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Thermal Fabrics to Keep Hot Hot and Cold Cold
Years ago the Thermos® company had the slogan, “Keeps hot things hot and cold things cold.” You can’t say it much better than that. Did you know there are fabrics that help you do the same thing? These aren’t the heavy industrial materials that keep steelworkers, astronauts, and firefighters safe, but honest-to-goodness fabrics you can actually sew with.
Thermal fabrics are useful for all kinds of projects where you want to keep hot stuff hot and cold stuff cold, such as pot holders and oven mitts, table pads, lunch carriers, shopping totes, ironing board pads, outdoor stadium cushions, tea cozies, and many other items.
And, because of the metallic coatings common to many of types, and the fact that they’re easy to sew, you can even use them to make some pretty creative costumes – from medieval armor to Lady Gaga!
The options fall into three basic categories:
- Thermal Batting, which has insulating properties.
- Thermal Fabric, which can withstand high temperatures without scorching.
- Thermal Interfacing, which is a lighter weight insulating option.
An important note about microwaving: The materials listed below that have a metallic layer specifically say, “Do not microwave.” None of the rest actually state they are safe to microwave either. So for any kind of thermal fabric, unless it specifically says it’s microwavable, we recommend you don’t risk it. One exception, described at the end of this page, is Wrap-N-Zap by Pellon, which is specifically designed to be microwaved.
The thermal batting product that’s been around the longest is Insul-Bright from The Warm Company. It’s made with hollow, polyester fibers that have been needle-punched through a non-woven substrate, and then through a reflective metalized poly film. The needled material is breathable. The hollow fibers insulate by resisting conduction. And the metalized poly film resists radiant energy by reflecting it back to its source.
It contains no resins or glues and will not shift, migrate, or bend. You could use it in clothing, but it would be rather noisy. However, babies and animals often love the noise and like to scrunch it up in soft books and toys.
Insul-Bright is machine washable, easy to cut to size, and apart from being just a bit slippery, is quite nice to work with. Most sources offer it by the yard in 22″ and 45″ widths, and a few outlets offer 36″ x 45″ pre-cuts.
Even though we’ve listed this material in the ‘batting’ category, The Warm Company does suggest considering two layers or layering Insul-Bright with a standard cotton batting if you are using it for a high-heat application.
A number of sources offer Insul-Bright online, including Fabric.com. It’s also readily available at many local fabric and craft stores.
This space-age thermal batting from The Warm Company was originally designed for insulating air conditioning ducts or wrapping your hot water heater (for which it’s very effective). But Insul-Shine is actually quite sewable.
You can make something simple, like a reflective visor for your car or to put in your RV windows to prevent sun damage. If you’re looking for a mod metallic look, you could also use it to cover a headboard, throw pillows, or make a budding astronaut very happy with some rocket wall art.
Insul-Shine has two layers, reflective material and insulating polyester batting. The metal surface wipes clean and actually acts as a water barrier for soft coolers, diaper bags, and bottle carriers.
It is washable, but doing this may dull the reflective side. Sold in 22″ and 45″ widths.
You can find it at Amazon and Fabric.com among others.
Solarize, a thermal product by Fairfield, is a uniquely thin metallic insulating fabric. Less noisy and crinkly than other offerings, Solarize still creates a strong thermal barrier that keeps things hot or cold. And it works with the shiny side in or out – you choose. Keep the shiny side exposed to help conduct heat or reflect light.
It is a sew-in product, made of 50% polyester + 50% aluminum, and the standard width is 22”. You can purchase it as yardage or get it in a “grab-and-go” pre-cut package of 22” x ¾ yd.
Use Solarize inside pillows, fabric scarves, mittens, jackets, hats, and blankets for added warmth. Add it to casserole carriers, potholders, and trivets. Cool things down by Solarizing inside can cozies, thermal freezer bags, or ice pack wraps.
You can purchase Solarize directly from Fairfield or find it Walmart and other retailers. You can also buy full bolts from Amazon.
Iron Quick is a specialty fabric made of 100% aluminum with 100% cotton backing. It’s designed to protect from heat (up to 399˚), but does not have any insulating properties so it’s long been the go-to choice for things like ironing board covers.
When you need insulating as well as heat protection, like in your oven mitts, Iron Quick also comes as a quilted material. This is simply the regular Iron Quick fabric with a 100% cotton backing, plus polyester batting and a polyester/cotton backing. This doesn’t afford a huge amount of insulation, but you could use more than one layer or add a layer of regular or thermal batting.
