Gun foams or Straw foams?
When choosing between a gun foam and a straw foam, the most important thing to consider is the required quantity. For a small project using only a few cans of PU foam, it may not be economical to invest in a separate PU foam gun. For large projects, the higher yield of Gun foams may bring better value than using straw foams, even after taking into account the extra costs.
Note: you cannot use a PU foam gun on a straw foam, nor a straw applicator on a gun foam.
For a quick summary of the differences, check our table below.
|Gun Foams||Straw Foams|
|Other names||Gun-grade foams, Professional foams||Handheld foams, Manual foams|
|Application / Delivery||Uses a gun for application. This gun can be reused as long as it is taken care of properly, with a specialized PU foam cleaner. Guns and cleaners are separate costs.||Uses a straw for application. Each can of straw foam comes with a straw. No additional cost.|
|Ergonomics||The design of most PU foam guns allow for better ergonomics and easier dosing, especially when using large quantities. One-handed operation is much easier.||It is less ergonomic to extrude a can of foam using a straw, but it is usually not an issue for small quantities.|
|Yield||Gun foams have typically much higher yield, may be as much as 20% more than straw foams, dependant on brands, formulations, and quality of the gun.||Straw foams have high yield, but less than gun foams.|
|Density||Gun foams are of medium-low density (which allows it to attain higher yield). Note that density has effects on many properties, but generally lower density is considered better.||Straw foams are of medium density.|
|Cell structure||Gun foams typically have better cell structure due to the frothing effect of the PU foam gun.||Usually does not have a cell structure as fine as those on gun foams.|
|Expansion / Control||A user can have better control of the application of a gun foam, as foams are extruded in an expanded state. After extrusion, the foam usually expands 30 to 80%, so it is easier to estimate and dose the correct amount to fill a joint.||Straw foams are extruded in smaller beads, hence must expand more, between 70 to 150%. This makes it harder to estimate how much foam is needed to fill a joint.|
|Cost and Value||The unit cost of gun foams is usually more than straw foams. The cost of using Gun foams increases even more after taking into account cost of cleaners and guns. However, Gun foams generally provide better value once there is a substantial quantity, due to the higher yield of each can.||When used in small quantities, straw foams are cheaper and does not involve additional costs. However, lower yield means lower value in the long run for big projects requiring large amounts of foam.|
|Storage after use||After application, guns must be cleaned with cleaner, or left attached on the can with its screw control fully tightened. In this state, guns can last up to one month before it starts to cure inside.||Once a can is finished, the straw may be disposed together with the can. If a can is used halfway, straw foams cannot store properly, nor for too long.|
|Who it’s for||Professionals using large quantities and where application accuracy and cell structure is important.||Smaller users only using a few cans each time, with no technical requirement of density or cell structure.|