At Solimpeks, enamel quality is verified at every step, from the raw enamel slip to the fired coating inside each tank. Our in-house laboratory checks wet enamel for density, particle size and flow; tests fired enamel for citric-acid and boiling-water resistance, thickness, adhesion, thermal shock and suitability for drinking water; and monitors the rinse water used to prepare the steel. On top of that, every boiler and collector passes pneumatic and hydrostatic testing: 100 %, not a sample. In a solar water heater or storage tank, the enamel coating is the protective barrier between water and steel, which is why enamel testing is a foundation of our quality work.
Why does enamel quality matter in a hot water tank?
Enamel quality decides how well the steel of a tank is protected for its whole service life. Enamel is a glass-ceramic layer fused onto steel at high temperature, creating a hard, glass-like surface that resists corrosion, temperature changes and chemical attack — exactly the stresses a hot water tank faces through years of heating and cooling.
The coating does several jobs at once. It separates the steel from oxygen and dissolved salts in the water. Its smooth surface resists limescale and biofilm build-up, keeping the tank clean and efficient. And in an enamel-lined storage or buffer tank, it keeps the steel protected under continuous use across a wide range of water chemistries, working together with the magnesium anode. A coating with the right composition, thickness and adhesion is what gives a tank a long, trouble-free service life — and the only way to be sure of those properties is to measure them.
Where does the laboratory fit in our quality system?
The laboratory is one of four quality-control stages at Solimpeks: incoming material control, in-process control, final control and laboratory control. Its work covers three areas:
- chemical raw materials and the surface-preparation process;
- enamel raw materials and the coating process;
- the drying and firing thermal processes.
Our tanks are welded and enamelled on an automated welding and enamel coating line, and the laboratory's measurements are what keep that line's output consistent from batch to batch.
Which tests does our enamel lab run?
| Stage | Test | Standard / method | What it confirms | |---|---|---|---| | Process water | Conductivity, pH and concentration of rinse and wash-unit water | Routine process analysis | Steel surfaces are cleaned and rinsed correctly before enamelling | | Wet enamel | Density | Routine process analysis | The slip has the right solids content for an even layer | | Wet enamel | Particle size ("Bayer" test) | Routine process analysis | The enamel is milled to the correct fineness | | Wet enamel | Set value and flow time | Routine process analysis | The slip flows and settles consistently during application | | Fired enamel | Citric acid resistance | TS EN ISO 28706-1 | The surface resists acid attack | | Fired enamel | Boiling water resistance | TS EN ISO 28706-2 | The coating withstands long exposure to boiling water and vapour | | Fired enamel | Thickness | Coating thickness measurement | The layer is within the specified thickness range | | Fired enamel | Impact test (adhesion to steel) | TS EN 10209 | The enamel is firmly bonded to the steel substrate | | Fired enamel | Thermal shock resistance | Repeated thermal shocks | The coating stays intact through sudden temperature changes | | Fired enamel | Hygienic safety (migration analysis) | DIN EN 12873-1 | The coating is suitable for contact with drinking water | | Finished products | Pneumatic and hydrostatic tests | 100 % of boilers and collectors | Every unit is tight before it leaves the factory |
Why test the enamel before it is fired?
Testing the wet enamel catches deviations at the stage where they are quickest to correct. The slip's density, fineness and flow behaviour decide how evenly it covers the steel and how the fired layer will perform, so we check them before a single tank is coated. The rinse-water analyses do the same for surface preparation: correctly cleaned and rinsed steel is the starting point for good adhesion.
How do the fired-enamel tests reflect real service conditions?
Each fired-enamel test reproduces a stress the tank will meet in operation. The citric-acid and boiling-water tests expose the surface to chemical attack and prolonged hot water. The impact test checks that the enamel stays bonded to the steel under mechanical load. Thermal shock testing mimics sudden temperature swings, such as cold mains water entering a hot tank. Thickness measurement confirms that every area of the coating is within specification, and migration analysis confirms that the coating is safe in contact with drinking water. The 100 % pneumatic and hydrostatic tests then confirm the tightness of every finished boiler and collector.
Which product standards does this testing support?
The laboratory's work supports the standards our products are built and tested to: DIN EN 12897 for storage water heaters, DIN 4753-3 (UBA) for enamel protection on the water side, EN 12976-1 and -2 for factory-made solar systems, and DIN EN 12975 and ISO 9806 for solar collectors.
How does lab data drive continuous improvement?
Laboratory results feed directly into our continuous-improvement tools. We work with an APQP approach drawn from IATF 16949 practice, supported by FMEA, measurement system analysis (MSA), statistical process control (SPC), 8D problem solving and Kaizen. Customer feedback closes the loop: every complaint is recorded in our ERP system, and the root-cause analysis is shared with the customer within 14 days at most.
For us, the message is simple: an enamel coating is only as good as the testing behind it. Measured, standardised testing at every stage is what turns a thin ceramic layer into lasting protection for the tank and the water inside it.