Both varieties come in the same 45″ width. When sewing, you should use a size 80/12 needle.
Neither Iron Quick products should ever be used in the microwave.
Both can be machine washed but should then be air dried – not tossed in the dryer. You can also use a damp cloth to wipe clean.
We found it a bit hard to source online. Retail outlets may be able to help you order it. Nancy’s Notions does carry the non-quilted Iron Quick products by the bolt.
Therma Flec is a lightweight, heat resistant cloth similar to the Iron Quick but made from 80% cotton/20% polyester. It is scorch-proof to 360˚, but like the Iron Quick cloth, does not provide insulation. However, also like the Iron Quick, you can find Therma Flec in a quilted version for items such as hot pads, oven mitts or ironing board pads.
Both the flat cloth and the quilted option are available in two colors: silver and light gold, all in a 43-44″ width. Don’t put this product in the microwave.
We found Therma Flec in silver to be more readily available, finishing it at Amazon and Vogue Fabrics.
Back in the 1980s, the 3M Company introduced an amazing new insulating material called Thinsulate. Ounce for ounce it had one and a half times the warmth of down and twice the warmth of other high-loft insulation materials. It meant you could get sleek ski gloves that were just as warm as giant, puffy mittens.
A quarter century later, Thinsulate is still amazing. Made from microfibers that are only a tenth the size of of other synthetic insulation, it’s much more effective at reflecting back heat. And Thinsulate absorbs less than 1% of its weight in water, allowing it to retain its insulating ability even in damp conditions. You can use it in any kind of project where you want to keep warm but don’t want a lot of bulk, such as jackets and blankets.
You can get varying densities of Thinsulate, depending on the weight and R-value (insulating property) you want, from 1.6 up to 2.9.
Thinsulate is machine washable and dry cleanable once you have sewn it inside your project. It is a bit tough to find as yardage, but we did locate Thinsulate online at Vogue Fabric Store and The Rain Shed. It’s available by the yard, 60″ wide.
Pellon makes a 100% polyester interfacing called Thermolam, which is a needle-punched fleece with a protective scrim that can provide some warmth. It’s available by the yard at a 45″ width as both a sew-in or a fusible and is machine washable. It’s considered a heavy-weight in the general world of interfacing, however, it doesn’t have any loft, so it isn’t a choice for projects that call for high-level insulating and/or padded properties.
There’s no microwave warning for this fabric, but then again, we couldn’t find anything that said it was okay to use either. Maybe you should just forget the microwave, huh?
Fabric.com offers a good selection on Thermolam (both sew-in and fusible).
Wrap-N-Zap by Pellon is the only thermal product mentioned on this page that we can safely declare to be microwave safe. It’s got Zap in its name and it says “Microwave Friendly!” right on the package.
Made from 100% cotton batting, without glues or other chemicals that could leach into foods, Wrap-N-Zap is designed for projects like insulated baked potato bags and casserole warmers – situations where you heat up the food inside the cover and leave the cover on to keep food warm.
You can machine wash Wrap-N-Zap after you’ve sewn it into a project, but you should only use cotton fabrics, threads, and trims to insure it retains its full microwave-safe designation.
We found it at Fabric.com as a 45″ x 1 yard package and at 22″ wide on a 10 yard bolt.
Thermal fabrics are a “hot” trend
When we first researched this topic several years ago, we could only find about four kinds of thermal fabric or batting that was sewable and relatively easy to locate as yardage. Now we’re finding a lot more options. And we didn’t even include all the new energy-saving materials you can sew into things like super thermal window shades. It’s nice to see the selection growing.
Be adventurous and try some projects that are made to keep hot things hot, and cold things cold. Below are a few Sew4Home projects to get you started:
And, of course, all kinds of hot pads and oven mitts.
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I would like to make an insulated sleeve for my portable air conditioner exhaust hose, to be closed with velcro length-wise. The sleeves sold on Amazon are designed for 5-6″ diameter hoses (round), while my dual hose exhaust opening is a 7″x12″ oval/rectangular shape. The hose extends approximately 42 inches to the window (Danby dual hose exhaust air conditioner). What insulated fabric would you recommend for a simple solution, for someone who is not familiar with sewing but is attempting this DIY project (ie fabric that is easy to work with)?
Hi there – I’m afraid I’m always reluctant to give recommendations for HVAC questions like this as we have ZERO experience in that area. Our knowledge of thermal products is based on sweet little things like oven mitts and insulated water bottle carriers 🙂 All I can really say is that the Insul-Shine product listed above does appear to been designed for insulating air conditioning ducts or wrapping your hot water heater. A home improvement store would likely be your best source for the proper material.
