Bubbles in the outside wet lacquer after curing

Correctives 1 – Too much heat during the first part of the curing process:

1.1.  The tin flow has to to be only as wide as the width of the powder and / or lacquer stripe and not more (usually around 15 mm for food and aerosol cans)!
- This width covers also lateral shifting can bodies during daily production!
- The internal powder must have a low melting point, starting from about 180°C!
- Most commercially available and good powder coats are fulfilling this demand For further information for recommended powders, please contact Can Man.

1.2.  The conveyor speed in the oven is too high, therefore the curing time too short!

– Distances between the cans of more than 1/2 canbody height is a reduction in curing time of 25% (or from 5 sec. to only about 3,8 sec.!)

1.3.  The adjustment of the coil to the can bodies is wrong.

1.4.  The curing length is too short (before order a longer curing system, please follow first the Correctives 2 and 3!)

Corrective 2 – The wet lacquer application is not constant, too thick or too thin!

2.1.  Especially for induction curing system, with shorter curing time, a constant film thickness is required!

- Please note that a constant and a “as thin as possible” lacquer application is essential not only onthe curing effect, but it also reduces the lacquer cost!

2.2.  The can body must be round – within standard tolerance -, overlap begin and end must be equal!

2.3.  Depending on the configuration, rubber roller or steel rollers must be used!

- For further information and / or support contact Can Man.

2.4.  The speed of the application roller is wrong, compared to the passing can bodies!

- Generally can be said, that a too high application roll speed leads to worse results than a too slow one.

- Depending on steel or rubber rollers different speed than can body speed might be used, but must be controlled and monitored.

2.5.  The material and / or the form of the rubber/steel roller profile is wrong!

- For the use of a steel roll (longer lifetime) we urgently recommend to have a “supporting conveyor “under” can body (available at Can Man)

Corrective 3 – Wrong wet lacquer type in use:

3.1.  Not every wet lacquer type is applicable for induction curing system due to the fact that the heat up ramps are much faster than with a gas curing system

- For a list of recommended (and pricewise competitive!) lacquers contact Can Man

3.2.  The correct viscosity and therefore the proportion of solvent is most important for a non-porous side seam protection.

- For further information and / or support contact Can Man.