This is a question we get asked often. Understanding how a poly-fill lining works in a horse rug can go a long way to ensure your horse's rug is actually doing them benefit in the cooler months.
What is polyfill in a horse rug like?
Polyfill is very similar to the poly fibre that you get inside a pillow (much like hobby fill) Polyfill used in horse rugs comes in long flat lengths of a roll.
The lining works much like your roofing insulation it traps heat in the air pockets in the polyfill lining and slows down the radiant heat out of the rug and away from the horse. We use either 200gram and 300grams of polyfill in our Alpine range of winter horse rugs. So a rug advertised with 300grams of polyfill means for every square meter of laid out polyfill lining - it will weigh 300grams. Please click on the attached link for our Lined Winter Turnout Range.
A good analogy is to think of a cotton ball you may have in your medicine cabinet. When you take it out of the packet - it is relatively compact. (i.e. actually quite close to what 300grams of polyfill is like inside a horse rug.) It would have good insulation properties as there are lots of tight air spaces to act as insulators in the body of the cotton ball. If you then start pulling it apart and spreading it to make it thinner, you start losing those insulated air pockets as the cotton ball opens up and thins out.
We have done lots of testing with different grades of polyfill and insulation effects. Some manufacturers offer horse rugs with 100 to 150gram grams of polyfill. This is more for marketing than actual benefit. The rug generates its warmth by capturing the air pockets in the polyfill lining. When you drop below 200grams grams of polyfill, it will have a limited insulation effect, as there just isn't enough body in the filling to trap air and create an insulation layer. It is not until you get near 200grams of polyfill in your horse rug that you get enough body in the polyfill to start making a real difference.
If you pulled open a horse rug with 100gram of polyfill, you would be very surprised how thin the polyfill lining is spread.
Comparison of polyfill lining 300grams vs 200grams
There is also a huge variation in the quality of polyfill. The majority of polyfill used in horse rugs is produced in India which is inferior in all aspects compared to Chinese produced polyfill. (At Caribu we only use Chinese Polyfill). i.e. a 300gram polyfill from India can often only be as effective as a 200gram polyfill from China. The weight of the polyfill is the same - but its the technology used to create the open weave that varies and its ability to ''bounce back' and not flatten out. There is also different grades of polyfill within each weight to complicate matters more!
The actual insulation performance between a good 200gr vs. a 300gram isn't as dramatic as most people like to think. It does come down to personal choice and your horse, as to how much polyfill you should opt for in your horse rugs. It also depends on how long your horse's coat is - or how short you wish to keep it. Also depends how early or late in the season you start and stop rugging. Some horses are 'hotter' than others and some feel the cold more (young and older horses especially)
Many people find 200grams isn't enough in the middle of winter and they need to use multiple under rugs to get the desired level of insulation. Others prefer to use 300gsm and only layer a lighter rug underneath (or use no under rugs at all). it's much quicker to use one 300gr rug than a 200gr and multiple under rugs. That's a lot of buckles, surcingles and leg straps to do up/undo every day!
Medium Fill (200grams of Poly Fill) (Our Alpine-Mid Range), ideal for areas that experience warmer Australian Winters. You will see some manufacturers also make them a 100-150gram version. This is more for marketing than actual benefit. The rug generates its warmth by capturing the air pockets in the polyfill lining. 150grams and below of Polyfill has very little insulation effect and it's not until you get to 200grams+ that you get enough body in the polyfill to make a difference. Polyfill linings do compress over time and provide less insulation as they thin out, this is an important factor to consider when choosing between a 200gr and a 300gr. A 200gr will give you a little more versatility to start rugging a little earlier in the season.
Heavy Fill (300grams of Poly Fill) (Our Alpine Heavy Range), ideal for Australian Winters. 300grams is the most popular filling for winter turnouts, they offer good warmth and often don't require any under rugs. We recommend these over a 200gram rug, 300grams will experience less compression over the life of the rug and continue to provide the best insulation performance.
Polar Fleece Lining. Our polar fleece lined combos bridge the gap between an unlined turnout and a 200gram polyfill turnout. Using less than 200gr of polyfill isn't effective, polar fleece performs well at both providing some added insulation and also helping to wick away moisture that can build up quickly under an unlined rainsheet. (for ease of comparison - think of a polar fleece lined rug as performing the same as a 100gram lined combo)
How can a 300gr winter rug be just as good for a Queensland horse as it can one for one in the southern states? We all get an acclimatized for our environment. In Winter in Queensland people start saying its cold when the nights start dropping down to 15C! because we are used to warmer weather. So on go the jumpers, because we feel the cold - same goes for the horses. At the same time, those in the southern states don't feel the same cold effects until the night temps get much lower.
Rarely is a winter rug on its own all your horse needs. Most people tend to use under rugs (underneath a winter polyfill rug) to build up the desired level of warmth needed. Depending on your climate and condition of your horse, this may be just one under the rug, or a combination a few different under rugs.
What if 200gr is to warm for my horse? Finding a balance for keeping your horse warm in cooler weather is an ongoing process and depends on why you are rugging your horse. Certainly, in some climates, 200gr may still be too warm. Our advice in this situation is that you are better to use an unlined turnout rain sheet and use in conjunction with an under rug/s to find the desired insulation level.
Do you get confused when comparing ‘gsm’ to ‘grams’ & ‘deniers’ when looking at the specifications of horse rugs? Well, you are not alone! Read our helpful article here.