Spray polyurea coatings has been widely used on wood speakers, to make it better waterproofing, anti-impacting and anti-abrasion, the polyurea for speakers is fast cure, more rigid than waterproofing polyurea, so it can get a special granular texture, and good scratch resistant property.

But how to apply polyurea on wood speaker box? this article will give you some advice.

1. Preparation of the wooden case

Surface preparation is very important for spraying polyurea, because polyurea cured very fast, if there are pinholes on the surface, we will get defects, and be honest, it's much difficult to repair the defects on polyurea than on the substrate before spraying polyurea.

So that we should prepare the wood box carefully before spray polyurea.

1) Because the polyurea coating and the polyurea primer have poor adhesion with water-based putty, solvent-based putty, poly-putty, so that we cannot repair the wood case with above putty in a large area; therefore, it can just be partly repaired for nail hole, small pit, the corner of the wood on the surface of the case, beware that the repair area should be as small as possible.

2)After the putty cured, use the fine sandpaper polish the repaired area on the surface of the wooden case, to ensure that the surface and repaired area of the wooden boxes are smooth, without any defect. Clean the surface of the wooden case with an air gun.

3)Carry the box carefully before spraying, at the same time, it is necessary that there should be no dust and hard objects on the surface of the bracket where the wooden case was placed in order to prevent the secondary damage on the wooden case during handling and storage.

2. Details of spraying

1)Check the spray machine and raw material and get them ready, due to the corner of the speaker box are easy to be impacted, and to prevent spraying leakage, we suggest spraying the corner and the area where was hard to handle first, and then spraying the rest large area of the wooden case.

2)Thickness requirements: the thickness of polyurea coating at the corners where is easy to be damaged should be equal or greater than 0.8mm and the thickness of the plane surface should be equal or greater than 0.6mm.

3)If there are some soft tiny particles on the surface of the polyurea coating after sprayed, you can use the blade to remove them gently from the top of the particles, be careful and not to touch other area.

4)When stippling on the surface of the wooden box, it is not allowed to spray continuously or without shaking, Otherwise, stipple on the surface of the wooden box will be flat and shiny, which cannot achieve a good mat granular surface, so you should quickly discontinuously switch the trigger and shake the spray gun while spraying stipple.

5) The interval time between the two layers of polyurea coating should not be too long. The interval time should be with in 1.5 hours. If exceed 1.5 hours, the surface of polyurea must be polished rough, and then spray polyurea, in order to get better adhesion.

6)Coating repair: if there is defects on the surface of polyurea coatings and need to repair, must be polished the repair area, and then spray polyurea.

3. About the adhesion of polyurea coatings on speakers

We usually spray polyurea on speaker box without primer. The adhesion of polyurea on different kinds of wood was different; the adhesion on the MDF is poor; the adhesion of plywood is better; the adhesion of birch is the best, due to the manufacturer is different, the adhesion of the same material is a little bit different.

For example, the adhesion of polyurea to Russian birch is better than that to Chinese birch. If the adhesion fails to meet the requirements of your company, please use the special primer for speakers of Qingdao Polyswell Technology.,Ltd.

1) Ensuring the wooden cases are prepared well, the primer can be sprayed on the surface of the wooden case, and the primer shall be applied evenly on the surface of the wooden case and as thin as possible.

2) If the primer is too thick, there will be bubble and poor adhesion on the surface after spraying polyurea coatings.

3) If applied primer on wood case, be sure that the primer is dried before spray polyurea.

4. Requirements for equipment

1) set the temperature of main and hose heater at 65-70 ℃ (150-160 ℉).

2) set the equipment outlet pressure on 2000-2500psi.

3) set the equipment outlet pressure deviation in 0-400psi.

4) Ensure A, B material pump work normally.

5. Other requirements

1) When the environment temperature is less than 15℃, material A and B need to be heated with a heating belt, to reduce viscosity of material A and B

2) When the environment temperature is less than 15℃, the strength of polyurea coating increases very slowly, polyurea coating is crispy after spray, which needs to be carried carefully. It’s better to move the sprayed boxes in 35 ℃ in the drying room for 5 hours, or under 25℃ for 24 hours to get better strength.

There are many details when spray polyurea on speakers, and different chamber and tips of the gun, with different spray skills will get different granular texture, as a professional polyurea manufacture especially in speaker box field, we have rich experience, if you have any further question pls feel free to contact us.