Hi, we sell blueberries at farmers markets and am wanting to make covers to go over a stack of crates full of cold blueberries in punnets to maintain their coldness from the coolroom for the morning until any leftovers can be put back into cold store. What fabric would you recommend?
Hi Rachael – We’ve not worked with anything like that, so in many ways, my guess is probably as good as yours 🙂 In general, I’d maybe consider a double layer of Insul-Bright perhaps sandwiched between a rip stop nylon that could sit on the blueberry side and a reflective material, like the Solarize or even a lightweight space blanket for the outer layer. That said, maybe try this thought – or your own great idea – on a small flat and see how it works for you before investing in yards of anything.
I have been developing a “cooling system” that uses batteries for mobile applications. I have been thinking about a larger scale run for farmers
Feel free to reach out with any questions
Thanks for this. What would you suggest for a cover for the front of a window air conditioning unit? The goal is to keep cold air from blowing in through the vents in the winter. (Something not ugly would be a bonus!)
Hi Christina – we’ve never done a project like that, but I bet there are others online who’ve done it. Have you tried a quick Google search? I tried searching with “how to make a cover for a window air conditioner” and found YouTube videos, static project articles, as well as quilted wraps you can buy.
I love ironing small quilting pieces on a thick felt pad. Problem is that the steam goes through the felt pad and damages the finish on the wood surface below. I’d thinking of sew an underpad to protect the table. I’m thinking of two sheets of cotton batting with a layer of Insul-shine in between. What’s your opinion?
Sounds like it could work. You also might be able to find a table pad at a thrift store to help protect the table. The only caution I’ve heard on a regular basis is regarding the reflective ironing board covers: “Avoid the Teflon® coated, heat-reflective ironing board covers. This type of coating reflects heat and steam, preventing them from passing through your fabric, which kind of defeats the act of pressing!” So – you do want the steam to be able to pass through – just not reach your table.
I need to make curtains of some sort that will keep out the heat in summer and cold for winter. We have turned an old school bus into a tiny home.
Take a look at the Warm Windows options from The Warm Company — the same folks who make several of the products described above: https://warmcompany.com/?portfolio=warm-window%e2%93%a1
I am making a circular insulator pillow for freeze dryer. The pillow is made of outside fabric and fleece (1 outdoor layer-2 fleece-buffalo stuffing plus fleece scraps-2 fleece-.1 layer outdoor fabric) . Would this be enough for temp as low as -40 or should I add a layer of insulbrite.
Hi there — That’s a pretty specific use for which we don’t have any direct experience, so I can’t really give you any technical advice. Perhaps reaching out to some of your other Freeze Drying Pals would be helpful. In general, I could say that I don’t think adding a layer of the Insul-Bright would hurt anything.
I’m going to make a tortilla Warmer. We don’t like to warm or reward our torts in he microwave. I have some insulbrite. Should I use batting also? On both top and bottom sides. Batting insulbrite batting sandwich and of course the two inner and outer fabrics.. I’ve made them w/o the insulbrite, but my tortillas don’t stay warm.
Hi SewMelissa – As mentioned above Insul-Bright contains metallic fibers. It really isn’t suitable for the microwave.
IF I MAY…
Insul-brite won’t maintain the warmth like expanded Styrofoam does (little white beads). Foam is better for cleanliness where you can wipe the foam surface, not so with Insul-brite. Also the foam can be painted or fabric glued onto it.
HOPE THIS HELPS
I am crocheting a pattern that asks for heat proof fabric. What do you recommend?
Hi Liz – what are you making? And, do they actually use the term “fabric” rather than “thermal batting”?
Okay I know this is going to sound a little out there and ridiculous but I’m building my son a rocket ship type clubhouse on our land and was wondering if I layered this all on the outside of the body of the rocket if it would keep the summer heat from roasting all the kids inside standing around 35 ft tall and about 12 and 1/2 ft wide
Or would you not recommend using this for that type of use and if not do you recommend anything?
Hi there, Shane – this type of project is WAY out of our area of expertise. Creating a heat-safe hot pad is miles away from making a cool rocket ship clubhouse. Some of the products listed above can be used for insulating water heaters and pipes and such, but that is really more about keeping heat in. For more a reflective property to try to keep things cool, you would probably be better off reaching out to companies that handle more commercial kinds of insulation. A spray foam or foam board might be better, but really … we just don’t… Read more »
I would recommend using mylar on the outside and then using a spray foam insulation on the inside. I feel like that would be the easiest, cheapest and best end-result.
