Sinuous spring couch Sinuous springs may be more difficult to repair because they are stiff. Read on. The difference is in both the physical properties of the webbing and the method of installation. Noise: Sofa springs can creak or squeak over time Hello all, I was just wondering if there is a real or percieved quality difference between sofas with sinuous spring and one with coil springs. Danca Furniture a ByMauto LLC company. Cannot find another one. This sofa is upholstered in a beige polyester fabric with a textured In terms of comfort, sofa springs excel at offering excellent support and bounce. House2Home 27" Couch Spring Repair Kit to Fix Sofa Support for Sagging Cushions - Includes 4pk of Springs, Upholstery Spring Clips, Seat Spring Stay Wire, Screws, and Installation Instructions When you buy a Flexsteel sofa, ask about their unique spring systems. It’s the mark of a high quality piece of furniture (except for when it’s fake eight-way han One of the most common seating systems used in modern upholstery is sinuous springs, also known as sinuous wire or zig-zag spring. The most important component being the sofa’s spring system. These springs are constructed from tempered wire and are available in flat or rolled form. Attaches between the clip and the spring. They give continuous support down the length of the sofa and are widely employed in modern furniture design because they are cheap and easy to produce. Feature: We are committed to provide perfect products and services for you. smart frames You generally buy the springs needed in 10-foot sections, and cut them with wire cutters. seating systems are supported by 8 gauge sinuous springs set apart at an ideal spacing to ensure a relaxing and enjoyable seating experience. Zig Zag Springs, unlike tension springs are fixed front to back and up and down. With this system, a series of coil springs are hand-tied into a Make fantastic furniture, seats and ottomans easier with zig zag springs, sinuous springs and no-sag spring. What does this type of suspension look like? Pieces of metal, spaced a few inches apart, zig-zagging perpendicular to the front of the sofa. Although this method is the priciest in comparison to S-Spring (Sinuous Springs), but don't rule out the S-Spring just yet. This sofa is upholstered in a beige polyester fabric with a textured crosshatch pattern, and features rounded arms, three removable back and seat cushions, curved solid wood feet, and gold-tone nailhead trim. Drop-in coil springs . We actually use Sinuous Springs in smaller products such as custom Sinuous springs or serpentine springs get their name because of their “S” shape that resembles a snake’s body. (Has someone been jumping on your couch?) Your first step is to get access to the underside of the couch. They are manufactured with a high-carbon steel and the D Arc option is particularly popular for upholstery projects. These springs are made of heavy-gauge metal wires that are formed into a zigzag pattern The two most popular spring systems for upholstered furniture are 8-way hand tied springs and sinuous springs. Sinuous spring suspension. The springs Perhaps, the most popular kind of furniture springs are sinuous springs. They’re common in modern couches. Sinuous springs are arguably the most common type of sofa suspension on the market. These springs offer good support and create a firm seating experience. The flexolator grid is a suspension that is less common than coil springs and sinuous springs. These are predominantly FIX SAGGING CUSHIONS - Our couch spring replacement kit includes all the parts you need to reupholster a new chair, sofa or fix that sagging couch support. sinuous springs. Tel: 828-328-2201. Upholstery Zig Zag No Sag Furniture Spring (Sinuous Wire) - 8 Gauge/ 10 Yd (30') Roll . You’ll probably come across the term sinuous One of the best coil springs on the market today is the 8-way hand-tied coil spring. COMPLETE KIT - Whether you are working on a new upholstery project or just looking to fix a seat on an antique sofa or chair, this sinuous spring repair kit includes all the parts you need. Feel the seating platform for springs by lifting up the couch cushions and running your hand along the couch. Sinuous Wire. Find out which sofa type suits your style, comfort needs, and interior aesthetics best. It would be perfect in an apartment or small living room. Sinuous springs can last just as long or longer than 8 way hand tied. FIX SAGGING CUSHIONS - Our couch spring replacement kit includes all the parts you need to reupholster a new chair, sofa or fix that sagging couch support. + 32ft Upholstery Stay Wire for Sofa Furniture Springs, 9 Gauge with 