What does the WARRANTY cover?

DUNLINE® Rubber Products Company warrants all DUNLINE® Rubber Belts to be free from manufacturing defects in materials or workmanship or we will replace or help to repair the belt at no charge per our sole discretion. If neither of the foregoing are reasonably available, we will refund or credit the net belt price less the amount attributable to its prior use.

This warranty is valid only if the product, in part or in whole, at our request, is returned for analysis in its original shipping container. No claim will exceed the invoice value of the product. Any additional payments will be at the sole discretion of DUNLINE® Rubber Products Company.

(See Dunline Advantages – Warranty)

What SHIPPING options are available?

Manufacturing Lead-times may change but are typically 3-4 weeks after receipt of a signed Purchase Order and/or receipt of Payment.

What are the expected shipping LEAD TIMES?

Lead times change, but are typically 3-4 weeks.

What are the TERMS OF SALE?

    NOTE: It is imperative that the proper Banking information be used to ensure we receive the payment in our Pittsburgh, Pa. account ending in 0425. We will not be held liable for deposits made to any other account.

*NOTE: There is an associated charge for a CAD AND L/C payments to offset all incurred Banking Fees, please contact your local agent for details.

Are SAMPLES available?

Yes, we welcome the opportunity to provide you with samples. Please contact us at beltinfo@dunline.com with your sample requests

What THICKNESS of rubber belt is suitable for our process?

The ideal thickness of the belt depends on the fabric being processed and the required shrinkage. As Rubber Belts become thinner, they lose their ability to effectively shrink. This is because a thinner Belt has less surface movement and thus, less recoil action.

  • 67 mm: recommended for most customers process.
  • 72mm: the thickest belt recommended for processing the heaviest weight fabrics (such as 550 G/M2 denim) requiring shrinkage as much as 16%.
  • 50-55mm: Recommended in mills running lightweight fabrics primarily for hand and on COMFIT machines.

NOTE: DUNLINE has been making the COMFIT RB longer than any other vendor. As such, we have a wealth of information on how best to produce this belt and can offer a special surface to help prevent fabric discoloration after processing.

Which FELT TYPE is best for my application?

  • 100% POLYESTER
    The industry standard. This special polyester has particularly excellent abrasion and tensile characteristics as well as hydrolysis resistance and is ideal for use when the pH level is acidic to neutral (pH under 8).
  • 70/30 and 50/50 POLYESTER/ACRYLIC
    This is the preferred felt for applications that tend towards an alkaline pH level.  It contains special hydrolysis resistant polyester fiber (see above) with excellent abrasion resistant and highly alkaline resistant acrylic fibers.
    Many customers prefer this type felt to impart a superior “hand” to any fabric processed
  • 100% NOMEX®
    The ultimate in felt performance and the only option for use on a Liquid Ammonia range.  Specifically engineered to perform in all high temperature and chemical environments. It is the ideal felt for commission finishers processing a full range of fabrics with various pH levels


Agents are strategically located throughout the world to provide prompt delivery and service. Please click here for the name and address of a DUNLINE Agent near you.

How do I PROLONG the LIFE of my rubber belt?


When and how do we GRIND our rubber belt?

In general, you should consider grinding the surface of the Rubber Belt if any or all of the following conditions exist:

  1. Rubber Belt hardness varies more or less than 10% (15% maximum) of its original reading. (NOTE: If forgotten or unknown, this original reading can be approximated by checking the hardness of the Belt on its edge, as this area does not come into direct contact with the heated steam cylinder and finishing chemicals.)
  2. The surface of the Belt becomes shiny or glazed. In this condition, the belt loses its grip on the cloth and thus, its ability to effectively carry water.
  3. Penetration of chemicals and finishes in the surface of the rubber that reduce the natural ability of the Belt to shrink fabric.
  4. Surface cracks or other blemishes on the face of the Belt. These will worsen if not removed. We strongly recommend immediate action.

REMEMBER: IT IS BETTER TO GRIND MORE OFTEN THAN NOT ENOUGH. If properly ground, and ground at the optimum time, a more frequently ground Belt will not only outperform an infrequently ground one, but will also last longer.

 How to Grind see: Technical Support -> Grinding

When should we WASH our rubber belt?

All rubber belts should be washed after every grinding and whenever build-up of “sizing” accumulates on the belt’s surface.

  • Belts need to be washed after grinding to remove “surface tension” and allow cooling water to adhere to the belt’s surface. This is important to prevent surface cracks.

Chemicals and finishes from the fabric can accumulate on the surface of the belt reducing the rubber’s ability to shrink fabrics. A number of factors influence this build up, and experience is the best guide to determine how frequently the belts must be washed to remove it. Please contact Dunline for advice specific to your fabric processing needs at beltinfo@dunline.com

How do we determine proper rubber belt TENSION?

Fine tuning the correct amount of tension on a Rubber Belt is largely a function of experience. Several variables, including the current thickness of the belt, the style of fabric being processed, etc., need to be taken into account for an accurate determination.

In general, however, the proper tension on a 67 mm (2 5/8″) thick Rubber Belt can be approximated as follows:

  • With the rubber blanket tension set at the minimum position, draw two (2) lines*, 30.5 cm (12″) apart, on the edges of the blanket. Make these lines on BOTH belt edges, that is, on both sides of the belt.*NOTE: On a new DUNLINE® Belt this has been done for you, although, with wear, the marks may need to be reapplied.
  • Increase the tension evenly, until both lines are 31 cm (12 1/8″)apart to a maximum of 31.3 cm (12 1/4″).
  • Turn the belt (4 – 5) complete revolutions. Stop the machine with the line markings between the tension and guide-rolls. Confirm that the amount of stretch is still 31 cm (12 1/8″) preferably, to a maximum of 31.3 cm (12 1/4″).
  • Start processing fabric.

*NOTE: Thinner Rubber Belts, 51 mm (2″) or less, may need up to 8 mm (5/16″) additional stretch per each 30.5 cm (12″).


If the fabric shows any corrugation, it may be necessary to increase the tension or stretch slightly.

Have a worker on each side of the tension roll tighten or raise the tension roll one turn at a time, while watching the fabric. As soon as the corrugation disappears, increase the tension by one more turn.




Too much tension reduces the relative compression that exists on a Belt. In essence, a tighter belt means less recoil and less potential shrinkage. Excessive fabric tension can exist in many different areas throughout the machine set up, but is generally at fault in the following areas:

  1. Between the A-Frame or J-Box and the Sky House or Cole Spray (Moisturizer).
  2. Between the Moisturizer and the “nip” area of the Rubber Belt.
  3. Between the Rubber Belt and Palmer units.
  4. Between the exit end of the Palmer and the take up roll on the exiting A-Frame or J-Box.

REMEMBER: A SANFORIZING machine is meant to shrink cloth, not stretch it.

NOTE: The use of a shrinkage indicator (a transducer connected to a shrinkage monitor) at any critical point mentioned above is beneficial in determining whether or not shrinkage is being pulled out at that particular point.

For the proper way to tension your belt please see: “Technical Support Tension”

How do we CALIBRATE our compression plate?

Be sure to calibrate this setting after the installation of a new Belt and after every grinding session. Without proper calibration, it’s difficult, if not impossible, to know how much compression is actually being applied to the Belt. Obviously, if insufficient compression is being applied, the result may easily be less shrinkage than desired. Conversely, excessive compression will degrade the rubber surface faster, shortening belt life. Please see our instructions on how to properly Calibrate The Compression Plate in  “Technical Support Calibration of Compression Rolls”

Is it possible to REPAIR our rubber belt?

The answer to this question obviously depends on the severity and type of problem and, sometimes, what odds one is willing to take. Some patches, for example, are a high risk, but, nonetheless, still performed as the Belt has a lot of useful rubber remaining.

  • Surface Cracks: If the cracks are small they may be ground away. Ensure that proper settings and adequate water are cooling the belt to prevent further cracking. If cracks are somewhat larger they may be patched.
  • Edge Cracks: Cracks or cuts on the edge of the belt may be addressed through hand grinding, trimming, and/or patching. Please contact us with pictures of the damage so that we may advise on the best solution.
  • Interior Cracks: If caught early these may be hand ground away.  Interior crack are difficult to patch but if they get larger this is required to maintain useful life of the belt. If the crack gets larger patching is required, but if the cracks are numerous
  • Burns: As the belt is made of natural rubber, it is susceptible to being burned if not properly cared for – particularly if it is left resting against a hot steam cylinder. The only solution for a burn is to grind. Hopefully the burn is not so severe that a grinding cannot rectify the damage.

For directions on how to best treat each form of crack please see Technical Support Patching / Cracks.

Are TRACKING PROBLEMS correctable?

Tracing Problems in Rubber Belt

It is always best to follow our Installation Instructions from the start. Otherwise, irreversible damage may occur. PLEASE do not hesitate to contact us with your questions at the start of a problem rather than after it’s potentially too late for us to help.


DUNLINE Rubber Belt tracking problems are virtually non-existent. Should a problem occur, however, please check the following for possible remedies:

  • Bearings.
  • That all cylinders are parallel to the heated cylinder and turn freely.
  • That there is no build up of any type either on the cylinders or the inner surface of the belt.
  • That no grease or oil exists on the belts inner surface.
  • That the belt is not wider than the carrying rolls.
  • That sufficient Tension has been applied.
  • Check either side of the belt for edge cracking; multiple cracks on either or both edges can affect tracking. If necessary, trim the belt too remove the cracks.