You would better off use RV roof reflective paint, comes in colors and more cost effective.
It’s insulating and waterproof & can be repainted anytime keeping it looking new.
Hi I am looking at sewing a pellet grill blanket. To keep the heat in the pellet grill ( reflect it back to it), so it stays warmer, and more even tempurature with use during winter months. I was planning on using cordura( water and wind resistant) as the outside layer, but am unsure what to use next to the pellet grill to reflect the heat back to it. The grill is often at temps of 225 degrees Farenheit. Does anyone have any suggestions? I have sewn a smoker blanket previously using a fibreglass welding blanket in the past. Not… Read more »
Hi Leanne – We don’t usually work with situations where you need to protect items that sit at such a consistently high temperature. In general, the Insul-Shine product described above might be one of the better options since it can be used on duct work. You might want to reach out directly to the experts at The Warm Company: https://warmcompany.com/product/insul-shine-22-x-30-yard-bolt/
I used the metallic side towards the body for both a parka and ski pants, in combination with wind proof material for winter wear. Northern Manitoba where the temperature can be severe! Very light, flexible, washable, and above all warm!
Thank you for weighing in with your suggestions from the chilly North!!
hi- I’m working on a design for homeless folks out in cold weather-a shirt or similar-my question as far as radiant heat from the body being reflected back, does the aluminized fabric need to be against the skin? thanks
Hi Pat – Our reviews were based mainly on uses for smaller sewn items for the home, so we really don’t have any expertise to share for cold weather wearables. You might be better served looking for specialty fabric that is designed specifically for the outdoors. We often turn to The Rain Shed, an online company of active lifestyle elements: https://www.therainshed.com/shop/Fabrics/UNIQUE-FABRICS.htm
Hi, I am looking for a fabric that will conduct heat to the anesthesized kitties in my care and not burn them. I have warm water bottles heated up in microwave then covered in a layer of fabric to put next to their recovering from anesthesia bodies. I am always afraid of thermal burns. What fabric would you suggest to conduct heat safely to their little bodies that often get cold during anesthesia?
Hello Heidy – I don’t think the fabrics described above would be the best for your situation. Instead, wool or fleece would likely be the best and the softest. With kittens, fleece might be better because there are less issues with allergies. Some fleece is thicker and denser — look for that and get one with a soft plain solid color. Could also double up the fleece.
Could I repurpose an insulated grocery bag into a self-warming cat mat?
Hi Suzie – We haven’t created anything like that so we can’t give you a guaranteed response based on hands-on experience. In general, cats can turn just about any layers of bedding warm 🙂 just from their body temperature. I can’t think of a reason why re-purposing an insulated bag would be a problem. Just wrap it in other soft and cozy layers. A benefit of the bag is that is might be a little “crunchy sounded” – a noise that many kitties like.
I want to make a coffee cozie. Which product would be the best and easiest too sew with? Keep hot coffee hot and iced coffee cold.
Hi Sandi – for our own coffee cozie projects, we’ve used a layer of the Insul-Bright.
What should I use to put in a quilt or blanket that will be used to keep warm while watching a football game on Cleveland Ohio in the winter
Hi Toni – I don’t have ONE perfect answer, it depends quite a bit on what the exterior layers of your blanket are/will be made of. Several of the metallic products listed here can be “crinkly” – something you might not like in a blanket. If that’s the case, one of the thermal fabrics would be better. In addition, a layer of good ol’ wool could be great if getting wet is not an issue. Finally – you could even get one of those off-the-shelf space blankets, which tend to be quite thin, and layer that in quilt batting, thermal… Read more »
hey, fyi, I tried that…the space blanket option. I tried to sew it into a piece of clothing to retain heat, but its too fragile, it tore immediately along the seam line 🙁 my experience anyway.
Thanks for weighing in with your experience. Those blankets are pretty thin!
I’m looking for a fabric I can put in a freezer that will keep bottles cold. Any recommendations?
