuben: very light weight and pricey no coating needed
most of the sil coated nylons seem to be either 1.1 oz or 1.9 oz and this is typically the before weight - before the coating has been applied.
polyester - i'm not so familiar with (i imagine similar to the nylons)
cuben - very light weights down to fractions of an oz no coating needed as it is a bonded material
sil - silicon impregnated, most people have no problem with this at all myself included though there are reports that it may 'mist' if subjected to prolonged and intense rainfall
pu - coating applied to material, think cheap rain suits or dry bags, has a 'rubbery' feeling to it, water proof. in my experience works well but after time quicker if abused will start to peel off
i'm sure that there are points that i have missed and that others will chime in as well......