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Troubleshooting Guide


Here are some typical problems with vacuum-formed shapes:

Soft and Weak Pieces

Longer Forming Time

Rough Back Side

Slow Drying

Poor Floc, Cloudy Water

High Temperature Shrinkage


Problem Possible Causes Problem Remedy
Soft and Weak Pieces
Starch + Colloidal Systems
Too little starch •Check weight or volume of starch used
•Increase starch in formulation
Bacteria eating starch
(you will smell this!)
•Clean out system with Clorox to kill bacteria and treat water like swimming pool to keep bacteria-free
Increased fiber size:
length and/or diameter
•Chop fibers longer or add some chopped fibers to formulation
•Consult with fiber supplier
Too high colloidal silica to starch ratio •Optimize by using less small particle colloidal in formulations
•Use larger particle size colloidal for greater strength
Starch inconsistency •Try a different pallet and lot number
Filler content •Check size and weight of filler used
Wesil Binder Systems
Too little binder •Check weight added; try 10% more and monitor forming time
Filler content •Check weight, size, and quality of filler used
Errant Wesil Binder •Try a different pallet or lot number
Longer Forming Time
Smaller or shorter fiber •Try fiber from different pallet/bag
•Consult with fiber supplier
Filler too fine
Too much filler
•Check weights and filler anaylses
•Use coarser filler, 100-120 mesh preferred
•Try 48 or 35 mesh to open it up
Too much binder •Check weights and silica:starch ratio
•Reduce starch by 10%
•If using Wesil binders, reduce by 10%
Clay in formulation •In general clays like bentonite increasing forming time
•Do not use clays with Wesil binders
Rough Back Side
Over floccing
slurry too concentrated
•Reduce starch and/or increase colloidal silica to increase the silica:starch ratio
•Run lower fiber content in slurry
•If using Wesil binders, reduce level by 10%
Slow Drying
Poor de-watering •Reduce starch and/or increase collodial silica to increase the silica:starch ratio
•If using Wesil binders, reduce level by 10%
Clay in formulation •Clay tends to hold water
•Check weight used and reduce level by 10% if possible
Oven conditions •Dying above 250°F degrades starch
•Low humidity gives fastest drying
•Need more air circulation early in drying cycle
Poor floc, cloudy water
Too little binder •Check to ensure correct amount of colloidal silica was added
•Increase colloidal silica by 10% to see if floc improves
Starch inconsistency •Try a different pallet or lot number
•If pre-dissolved, make up a fresh batch
White water problems •If using recycled white water, check for excess colloidal and starch in white water
High temperature shrinkage (reformulation)
Wrong fiber •Use a higher temperature fiber
Wrong binder •Use larger particle size colloidal silica
•Try a colloidal alumina binder
Wrong filler •Use mullite (high alumina content) or alumina filler
If you still have a problem and would like expert technical assistance, give us a call or follow this link and describe your problem. We'll get back to you to help you determine a solution.
Tech Help

WesBond Corporation

1135 East 7th Street

Wilmington, DE  19801

phone (302) 655-7917 fax (302) 656-7885 

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