Hi Shanice – I’m a little confused because if the bottles are going into a freezer, won’t the freezer itself do the job of keeping the bottles cold? Are you wanting something to put in a carrier, like an ice chest? If os, one or two layers of the Insul-Bright would work well for insulating. For the exterior fabric, you want a waterproof fabric – like an Outdoor fabric or waterproof canvas, or a sport vinyl of some sort. We have a local company here in the PNW that specializes in outdoor fabric, hardware, and kits. They might have some… Read more »
Hi Liz: I believe she’s doing what I already did. Making a freeze-cozy to go around different shape bottles. The medical gel ice packs used for injuries are in pliable plastic baggies. I removed about 1/3 the contents then resealed the small hole with hot-melt glue. It then will conform around a shape wrapping it with string. Not to tight. don’t want thin spots. When I place the wrapped bottle in our travel cooler, I wrap a wrinkled up plastic grocery bag around it leaving the top open to uncover-remove-replace-recover quickly. Seems redundant but the drink stays cold all day… Read more »
Thanks for the excellent detail.
Looking for a fabric that I can sew a cover for our camper van to stop condensation on the windscreen at night ….. any suggestions please….preferably able to be put on outside.
Hi Jean – That is a pretty specialized project that we’ve not attempted before so I really don’t have a knowledgeable suggestion for you. In general, I think you’d want a waterproof fabric – something specifically for outdoor projects. We have a local company here in the PNW that specializes in outdoor fabric, hardware, and kits. They might have some really good options to review. If you can use their stuff to make tents and jackets and sleeping bags, you could certainly fashion a windshield cover. https://www.therainshed.com/
What would you use to make a flat iron case? What should it be on the outside and some sort of thermal interior so you could put the iron in it when it’s still warm.
Hi Share – The Insul-Bright would be our choice for that type of project. I’ve linked below to our flat iron case. For it, we used quilting cotton for the exterior and cotton twill for the interior. You could also consider a wool for the interior.
Hi great article. We are trying to make cooler bags to use in our cars and take with us to the kiddos sports things. Which of the fabrics would be the best to keep food cool or cold?
Hi Deb – thank you; we’re glad you found us. We tend to go with one or two layers of Insul-Bright between the exterior and lining fabrics of good totes. Here’s one on of our tote examples: https://sew4home.com/zippered-picnic-tote-with-lots-o-pockets-inside-out/
This is a great article. I’m looking for the best fabric that would take on heat if it was heated and retain if for a while. Which of these do you think would do that best? Thank you!
Hi Laurel – I’m not sure how you plan on heating your item nor what it is – but if you are thinking about microwave heating, remember that many of the options above have some metallic content so they are right for the microwave. The “Wrap-n-Zap” is the only one that is actually designed for microwave heating. It’s what we used for our Tortilla Warmer – if you are thinking about something like a blanket that you could warm in the dryer, you’re options are broader, although the thermal fabrics and interfacings would probably be better because they aren’t are… Read more »
I am wanting to sew a denim apron with a heat reflective material on the back side to keep a chef cooler and safer. Any advice on what to use? Thanks!
Hi Anastasia – We haven’t really experimented with any of these in terms of keeping a person cool. The only suggestion I could mention is that the thermal fabrics are likely the only ones that would have any comfort level as a lining for your denim apron. They would world help with protection, but I’m not sure what level of “cooling” property they would have.
I want to make a curtain out of quilted reflective thermal material for my RV 150″ W x 84″L. Any suggestions on what material I could use that isn’t so expensive?
I am looking for a Quilted high heat (Approx 500degrees) resistance waterproof or water resistant (Even something that can be just wiped down) fabric. Looking for possibility to have different colors or patterns. Also, that is sewable.
Hi Kris, That is quite a tall order of specifications. I’m afraid I cannot think of anything that meets of of them. You probably need to search/reach out to specialty fabric manufacturers who deal in the commercial production fields.
Hello, I was wondering if you could help me with an enquiry. I would like to know if the thermal fabrics have a sort of grading, of how many hours it can retain heat for. I am asking with regards to food, specifically flat bread etc. I understand that tortilla warmers offer around an hour or so of heat retention, but I am looking for how to layer the best fabrics, so that the flat breads are hot, but not soggy or wet. I usually just use a tea towel, which I place the freshly made flatbed, and roll it… Read more »
Hi N.U – I’m afraid I don’t know if there is any accurate chart for that kind of thing. The problem is there can be so many variables: the number of layers of thermal fabrics, the type and thickness of the outer fabric, whether simply keeping warm or heating in a microwave. Our go-to for warmers made with quilting cotton is traditionally a single layer of cotton batting (for microwave uses) or a single layer of InsulBright for things like hot pads. Below is a link to our Tortilla/Flat Bread warmer, which might also contain some ideas for you: