HOW TO SOUND PROOF YOUR CAR? SOUND BLOCKING TIPS AND MATERIALS
Types of Sound Insulation / Sound Proof
Sound insulation for cars comes in three basic forms:
– these comprise foam rubber backed on one side by a woven cloth (or aluminised polyester) and on the other with pressure adhesive. As the name suggests, they’re suitable for mounting under bonnets and also under bootlids.
– these materials use compressed layers of cotton-waste (or similar) sandwiching a thin layer of bitumen. They’re used both to absorb noise and also to prevent noise transmission. They can be mounted on the firewall within the cabin (ie under the carpet), under the boot carpet and behind the rear seat in booted sedans. This noise insulation is held in place with applied contact adhesive.
– these insulators comprise low resonance (acoustically ‘dead’) materials which are designed to stop panel vibration. In use they’re glued to the panels. It is important that the join between the insulator and the panel is continuous, with large amounts of contact adhesive therefore needed.
What is Sound Proofing? How Can I do It In With My Car?
Sound Proofing starts with some means of damping. A number of products are available for this, and they all have various degrees of effectiveness. The best results are always obtained from using a combination of these products. There are mats, sprays, foams, and insulation available from a number of manufacturers
Mats are usually either Styrene-Butyadine-Rubber or asphaltic sheets backed with an adhesive of some type (although other materials are used in some cases). Installing mats in your vehicle is a simple way to reduce vibration, and is effective as well. The way mats work is that they are used to cover panels. The material they are made of absorbs vibrations in the panels, and turns them into heat, or it may simply lower the resonant frequency of the panel. Mats can also be placed between panels to reduce the amount of vibration between the two panels when they are in close contact. Many times, the mats will also have a metal foil backing to improve the heat resistance of the matting (thus allowing you to use it in an engine compartment). The matting also adds weight to a panel, reducing it’s tendency to vibrate in the first place. Some of the more popular mats are Dynamat and Road Kill, but there are alternatives.
Sprays are also used for damping. These sprays normally come in a professional can, which require a compressor and paintgun to apply, but many companies are starting to market aerosol cans of sound deadener spray. The spray is often used in places where matting would either be too difficult, or would add too much weight/bulk. Door panels are the most common application for sprays, as well as highly irregular crevices (like inside kickpanels). Sprays are suitable for large panels as well, but they tend to be messy, and require taping/masking off of upholstery and windows.
Foams come in two forms: Sheets of foam, and foam sprays. The sheets of foam are used much like mats are; They are laid over panels to reduce and absorb vibration. Unlike mats, which absorb the vibration and convert it to heat energy, foam sheets disperse the vibrations throughout, reducing its total energy. Foam sprays are used to fill in crevices. As they dry (or rather, cure), they expand slightly, pressing against the nearby panels. The individual cells help to disperse energy away from the vibrating panel, and absorb them. Foams can be expensive as well, and there is a low cost alternative here, as well. The first is Styrofoam©, which can be obtained in a spray can. Styrofoam© is the brand name for the polystyrene foam we are all familiar with (and somewhat annoyed by at times). The fumes given off by Styrofoam© are noxious, and many communities have laws banning its use due to environmental concerns. Another alternative is insulating foams like Great Stuff©, which is used in home construction. Great Stuff© is cheap, fireproof when cured, and readily available at any hardware store for about three dollars a can. Great Stuff© is also shapeable when it cures, and can be used to smooth sharp corners. The downside to Great Stuff©, like Ice Guard, is that it is messy. Once Great Stuff© is sprayed on upholstery, your clothes, your skin, etc, it’s all over. You hands will be stiff and sticky for days, if not weeks, and your clothes are forever ruined. Great Stuff© also expands voraciously, so spray it carefully.
Finally, there is insulation. Jute is the most common insulation. It is laid under carpets in both cars and houses, and is basically a thick mat of fibers which absorb sound. Though less effective than the other methods, it adds a plushness to carpets, and has very good thermal insulation. Micro Jute is recommended, because it’s much thinner than jute, and has about the same level of effectiveness. Jute or Micro Jute can be gotten from a number of manufacturers, and is available at any carpet supply store.
DIY NOISE BLOCKING TIPS IN MALAYSIA
First of all sponge is not gonna work. If you want to DIY super cheap, get the Insuflex from KHGuan (I think RM15+ a large sheet) and cable tie the thing (or glue it). If you want a medium alternative go to KFAudio and ask them to use Sikadamp (RM30 a piece) or go to Soundblok and ask them to quote on their stuff. If you want ultimate dampening get Dynamat Extreme which sells from RM60 to RM100 a piece and front doors only required 3 pieces to cover (meaning approx 6 to 7 pieces for 4 doors).
Otherwise mix and match. Doors use Dynamat, floor use soundblok, roof use Insuflex, bonnet use Insuflex, Boot use Dynamat.
Up to you.. it’s all good.
As for rust, there’s no guarantee on the glue whether it’ll rust or not. But Dynamat, Sikadamp, soundblok and many of those bitumen-based-stick-on stuff don’t cause rust. Insuflex is just a spongy type of material and needs to have something to keep it there.
That audiotech fischer stuff is good stuff too. But obviously for that price you have many other options. The most important difference is that paste is not removable. Dynamat extreme and Sika and all are removable.