If, after checking these variables a problem still exists, please do not hesitate to contact us via one of the following options: TEL: 1.843.374.3102; FAX: 1.843.374.3104; or e-mail beltinfo@dunline.com

Tracing Problems in Palmer Felt

It is always best to follow our Installation Instructions from the start. Otherwise, irreversible damage may occur. PLEASE do not hesitate to contact us with your questions at the start of a problem rather than after it’s potentially too late for us to help.


Keeping this rule foremost in mind will help when trying to determine, through the process of elimination, which variable(s) may be causing the felt to track improperly.

Please triple check the following:

  • That all rolls have been reinstalled, correctly pinned or bolted, turn freely, and are parallel to the heated cylinder.
  • That the pistons used to engage the tracking roll are properly working.
  • That the feeler gauges or tracking sensors are working properly.
  • That the felt is not too wide, thereby hanging over the cylinder(s) edge(s).
  • That there is enough heat in the main cylinder to create sufficient friction such that the felt holds to the heated cylinder as opposed to slipping against a cold cylinder (352° C / 200° F).
  • NOTE: We highly recommend that you take a few moments before installing a felt to measure the length (see diagram below). Please compare your figures to ours provided on the Certificate Of Analysis enclosed with the packing slip. Should a discrepancy exist, please call before installing.

If, after checking these variables a problem still exists, please do not hesitate to contact us via one of the following options:  TEL: 1.843.374.3102; FAX: 1.843.374.3104; or e-mail beltinfo@dunline.com

What causes the rubber belt surface to become STICKY?

The surface of a Rubber Belt can become sticky or gummy in the “selvage” area, or the area outside of the cloth line. This usually occurs for the following reasons:

  1. Improper and/or Infrequent Grinding – After periods of prolonged use, the surface of any Rubber Belt tends to deteriorate because of the effects of finishing chemicals, heat and compression. Usually, this deterioration results in a softer Rubber surface (as measured using a Shore A durometer). It is especially prevalent in the area of the Rubber Belt outside of the cloth line. This area is more susceptible to problems because the natural rubber is directly exposed to the heated steam cylinder.If this softer or “dead” rubber is not ground away, it has a tendency to become sticky (as the rubber is actually reverting back to its original “gum” state) and, eventually, will begin to “peel” or “pick” away in sheets or pieces from the surface of the Belt. At this point, the Belt obviously needs immediate grinding.* See our recommended Grinding Instructions for guidelines as to when and how to properly grind a Rubber Belt.
  2. Excessive Temperature– Temperatures in excess of 290° F (145° C) will speed up the deterioration process of the rubber.
  3. Lack of Water – Improper application or lack of water is a common cause of a sticky or “gummy” Rubber Belt.

NOTE: Make sure that all water spray pipes are operating properly and check the condition of the felt or brush doctor blade. Please see additional comments found under FAQ: Why does our Rubber Belt Crack? Or, contact us for help via e-mail: beltinfo@dunline.com ; PH 843-374-3102; Fax 843-374-3104.


What causes a felt to SHED fibers?

There are typically three explanations: 1) the Felt manufacturing process, 2) the application the Felt is under, and/or 3) the type fiber used to manufacture the felt is not suitable for the application.

The Felt Manufacturing Process : requires a set “needling” procedure to insure interlocking of the fibers so they will not “pull” out or simply “lay” on the surface.

In addition, the “density” of the felt can be too great, not allowing proper set of the fiber. Check with your supplier/manufacturer by furnishing them the Felts serial number.

The Application : under which the Felt is used may not be suitable for the type Felt being used. For example, certain applications, such as “polishing” require the Felt withstand much more abrasion than other applications, such as conveying or SANFORIZING. We suggest checking with us to insure the correct fiber is used to manufacture the Felt being used in your application.

The Fiber Type : used to manufacture the Felt may be incorrect either for the application or for Felt manufacturing. Obviously, certain fibers withstand certain elements that others will not. One fiber type may perform exceptionally well at 175° C (347° F), while another becomes brittle, breaks, and sheds. Or, certain finishes, like silicone, may have been used on the fiber allowing it to be too slippery and shed. Another consideration may be the length of the fiber staple – too short and it resists proper locking during the needling process.

The importance of selecting the correct fiber for a specific job application and working with a quality manufacturer, can not be ignored. We welcome the opportunity to lend our expertise in this selection process. Please contact us by any of the following means for support: Tel: 1- 843-374-3102; Fax 1-843-374-3104 or e-mail us at beltinfo@dunline.com