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Spectrum™ Sludge Deadener

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Spectrum™ Sludge Sound Deadener.

Looking for a sound deadener to help create a bubble of comfort inside your vehicle? The first step is a liquid sound deadener like our Spectrum Sludge, the thickest noise and vibration paste on the market. Ordering Spectrum Sludge still gets you the Spectrum product, but we also include a bottle that contains our "Activator" formula. By stirring in the activator to Spectrum, the viscosity changes from comparable to chocolate syrup to more like peanut butter. All engineered to absorb vibration energy and reduce the transmission of structure borne noise in vehicles.



  • High heat, water based viscoelastic paste
  • Choose your thickness. Apply 1mm per layer (recommended: 2-3mm total thickness)
  • Excellent for hard to reach parts of your vehicle (undercarriage, wheel wells)
  • Comes with 2 containers – 1 gallon of Spectrum and 1 bottle of Sludge Activator
  • Temperature rated up to 400 F
  • Apply with a putty knife, trowel, or gloved hand
  • Made in the USA



 Size Options   1 gallon, 5 gallon
 Square Foot Coverage  20 sq ft per gallon at 2mm thickness
 Total Thickness   Recommended 2-3mm, max 5mm
 Layer Thickness 
 Apply in 1mm layers
 Weight   11 lbs (cured), 14 lbs (wet)
 Water Resistance   Waterproof and rustproof
 Temperature Resistance   400°F
 Application Temperature   Above 50°F for first 24 hour dry period 
 Primer Required?  Shiny/waxy surfaces will require a primer 



 Spec Sheet   Spectrum Sludge Product Spec Sheet 


Material Testing

Acoustic Loss Factor @ 200Hz

 Temperature  23°F   50°F   77°F    104°F    131°F 
 Spectrum (2mm)   0.037   0.083  0.215   0.105   0.034 
 Spectrum (3mm)   0.066  0.119   0.363   0.258   0.068 
 Spectrum (5mm)   0.081   0.165   0.534   0.379   0.093 


 Tested Properties   Performance 
 Color  Blue (wet), Black (cured)
 Viscosity   4000 centipoise 
 Specific Gravity   1.45 
 Max Temperature   400°F 
 Solubility   Soluble
 Odor   None (when cured), Mild (as solvent) 
 Flammability   Self-extinguishing
 Water Resistance   Waterproof
 Shelf Life  1 year (unopened), 30 days (opened) 


Product Usage Tips

  • Clean up with water within 30 minutes of application. Do not wait longer or Spectrum Sludge will dry.
  • If applying multiple layers of Spectrum Sludge, wait 30-60 minutes for the product to cure and change color from blue to black.
  • It must be above 50°F for the entire 24 hours cure period after applying Spectrum Sludge. Dry times increase with low temperatures and high humidity. If you expect longer than usual dry times, we recommend thinner layers (0.5mm instead of 1mm) to the same total thickness.
  • Spectrum Sludge is designed to adhere to metal. Do not apply to plastic or fiberglass without the proper primer. If applying to a high gloss wax coat, you must sand down and apply a primer.
  • Do not freeze Spectrum Sludge! If it does freeze, do not mix, shake, or move until it has completely thawed.
  • Wait 24-36 hours (depending on humidity) before putting upholstery back in the vehicle. Wait 7 to 10 days before applying a bed liner.
  • As Spectrum Sludge cures, its deadening properties will continue to increase. Vibration damping doubles from 4 hours --> 48 hours, and continues improving for 7 days.
  • Spectrum Sludge is not a bed liner. Even after it has cured, it can be damaged by heavy impact.
  • Shelf life of 1 year when stored at room temperature


Installation Instructions


  1. After upholstery or carpet is out, remove loose debris, rust, dirt, and waxy oils to insure a solid contact surface. Most new cars will not need much prep work, while some older vehicles should be treated with denatured alcohol.
  2. Spectrum Sludge is a two-part system. The first part is a bucket of our original vibration coating, Spectrum. The second part is a 6 oz bottle of Sludge activator – the catalyst that turns Spectrum into the sludge-like paste. The more activator you add, the thicker Spectrum gets.
  3. Slowly mix one 6 oz bottle of Sludge activator for each gallon of Spectrum while stirring rapidly. A paddle mixing drill bit will work best. Do not mix the entire bottle of Sludge activator all at once. The entire process should take about 90 seconds while using an electric paddle. If mixing by hand, the process should take about 5 minutes.
  4. Once thoroughly mixed to a consistent viscosity, apply Spectrum Sludge to the metal surface. It must be applied at least 1mm thick to properly deaden the metal. We generally recommend a 2 or 3mm thick total application thickness. At 2mm thick, a gallon will cover about 20 square feet.
  5. Do not apply more than 1mm in one layer. Spectrum Sludge will skin over and turn from blue to black over 30 to 60 minutes depending on the temperature and humidity. Additional layers can be applied after it has changed color to black.
  6. Spectrum is easy to clean up with water if done within 30 minutes of applying the product.
  7. Allow 24-36 hours before another product or upholstery is installed. Spectrum Sludge may be covered with a bedliner after 10 days.


Common Product Uses 

  • Spectrum Sludge can be used for any of the applications you'd use the Spectrum Spray on Deadener. The performance is the same, but the method of application is different.
  • Personal vehicles (interior, undercoating, wheel wells)
  • Commercial vehicle fleets
  • Elevator shafts