Thank you to all who participate and voice your opinion. My goal is to create a reference for those of us who have basic questions. I will keep updating this first post as we move forward so if you have a question please ask it. Better yet, if you think there is something not covered and should be, then post it. I will add it and create a link to your post as a reference.
Q: What does the letter D refer, for example 30D?
A: "D" stands for Denier. It's a numbering system for fibers, filaments and yarns, in which the lower numbers are lighter/finer and the higher numbers heavier/coarser. Denier is the mass in grams of 9,000 metres of the yarn. The denier of yarns used to weave mainstream light-weight tent fabrics fall in the 30d to 75d range. It is common to use the yarn denier to describe the fabric, for example, "70d nylon". This simply means that the fabric is woven from 70 denier nylon yarns and, alone, is not a reliable comparison of fabric mass.
Q: What does the letter T refer, for example 190T?
A: "T" stands for Thread Count – specifically the number of warp and fill threads in a square inch. The lower numbers represent a loosely woven fabric and the higher number a tightly woven fabric. These two numbers together help indicate the strength and feel of a piece of fabric.
Q: Is a 30d fabric half the weight of a 60d one in the same type of fibre?
A: The answer is no because it is also a matter of weave density, stated as ‘thread count’ or ‘yarn count’. A 30d yarn will be about 70% the diameter of a 60d yarn or the same fibre (half the cross-sectional area). Fabrics made from finer yarns are naturally more finely-woven, otherwise the fine yarns would be widely spaced and the fabric loose and unstable. Weave density is measured by counting the number of warp yarns or 'ends' there are across one inch of the fabric and adding to this the number of weft yarns or 'picks' there are down one inch of the fabric. 75d 190T taffeta, a common tent weave, has a total of 190 yarns (maybe 90 ends per inch plus 100 picks per inch), and all the yarns or threads are 75 denier. A typical thread count for a stable 30d fabric is 240T. In its ‘loom-state’ (before any finishes are applied) this 30d fabric has a mass per unit area over half that of the 75d fabric but the denier ratio is well under half (at 0.4). After a coating and other finishes are applied the relative difference in finished mass between the two fabrics may be as little as 20%, a far cry from 30d vs 75d. (For your reference, 1 ounce per square yard = 34 grams per square metre).
Q: If I want to make a basic 10’ hammock, which fabric will be the lightest?
A: You will have to figure out the GSM (grams per square meter) but generally speaking when comparing the same denier, ripstop .
Q: How do I do that?
A: 1.Cut a fabric sample of 10cmX10cm, 2.Measure weight of that specimen (sample) in grams. Here you have fabric weight per 100 square-centimeter. 3.Convert fabric weight into grams per square-meter. To calculate it multiply above weight by 100. This will be GSM of the fabric. 4.For accuracy test with multiple (e.g. 5 samples) samples and calculate average GSM.
Q: How do I convert GSM to oz/yd˛ and vice versa?
A: There is an easy way to convert gsm to oz/yd˛. Divide the gsm by 33.906. To determine gsm from oz/yd˛ you do the reverse - multiple by 33.906.
Q: What is Taffeta material?
A: taffeta, cloth, originally silk but now also made of synthetic fibers, supposed to have originated in Persia. The name, derived from Persian, means "twisted woven." Taffeta is in the same class and demand as satin made of silk. The cloth is made of a plain or tabby weave, and the textures vary considerably. For more info see Ramblinrev's post #5 below.
Q: What is Crinkle Fabric? (Crepe)
A: A lightweight fabric of silk, rayon, cotton, wool, man-made, or blended fibers, and characterized by a crinkled surface. This surface is obtained through the use of crepe yarns (yarns that have such a high twist that the yarn kinks), and by chemical treatment with caustic soda, embossing, or weaving (usually with thicker warp yarns and thinner filling yarns). Although crepe is traditionally woven, crepe yarns are now used to produce knit crepes.
Q: I see fabric manufactures listing taffeta and crinkle as parachute nylon. What’s up with that?
A: See post #3 below from Ramblinrev
Q: What is Ripstop Nylon?
A: There are multiple ways to manufacture ripstop nylon. Most of the time, the ripstop grid is actually made by using the same D fiber just woven tighter within the grid structure. This isn't always the case, as you will see some fabrics with a designation such as 300Dx400D, meaning that the base fabric is made from 300D thread while the reinforcement ripstop grid is made with a thicker 400D thread. In such a case, the ripstop grid will be noticeably raised compared to the base fabric.
Q: What is Air Permeability?
A: Air Permeability is the ability of a fabric to allow air to pass through it. While Air Permeable fabrics tend to have relatively high moisture vapor transmission, it is not necessary to be Air Permeable to be breathable.
Q: What is Breathability?
A: Breathability is the ability of a fabric to allow moisture vapor to be transmitted through the material.
Q: What is Calendering?
A: Calendering by definition is a mechanical leveling, and segmenting process for “finishing” fabrics or webs to obtain or produce a special effect. More specifically Calendering it is a process by which the fabric is folded in half and ran through heated, heavy rollers to seal the tiny holes in the weave. The result is a fabric that has two distinct sides, one shiny (the calendered side) and one unaltered or matte finish.
Q: Does calendered mean that it’s downproof?
Q: Does downproof mean that it’s been calendered?
Q: What is Silnylon?
A: There are 2 types. See post 3 below from Ramblinrev for more info. The best is made by impregnating a thin woven nylon fabric with liquid silicone from both sides. This makes it strong for its weight, as the silicone substantially improves the tear strength. It is also highly waterproof, but not breathable.
Q: What are some key characteristics regarding Polyester?
A: Polyester - Absorbs less water than nylon, dries slower, more UV resistant than nylon, resistant to stretching and shrinking, resists pilling, mildew resistant.
Q: What are some of the key characteristics regarding Nylon?
A: Nylon- Absorbs more water than polyester, dries quickly, stretches, shrink resistant, mildew resistant.
Q: Between Polyester and Nylon, which is better for color especially patterns? e.g. Camo
A:Polyester absorbs more color faster than nylon due to the same properties that made it better at wicking water. Dyed polyester expels the water in the dye but not the dye itself, which bonds with the fibers. Nylon absorbs water, resulting in less dye bonding to the fibers. Polyester is hydrophobic, meaning it does not absorb water. This means that when it is dyed, only the color of the dye dissolves into the fabric (not any water-base), making the dye permanent. Nylon possesses hydrophilic qualities (that is, it absorbs water). Its inability to repel water causes the fabric to swell and ultimately weakens the molecular structure. The dyestuffs used on nylon tend to oxidize, a reaction which is catalyzed by light. The microscopic effects range from color fading to complete degradation of the polymer matrix.