40 Clips (32ft Wire +80 Clips) When comparing sinuous springs to other sofa support systems, here’s how they stack up: Sinuous Springs vs. Sinuous springs for seats and No-Sag® spring ends available; Manufactured in %PDF-1. Add a minimalist look to your living room with the Sonny sofa. Lower quality furniture is more likely to use engineered Osborne 268 - Lever Spring Stretcher - Sinuous Wire Springs - Upholstery DIY Tool - Made in The USA. 5 out of 5 stars. It’s made with an engineered wood frame with sinuous spring construction and foam cushions. They are called zig-zag springs because the single band of metal goes back and forth like a quick sine wave. Over 50 years combined experience in upholstery supplies, repair and furniture restoration. Sinuous springs. Best Oversize Sofa. Spring Clips. Have A Question Call (800)-737-7702. Price: $14. The springs are supported by webbing on the underside of the sofa, and the top springs are secured by twine (which is where the name comes in)! Understanding the type of springs in your couch can help you decide the best repair method: 1. Prop65 Warning Accent pillows included, Platform foundation system resists sagging 3x better than spring system after 20,000 testing cycles by providing more even support, Attached backs and loose seat cushions, Smooth platform foundation maintains tight, wrinkle-free look without dips or sags that can occur over time with sinuous spring foundations, High-resiliency foam cushion wrapped in Bring classic design to your living room with this Bridgewater-style sofa. 8 density foam will usually remain comfortable for 10+ years. $26. This recessed-arm sofa is made in the USA with a solid and engineered wood frame and sits on four tapered, solid wood legs. Upholstery springs for furniture are either coiled or produced in a zig This item: B. However, there can be a range of prices with each type of suspension, so don't assume an expensive high-end sofa has eight-way, hand-tied springs based only on the price point. 50pcs 5 Holes Thick Couch Spring Clips, Upholstery Clips for Furniture Spring Clips, Ek Clips, S Clips Zig Zag Spring Clip, Sofa Chair Spring Repair. 2. Within this seating system are three variations, and each are designed to eliminate sagging and increase firmness. More Info Here. Commonly used in ottomans, chairs (especially seats), auto seats and sofas (seat and back) and take the place of coil springs. Learn more! Check out our helpful high-definition video! You can find it below the products images: How to Measure and Cut ZigZag / No-Sag / Sinuous Springs ***** No-Sag, S-coils What is a Sinuous Spring Sofa Suspension? Best Sofa Springs - Zig Zag Couch Spring - Roger and ChrisShop the best sinuous spring sofa suspension on Roger and Sinuous springs . Source. We love that the upholstery is resistant to stains and water, so it stands up to regular use. Lower quality webbing looks very similar to the high quality version. Coil springs do not break down as rapidly when used by heavier Sinuous Spring at DIY Upholstery Supplies & Charlebois Fabrics. Sinuous springs are designed to offer consistent, resilient support over broad areas, making them a Both zigzag spring, also known as sinuous spring and webbing are commonly used in sofas as suspension. The spring wires are held to the sinuous springs by metal clips; apparently that wire's clips are loose and are allowing the spring wire to get out of place. 273. Buy RINOLO Modern Max Sleeper Sofa Bed - Storage Convertible Couch, Solid Pine Wood, Revolution Performance Fabrics, Sinuous Springs, Made in Europe, Queen Size 90in W x 39in D x 36in H– Pink: Sofas & Couches - Amazon. Ships from and sold by BC Upholstery. These springs are made of steel and are attached to the sofa frame. These wires are attached to the sofa deck This sofa has sinuous spring construction (accommodating up to 993 lbs. com FREE DELIVERY possible on eligible purchases Sinuous Springs, Made in Europe, Queen Size 90in W x 39in D x 36in H Sinuous Spring Seat Support; Solid Wood Legs; Includes Two Accent Pillows; Sectional Dimensions. Sinuous springs, often referred to as zigzag or serpentine springs, are an essential component in the construction of upholstered furniture. This sofa is upholstered in a beige polyester fabric with a textured crosshatch pattern, and features rounded arms, three removable back and seat cushions, curved solid wood House2Home 23" Couch Spring Repair Kit to Fix Sofa Support for Sagging Cushions - Includes 4pk of Springs, Upholstery Spring Clips, Seat Spring Stay Wire, Screws, and Installation Instructions Zig zag furniture and auto upholstery oil tempered sinuous springs 9 Gauge, 10 foot length roll made in the USA. I was a buyer for a furniture chain for 8 years, and bought many items with both sinuous springs and 8 way hand tied. All the upholstery spring kit components are commercial grade, heavy duty It is superior to sinuous springs, the next most common type of foundation found in modern style, high end seating. 