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Technical Questions 

VG12: What is the difference between cure time, set time, open time etc?

Clamp or Set Time - The amount of time that the laminated panel will need to be pressed.

Shelf Life - The length of time that a product can sit unused and unopened.

Open Time - The amount of time between when you apply the glue and when the material is placed in the press.

Cure Time - The amount of time that it takes for the glue to fully harden.

Pot Life - The length of time during which a glue can be used after it is mixed.

VG6: What can be done to prevent the veneer from curling up as soon as it´s laid onto the glue and substrate?

Veneers have a tendency to curl up quickly when they are placed upon a glue-prep´d substrate. Veneer softener won´t work and sometimes sprinkling the top surface with water creates problems in and of itself.

I use a few small pieces of masking tape to hold the edges down. I attach a few strips to the top edge of the veneer before putting it on the substrate. Then I press the tape around the edges of the substrate as soon as I put the veneer down.

VG11: How much glue should be applied to the veneer?

The key to applying glue is to put it on evenly. The rule of thumb is that the surface of the substrate should look evenly painted with veneer glue. I´ve found that, by far, the easiest way is to use a dedicated glue roller. A good test to see if you have applied the correct amount of glue is to place a pencil mark on the substrate and apply the glue. If you can barely see the pencil mark on the substrate (through the adhesive), you have the right amount of glue.

Questions according to category 

Contact cements

Floor covering adhesives

Industrial contact adhesives

Specialty adhesives 

Contact Cement 
What are the problems in sticking veneer or Formica? 
Parts of the glued laminate surface start to lift off

Reason: Insufficient glue has been applied. Solution: Apply more glue to both surfaces, which should be well covered with a glue layer. 

Reason: Pressing the two surfaces together too early (and thereby preventing the thinners from escaping). Contact glue contains thinners to ensure easy spreading. However these have to evaporate first before the glue achieved its full adhesive strength. Solution: Extend drying time so that each side has a reasonable dry touch before pressing the two surfaces together.

There are bubbles under the Formica or veneer

Reason 1: Insufficient pressure has been applied to the veneered surface. Solution: Increase pressure gently, ensuring that all areas are covered. 

Reason 2: Thinner is trapped between two surfaces. Solution: Extend the drying time for each surface before pressing them both together.  

Reason 3: Bringing the surfaces together and applying pressure was not done in a smooth and continuous way. Solution: Press from the center and radiate out toward the edges. 

Reason 4: The glue was spread out unevenly. Solution: Check how the glue was applied. It is recommended to use a special trowel with serrated side edges, which leaves uniform ridges of glue along the whole surface without leaving and excesses of glue.   

Reason 5: Uneven pressure on the surfaces. Solution: Check how press is being applied. If necessary, enhance pressure on all edges.  

Reason 6: The glue is not functioning properly, perhaps because it is too old or lacking proper viscosity. Solution: Use a glue with a higher percentage of solids and recent date of production.

Adhesion strength is weak or has failed 
Reason 1: Usage date of the glue has expired. Solution: Check if the glue is old. 

Reason 2: Thinner is trapped. Solution: Extend drying time before pressing surfaces together. 

Reason 3: There is moisture on the glue. Solution: Check the working environment conditions and ensure that there is no excessive moisture or humidity in the air. Ideal working temperature is 22 degrees Celsius. 
Glue is leaking from one of the glued surfaces 
Reason 1: That surface was not clear of grease or moisture. Solution: Both surfaces must be clean and dry before contact glue is applied.

Reason 2: The glue has not yet dried. Solution: Extend drying time before bringing surfaces together. 
Contact Cements 
What is the recommended temperature for storing contact cement? 

To ensure that contact cement has a long shelf life, it should be stored at a room temperature of 22 degrees. The glue should not be left in situation of stagnation (i.e unused for years). 


What is viscosity? 

Viscosity is the degree of thickness or density of the glue. 
What are the precautions to take when using contact glue? 

If there is separation of solids and liquids in the glue container then these must be mixed together well before use. If the glue has frozen and turned into gel then it needs to be heated at 20 degrees Celsius before it can be used. Avoid the penetration of sawdust into the glue while it is being used. If the environmental temperature exceeds 25 degrees Centigrade, then this may decrease the drying time. By contrast, a longer drying time will result if there is humidity and moisture in the air, or if a thicker layer of glue has been applied.

What thinner can be used to clean any glue residues from the Formica surface after sticking?  

Avoid all thinners of lacquer because it can dissolve the dried glue, penetrate the seam line between the surfaces and destroy the adhesion. It is preferable to use kerosene. 

What should I look for in a convenient and spreadable contact cement? 

The best glue to use should contain a high amount of solids (to prevent over-absorption of the glue into wood). A medium viscosity will allow good spreading properties and coverage. The contact glue should also reach its full strength quickly for maximum effectiveness. 

How can air bubbles be removed after Formica has been stuck down? 

Assuming that there are sufficient amounts of glue below the surface, the area with the bobble needs to be heated with an electric heat source such as an infrared lamp. Then pressure must be applied with a roller, pushing the excess air to the edges and from there outwards. 
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