What do the common letter parameters T, D, G, PVC, PU and PA mean for umbrellas?

What does T stand for in fabric 190T?
T stands for density (the sum of the warp and weft densities in 1 square inch).
To measure this, measure the warp density + weft density with a density mirror and multiply by 2.54 to equal the T number.

170T is the worst specification, 190T is almost as bad

What does the D in 300D stand for in a large umbrella?
D is for Denier, which means the thickness of the thread (the amount of grams in a 9000m length of fibre at a nominal moisture return rate)
What is the essential difference between T and D?
T is for density and D is for thread thickness.
Generally T is used for polyester spinning and D for oxford spinning.
2、Sometimes 300D polyester fabric is expressed in g. How is the conversion between D and G?
G, generally speaking how many how many grams per square metre g/m2, insiders will omit per square metre, directly how many how many grams.
There is no conversion between D and G.
Is 300D polyester fabric weighing 180G that means 180G of polyester fabric is 300D?
A 300D polyester fabric is not called a polyester taffeta, it is called an Oxford fabric. 180G means that it weighs 180G per square metre.
You cannot say that a 180G polyester fabric is 300D because the grammage changes during dyeing and other finishing processes.
3、It's ounces, right? 1oz = 31.1035g. No need to actively calculate according to this formula
4、UV resistance has a special glue, generally light colours are more difficult to do, dark colours are easier to meet the standard.
If 100% resistance, it does not seem to work.
5、 more contact will be able to distinguish, no contact I said it is useless, PVC is better to distinguish, there will be a thicker film.
PA coated with white and PU coated with white or coated with PA and PU transparent glue from the appearance is very difficult to distinguish, but PA and PU still have a difference, one is the feel: PA feel more astringent PU more smooth, PU elasticity than PA good; a gloss: PA no luster, PU luster brighter, and a PU has a good sense of film, touch the feeling of leather film. In short, PU is brighter, good elasticity and has a film feel, while PA does not have these conditions.

Of course, just rely on these general novice or difficult to distinguish, right, to teach you a tip: 1、 with a rubber pressed hard on the surface of the cloth and then lift, PA will follow the rubber sticky up and PU is not sticky. 

2、in the 2 cloth coating surface of each a few drops of toluene (such as conditions), and then gently rub with your hands (pay attention to protection, hands do not directly touch the toluene), PA coating will fall, PU will not fall off