5 density foam will keep their comfort for 15+ years. Sinuous Springs No-Sag, S-coils, zigzag wire, zig zag springs, serpentine springs — are all the same thing, but with different names. Also known as sinuous springs, S-springs or zig zag springs, serpentine springs are flat and feature repeating, zig zag curves. 4 %âãÏÓ 1154 0 obj > endobj xref 1154 94 0000000016 00000 n 0000002779 00000 n 0000002939 00000 n 0000007218 00000 n 0000007397 00000 n 0000007522 00000 n 0000007637 00000 n 0000007690 00000 n 0000007855 00000 n 0000007908 00000 n 0000012278 00000 n 0000012391 00000 n 0000016627 00000 n 0000019721 00000 n What Are Sinuous Springs? Sinuous springs are also called zig-zag springs because they are made of one piece of metal bent into a zig-zag. They provide high resilience and distribute weight evenly. Overall: 85. Choosing a couch is a big decision. Sinuous Springs: Sinuous springs, also known as serpentine springs, are S-shaped and run from the front to the back of the chair. 10’ section of 12 gauge sinuous/zig zag spring - hard-to-find chair springs, auto restoration and upholstery products offered exclusively by Spring Down cushions with 1. All the upholstery spring kit components are commercial grade, heavy duty materials giving Swing Anchors 1 5/8" For Sinuous Springs (100 Pack) - Furniture Upholstery Hardware. This sofa’s round arms and tight back complement its glam feel. Spring Down cushions with 2. Plus, its bench seat cushion is removable, so it's a cinch to clean. Well, a sinuous spring suspension, which is a bit of a tongue-twister, is the type of suspension that you most likely have on the sofa that you're sitting on right now. The No-Sag® loop seat springs from Leggett & Platt Home Furniture are a variety of loop seat springs developed with No-Sag® sinuous wire products. com. All of these The process starts by hand fitting springs into the base of the sofa frame. Get it Jan 31 - Feb 4. They consist of individual coil springs tied together in eight directions to create an even and flexible seating surface. While the actual springs remain strong and supportive, the small clips attaching the spring to the internal frame can fail, Well, a sinuous spring suspension, which is a bit of a tongue-twister, is the type of suspension that you most likely have on the sofa that you're sitting on right now. No-Sag® Furniture Clips » No-Sag® Sinuous Loop Seat Springs Woodhaven says that there are two types of sofa springs: serpentine ones, which are round coils, and sinuous ones, which are zig-zagged and flat. See how our furniture pairs with other pieces you‘ve been eyeing - no heavy lifting required. Filled with foam and supported with sinuous springs, it provides a cozy spot for you and your guests to relax. Visit the RINOLO Store. Marketing@HSMSolutions. Sort & Filter. Qty in Cart: 0. springs are tied together to maintain equal and even support throughout the seat. About Us. Its Original, XL Loop, and Supr-Loop springs are engineered and precision-formed to assure a lifetime of trouble-free performance. Recommended. Sinuous spring construction tends to fall in the middle of the price range, while eight-way, hand-tied springs are usually the most expensive option. These S-shaped steel wires are tightly stretched across the frame of a piece of furniture, such as a sofa or chair, and are secured at either end. 0020 New Customer: Sign Up Current Customer? We had a leather, sinuous spring sofa with pocket coil cushions that lasted well over 10 years. 95 Subtotal: Staple Clip for Sinuous Spring Super Clip (100 Pack) - Furniture . The Blue Ribbon spring is the core of the brand’s mission and where they got their name right from the very beginning. Crate & Barrel Bucktown Modular 3-Piece Sectional Sofa. It's typically one of the most expensive and largest pieces of furniture The cushions' sinuous spring suspension coupled with the foam and fiber fill will ensure you never want to get up from the moment you sit down. Sinuous Spring System (No Sag Spring System) Sinuous Springs is a pretty good spring system as well, but only when it is done with high end quality. When you sit down on your couch, you might notice that it bounces slightly, which indicates sinuous springs. It's made from solid and engineered wood, and it rests on black walnut-hued block feet. ), foam cushions, and velvet upholstery. 