Up to now your customers mainly came from the automotive industry, for which you developed a cylinder head gasket; but for more than two years now an entirely different industry has joined your customer list - baked goods manufacturers. How did that come about?
The starting point was that an oven manufacturer approached us who was having problems with the non-stick effect of baking trays and grill plates. That was three years ago. At that time, robustness, durability and temperature resistance were the calling card of our DURAPEK® coatings. In terms of non-stick performance, we were a bit behind the best. In exchange, our product lasted longer. Prompted by that inquiry, we looked intensively into the non-stick effect and advanced it significantly. We caught up, then overtook. The nice thing is that we now achieve good to very good non-stick performance for everything at once with a single coating - for sweet goods, for alkali treatment, for fish, for meat.
What's requested most often?
The sweet side, e.g. for baked goods with a high sugar content or sticky, fruity fillings. Independent of that, we initially focused on alkali trays. We solved the alkali problem. Everything else currently seems simpler to me.
What does that mean?
We developed a new alkali tray. It's not yet a revolution, but the tray looks different. It's a bit thicker, more precise, 2 mm thick, and made of aluminum that's folded on all four sides. That makes it very stable. And very important: it's not hemmed. Because if alkali gets into a hemmed seam, it comes into contact with aluminum. Aluminum gets dissolved out and could come into contact with the baked good. That's why we decided to coat the tray all the way around. Nothing may remain open. Since there's no seam, we had to come up with a special solution for the coating process. We developed matching stainless steel rivets that are applied to the tray, and we hang the tray from them for coating. Now your "but" should come…
… the gap between the stainless steel rivet and the aluminum could be a weak point.
You might think so. But it isn't. The aluminum tray with the stainless steel rivets is coated and then run through the oven. The gap gets densely coated. So the rivet doesn't just hold mechanically - it's also effectively welded.
Are there application tests?
A baker in southern Germany is testing our trays. When he first saw our product, he said: "I know rivets, they're broken after three months." We said: "Then try it." And the rivets hold. The tray has been in trials for several months now and is running flawlessly. In parallel, we had it tested by TÜV. TÜV completely submerged the trays, rivets included, in the alkali solution, and no aluminum was washed out.
Among others, BÄKO also presented an alkali tray at südback - made of stainless steel.
We'll see which solution is preferred. Other companies also offer stainless steel trays for alkali applications. In one case I find good, with relatively large hexagonal, honeycomb-like cutouts. Since the cutouts are large enough, stainless steel's disadvantage - its poor heat conduction - is somewhat compensated for. Our alkali tray, though, has the advantage of being lightweight, having the baking properties of aluminum, and still being safe against alkali. In the end it's naturally also cheaper than stainless steel.
Was the coating modified for alkali baked goods?
The coating was modified for baking applications in general, not specifically for alkali. That wasn't necessary. We could of course choose a different color for every application. But we think that would be nonsense.
But can you coat in a custom color on customer request?
Of course. Though black alone is already the best choice in terms of heat absorption.
Let's come back to the coating process. What's different about it?
We follow a different chemical approach. Our coatings are completely solvent-free. There are also no substances that could off-gas or decompose when heated. Additionally, the layer thicknesses are higher, in the range of 60 to 70 µm. So they're twice as thick as usual.
How does the coating process work?
While PTFE non-stick coatings ("Teflon") are applied wet with solvents onto trays and molds, we use powder that's applied dry in several electrostatic layers and then baked. That's why we can work without solvent residues or oils. Coating happens right here on site in Wilhelmshaven, automated across two fully automatic continuous-flow lines. The best coatings are four layers; the simple ones, three.
Are the processes reproducible?
Yes. Every product coated by us once receives a processing number, under which all parameters are stored in the line control system - oven temperature, run time, the speed at which the product moves through the booths, the layer thickness for inspection, etc. For an order, only the correct program number needs to be selected, then the rest happens automatically. The program numbers are stored customer- and product-specifically in the ERP system. We're certified for the automotive industry and have already delivered millions of parts. Nothing can go wrong there, and it doesn't.