8" L× 111" W×33. Plus, this The sofa features a Chesterfield silhouette with rolled arms, a tight seat, and an all-over button tufting, giving it a timeless look. This guide will show you the different kinds of spring systems, which one is the best and how to check which spring system your sofa has!8 Way Hand Tied Coil Ultimately, the best way to decide which type of sofa spring is right for you is to visit a furniture store and try out different sofas. This coil spring system is used in brands like Smith Brothers of Berne, Indiana. They are designed to provide support and prevent sagging in seating surfaces such To see if a sofa is eight-way hand-tied, pick up the cushion and push on the seat deck; you should be able to feel the separate springs through the fabric. ADDITIONAL DETAILS Includes two 17"W x 21"H pillows and one 12"W x 17"H pillow. All the upholstery spring kit components are commercial grade, heavy duty materials giving MEICOCO Upholstery Furniture Spring Clips, Sofa Spring Repair kit for Couch, Chair, Sofa Spring Clips Repair Parts 50pk (50) $9. Z-spring seats offer good support and durability while providing a comfortable and slightly softer seating experience compared to coil springs. Furniture Spring Components. Subtracted one star because it is not as safe as it could be- sinuous springs slip off the hook from time to time so keep your face out of the way (trust me, a stretched spring High-strength sinuous spring suspension for long lasting comfort and support; Removable and reversible seat cushions; Loved the shape, fabric, and color of this sofa but had to return it because it was quite a bit shorter than advertised. Sinuous spring suspension tends to feel firmer than eight-way hand-tied. Freda 96'' Upholstered Sofa. Try Our Room Designer Tool Filling: Foam, Fiber and Pocket Spring Filled Seat; Fiber Filled Back. Compared to the other suspension systems on this list, sinuous springs are relatively new. 99 $ 9 . 99 $ 79. 95. Hickory Springs Manufacturing manufacturers top-quality springs, upholstery coils, sinuous wire products, metal components for the furniture industry. It is used on several mid priced pieces at popular retailers like Room & Board and Crate & Barrel . Action Upholstery Supply. A sinuous spring sofa systems consist of heavy-gauge steel wires formed in continuous, vertical S-shaped coils. Like webbing, s-spring sofas are much easier to install. 71. C. Unravel the debate between consistent support, firmness, and durability of platform sofas versus the plush feel, personalized comfort, and bounce of spring sofas. Care: Fabric Sofa, Wooden Legs. 0020 New Customer: Sign Up Current Customer? Z-spring seats, also called serpentine or sinuous spring seats, utilize a series of "Z"-shaped springs that are interconnected. Let’s talk about those. Sinuous Springs: These are pre-assembled to form a continuous S-shaped pattern and are also known as zigzag or serpentine springs. This suspension is made Sinuous springs can be used in both good furniture and bad. Ever wonder how to measure and cut the length of your zigzag / no-sag and sinuous springs? Do want to see an easy way to do it? Then this hi-resolution video is for you! Enjoy!Learn more about zigzag springs and clips Hey there, Furniture with a Heart of Steel At the heart of our upholstered seating is the Blue Steel Spring™ - a patented spring system providing unmatched comfort, support and durability that has been trusted for more than 100 years. Sinuous springs can fail because the majority of the force is placed on a very small portion of the system. The more springs a couch has, and the closer together they are, the more supportive and firmer the seating, according to "Good Housekeeping" magazine. 1. This suspension is made of zigzagging pieces of No-sag springs, also known as sinuous springs or serpentine springs, are a type of spring system commonly used in upholstery and furniture construction. The springs attach to clamps or brackets on a couch and provide support and stability. $1,184. Sinuous Springs. It seems to me that "at rest", the coil spring would not be under any tension and therefor would be more apt to last longer than a sinuous spring A low-profile silhouette along with a wide, spacious frame makes this sofa the ideal spot to hang out for movie night. In this article, we compare their pros and cons. Back springs on Flexsteel sofas and sectionals are made of sinuous wires that add firm support whenever and wherever you need it. Step 3 Remove any broken springs or any springs that no longer arc upward by pulling the nails that affix the spring clips to the frame, using the back of a hammer. 28" sinuous/zig zag spring - hard-to-find auto restoration and upholstery products offered exclusively . No-Sag® offers springs in three different variations to suit the requirements of different styles, applications, and economies. if you feel in any way unsatisifed, please contact us via Amazon, we will try our Coil Springs: Coil springs are cylindrical and found in many upholstered chairs. Foam-filled seats also feature sinuous springs to give you On the other hand, sinuous spring sofas are the most common suspension systems in low to mid-range priced sofas. The bouncy feel provided by these springs can enhance your sitting experience by preventing sinking or discomfort over prolonged periods. A quality sinuous spring couch has at least five serpentine springs per seat cushion. It's pretty common, it's no offense, but it's probably the cheapest type of suspension out there for furniture. Versatile, easy to install sinuous spring will provide both comfort and firmness; Professional grade 8 or 9 gauge tempered steel springs for cushion bottoms (medium-firm feel) The Palliser Alula (77427) leather sofa set has a Sinuous Spring seating system, a kiln dried hardwood frame, and is made in North America. Upholstered in a plush Royale Dijon velvet, this piece features walnut legs and a classic channel-back design. Sinuous Springs: Also called serpentine springs, they are S-shaped and run from the front to the back of the seat. You’ll probably come across the term sinuous springs more than eight-way hand-tied, since it’s the most common suspension in low-to-mid-priced sofas. 5 Great sofa. 280. 71 . $14. 5" H Danca Furniture, 11201 Bass Pro Pkwy, STE N111, Little Rock Arkansas 72210, United States. Coiled springs can often be bent back into shape with pliers and then reattached with the correct tension. Nailhead trim accents the edges, enhancing the sophistication of this piece. 8-Way Hand Tie. Sinuous Springs: Also called "zig-zag" springs, these are S-shaped and run horizontally across the frame. Drop-in coil springs are a less labor-intensive version of other types of spring suspension; coils are mounted on a metal frame, which is then added to the furniture as its own single unit, rather than being attached directly to the furniture's frame. Sofa Suspension Types Which Is Better. Sinuous spring construction on seat and back ; Fiber encased foam seat with Coil spring seat ensures seating comfort ; Raised, shaped headrest keeps head elevated even in a full recline position ; Outside seats of Sofa fully recline with the pull of a lever ; Padded back and arms ; Manual motion mechanism on the outside arm of the recliner Swing Anchors 1 5/8" For Sinuous Springs (100 Pack) - Furniture Upholstery Hardware. DIMENSIONS 90"W x 36"D x 31"H One of your spring wires is slipping sideways and poking your upholstery. The springs on a modern sofa are usually zigzag wires, called sinuous springs, installed with a slight arc from the back wall of the sofa frame to its front edge. Sinuous springs clamp to each of the front and back rails of a chair or couch in parallel. Unlike sinuous wire springs, our springs never There are many factors that determine whether a sofa is good quality; a few examples are upholstery materials and construction. Measuring Zig Zag springs is done by determining the pitch, or the number of "U" shapes present. They are made using an S-shaped spring, or thick-gauge wire bent to create a recurring S-shaped pattern. 99. Sort by. $8. 99 Get it as soon as Tuesday, Jul 30 Sofa springs are one of the most important factors of a sofa’s comfort and should be of the highest quality for the most comfortable, supportive and long-lasting piece. Sale +1 Option Available in 2 Options. Jackson Catnapper uses pocket coils cushions and sinuous springs, and goes a step further with a steel box spring frame, and Sinuous Spring at DIY Upholstery Supplies & Charlebois Fabrics. It is extremely low cost for A sinuous spring sofa or chair should be considerably less in price that an 8-way hand tied unit. Color: Green . Coil Springs: These are individual springs secured to the webbing or tying together to form a spring network. Home; All Products; Living Room; Bedroom; Mattress; Dining; Also known as Sofa Springs, Chair Springs, Sinuous Springs, Serpentine Springs or Snake Springs. Sinuous-spring are easy to remember because they're simply S-shaped springs set in zigzagging rows within the foundation of the seat. 71 $ 1,184. how to fix sagging busted sofa couch springs with one quick easy solution using only a pair of vice grips 【Secure attachment】-Upholstery Spring Clips provide 4 separate holes for screws, nails, or staples to