Could you specify the term "powder"?
By powder I mean our coating compounds, which have a consistency like powder, comparable to flour. They consist mainly of the high-performance plastics PAEK (polyaryletherketone). We buy the raw polymers from chemical companies and manufacture the coatings exclusively ourselves. For that we use a special facility that only we have. So we work completely independently. Our coatings are multiply patented.
That doesn't actually sound complicated…
That's deceptive. A coating consists of 20 different substances. There's enormous development effort involved in finding the right mix for an optimal result. It's Sisyphean work. We've been working on our non-stick coatings for around 15 years; the beginnings of PAEK coatings go back over 20 years, back then for cylinder head gaskets. It seems to have become unfashionable to work on the same thing for a long time, but if you do, you have the advantage of being a step ahead of others.
"It seems to have become unfashionable to work on the same thing for a long time, but if you do, you have the advantage of being a step ahead of others."
Dr. Christoph Stecher, Managing Director, acs Coating Systems
Why PAEK?
We wanted thermoplastics, because they have the property of becoming liquid at a certain temperature. That means the oven is enough, instead of working with solvents that are often even carcinogenic. In addition, wear properties and long-term durability are very good. There's no embrittlement. We use PAEK because these high-performance plastics are chemically very resistant and hard at the same time. Even at high temperatures nothing off-gasses, which we've also had tested. Small catch: they're more expensive and not as easy to process. But dealing with that has been our business for 20 years. Because the raw materials are already in the upper price segment, we obviously can't produce cheap, low-price coatings. But if you calculate all the way through, you'll see that our baking trays ultimately save money.
You'd have to explain that.
For one thing, our trays have a longer lifespan. The coating lasts longer. For another, bakeries save energy and baking time, and don't need baking paper either. More time means more units per unit of time, lower personnel costs, and so on. We put together an example calculation from the perspective of a baker with about 1 million euros in annual revenue. It showed that the extra cost of DURAPEK® baking trays pays for itself within three months. From then on, they save money - because less energy is used, because a lower oven temperature is needed, because baking time is saved, because no baking paper is needed. So the seemingly more expensive product is actually the cheaper and more sustainable one. Retailers are increasingly demanding sustainability.
What savings in time and temperature are possible?
Our customers report time savings of 10%. They were able to reduce the temperature by 10 to 20 °C to achieve the same baking result.
Is there a guarantee for how long the trays last?
I can't give one yet, since the applications vary so much. But I do have an example. A customer required 20,000 baking cycles. As of today, cycle 177,000 has been reached.
Can DURAPEK® baking trays be recoated?
In principle, yes. It's just that, because the coating is expensive relative to the metal, and removing the coating is logically very labor-intensive, it doesn't pay off. I assume the trays will last a very, very long time and will have paid for themselves well.
According to some tray manufacturers, wear on aluminum trays mainly results from pushing them in and out of trolleys or the rails of an in-store oven. Do you see a problem here?
With us, this area is always coated, even on simple baking trays. And the coating is basically the same as on a BMW exhaust flange. That has to last ten years and withstand temperatures up to 300 °C, with parts sliding against each other. Or like the cylinder head gasket, which also has to last ten years and endure difficult thermal movement under heavy load. Our grill plates for catering are also pushed into the oven and last practically forever. With a smooth sliding surface and appropriate use, I don't see a problem.
Do baking trays make up your main business?
So far, yes. I could imagine our bread baking bands and cake molds at least catching up. The bread pan sets have been tested by a baker for a year now. "They fall out without release agent," he says. We can also coat the bread baking bands well automatically.
What are your goals?
We want to be ten times as big in 10 years as we are now. We can manage that. After all, we're starting essentially from nothing. We've already achieved a lot toward that.
How do you bring together your five pillars - automotive industry, baking industry, catering, houseware and industrial coatings - under one roof?
The industries are completely different, as are the applications. But the solution approaches are similar. There are different coating compositions and different programs, but the machine equipment and workflows are the same.
Dr. Stecher, thank you very much for the conversation.