securely attach zig zag sinuous no sag springs to wood frames of upholstery furniture. Most people, however, find the 8 way hand tied to be generally more comfortable. Platform foundation system resists sagging 3x better than spring system after 20,000 testing cycles by providing more even support; Smooth platform foundation maintains tight, wrinkle-free look without dips or sags that can What is a Sinuous Spring Sofa Suspension? Best Sofa Springs - Zig Zag Couch Spring - Roger and Chris Shop the best sinuous spring sofa suspension on RINOLO Modern Carmella Sleeper Sofa - Storage Pull Out Sofa Bed Pocket Sinuous Springs, Pine Wood Frame, Velvet Upholstery, Sleek Arms, Made in Europe, Queen Size 85in W x 39in D x 35in H – Green . 【Versatile use】-This couch spring repair kit can be used for fixing either the seat or back springs of furniture such as sofas, car seats, and more. The disadvantage of a sinuous spring is that it can fail since a lot of weight lies in a small portion of the whole system. T Sinuous springs. Sinuous spring is produced in rolls and is cut to length as needed. Soft, or 11-gauge, sinuous springs are meant for chair and sofa backs. How often Showing results for "sinuous springs sofa" 45,939 Results. Cover Type: Removable Seat and Back Cushion Covers. Different types of sofa springs like sinuous springs or coil systems cater to varying preferences for firmness and cushioning. Sinuous springs are typically supplied in gauges 8 to 11 GA wire. Package of 100. 1-5/8″ Swing Anchors for use with sinuous springs. 4. Coil Springs: Found in older or high-end furniture, these are coiled vertically and provide firm support. It includes 4 no sag springs, 12 spring mounting clips, 20 feet of springing wire, 20 stay wire clips, and step-by-step instructio House2Home 25" Couch Spring Repair Kit to Fix Sofa Support for Sagging Cushions - Includes 4pk of Springs, Upholstery Spring Clips, Seat Spring Stay Wire, Screws and Installation Instructions. 662. Along with clips and fasteners, the springs are attached to the sofa’s frame by metal tie rods, Sinuous springs. Now 57% Off FIX SAGGING CUSHIONS - Our couch spring replacement kit includes all the parts you need to reupholster a new chair, sofa or fix that sagging couch support. Its sinuous-spring seat construction supports three back and seat cushions. Home. In Stock. Zigzag springs, also known as sinuous springs, are a popular choice for sofa construction. Sinuous Springs Vs Eight Way Hand Tied The Stated Home Blog In this video Bill will show you how to determine the gauge of the springs, what clips are used to attach to the frame and how to install a new zigzag sinuous spring. The back cushions are removable and reversible, so it's easy to fluff them up when they need a refresh. Bring classic design to your living room with this Bridgewater-style sofa. $79. Suspension: Sinuous Spring. top of page. These springs have a zig-zag pattern and sit in rows. The Alula (77427) leather sectional collection has curved The Delphine Sofa is the added touch of mid-century modern charm you've been seeking. Firm sinuous springs -- 8 or 9 gauge -- work best for seats and ottomans. This unique spring system is used exclusively in Flexsteel products. Discover the ultimate guide on platform foundation system sofas versus spring-based sofas. Sinuous Wire Suspension (Good) Also known as no sag, it is the most common suspension system out there. Various Types Of Sofa Springs Furniturestop Co. Drop-in coil springs 10’ section of 9 gauge sinuous/zig zag spring - hard-to-find auto restoration and upholstery products offered exclusively . You need two clips to attach each spring to the frame, spaced roughly 2 inches apart. 99 $ 8. Long considered the gold standard of sofa suspension, eight-way hand tied is the most labor-intensive and costly option. 00 $ 26 Zig Zag springs, also referred to as sinuous, serpentine, or no-sag springs, are a comfortable and easy-to-install seating option. 8-Way Hand-Tied Springs - 8-Way Hand-Tied Springs: These are often considered the gold standard for sofa construction. The craftsperson then hand ties the springs together, using eight knots tied on each spring (hence the name "eight-way" hand tied). Diffe Types Of Sofa Springs. Upholstered in the fabric and hue of your choice, this sofa easily matches your room's current style and color scheme. Different name, same springs and clips! Easy to install. These springs are very easy to use and are great for ottomans, chairs and sofas Durable, no-sag zigzag springs that provide silent support for your furniture cushions. xtnqw ysul knvy ske vjtyq acr upbt msquz hanxj tbyb rnhli giewfbov ute oqjks eifqf