Today we made a special effort and conducted a test with an airless heated hose system. Heated hose systems in combination with airless devices are promoted with the following arguments: less overspray, less pressure used, better spray, more uniform surface, higher coverage and many other arguments.

But what are the real advantages of a heated hose in combination with an airless pump? To find out, we conducted a test. We sprayed a warm, clear paint on MDF panels and a wooden door. We also performed a pressure test to determine how much pressure could be reduced by the heating.

température tuyau chauffant

What is a heating hose?

A heated hose allows the varnish or paint to be heated. To do this, the conventional airless hose is replaced by the heating hose, which is mounted between the product outlet on the airless device and the airless gun.

Inside the heated hose is a heating wire that heats the paint as it flows. Most of the time, we work at a product temperature of 40 degrees, but many heated hose systems allow you to adjust the temperature as desired (for example, up to 60 degrees). The temperature is set via the control unit.

Steuereinheit des Wagner TempSPray H126

Wagner TempSpray H126 control unit

Advantages and disadvantages of an airless heating hose system

Before evaluating our test and its results, we should review the often touted advantages of heated hose systems, which will allow us to verify them directly in the test. In addition, we supplement the advantages with the disadvantages that result from the use of a heating hose.

Advantages of the heated hose

By using a heating hose system and heating the paint or varnish, it is possible to work with less pressure. The main advantage in this context is the reduction of the overspray, because less pressure always means less paint mist formation. There are also other side effects, such as the reduction of the load on the spraying device, gun and nozzle. This should reduce wear somewhat and increase service life. Better paint flow and coverage are also recurring arguments. In addition, the material can also be applied directly at colder temperatures.

    • reduced pressure
    • less stress on the spraying device (wear)
    • less overspray
    • faster drying
    • better spraying even at colder temperatures
    • better paint flow

Heizschlauch, spritzen mit weniger Druck

Heated hose, spraying with less pressure

Disadvantages of the heating hose

The advantages are of course counterbalanced by obvious disadvantages. These are mainly the costs of acquiring a heating pipe system as well as the expenses and costs of servicing, repair and maintenance.

    • Costs
    • More technology = more maintenance costs

Test – What is the interest of a heating hose?

Here we test the pressure and compare the possible pressure settings with and without heating. In addition, we spray the heated and cold material on MDF boards as well as on a profiled wooden door. In addition to the test design, we have collected information here about the spraying technique used as well as the coating used.

Pressure test with and without heating hose

To find out if the paint can be sprayed with less pressure with a heated hose system, we performed a pressure test. For this, the paint was sprayed without heating (about 11 degrees) at different pressure settings in the upper test series. We started at 60 bar, then increased in 20 bar increments to 180 bar.

This made it possible to determine exactly at which pressure setting a good spraying result could be achieved with the “cold” paint. The same test was carried out in the bottom row using the heating hose and heating the paint to 40 degrees.

Drucktest mit und ohne Heizschlauch

Pressure test with and without heating hose

Tests on MDF panels

To get an idea of the overspray formation, material flow and hiding power, drying and surface, we sprayed the heated and unheated material on a total of four MDF panels. The MDF panels were pre-primed in gray to better visualize the differences in hiding power.

On the first panel, the paint was applied cold from top to bottom. On the second panel, the paint was applied crosswise. On the third plate, the paint was applied from top to bottom, heated to 40 degrees. On the fourth plate, the paint was applied hot and crosswise.

Spritzen auf MDF Platten

Spraying on MDF panels

Profile Wood Door Test

In order to expand the test to real-world conditions, we didn’t want to spray only on smooth MDF panels. So we included a profiled door in the test. The door was previously sprayed with a gray primer, just like the MDF panels.

Then, we sprayed the door on one side with a non-heated varnish in a cross pattern. For the second side, the varnish was heated to 40 degrees and the application was also done crosswise.

Tür mit Airless & Heizschlauch lackiert

Airless painted door with heating hose

What spraying technique and coating did we use?

The result of a test is of course always dependent on the material used. Other materials can give very different results in terms of pressure setting, overspray and surface.

In addition, it should be noted that some paints are not suitable for airless application at room temperature.

Wagner SF 23 Plus mit H126 Heizschlauch

Wagner SF 23 Plus with Wagner H126 heating hose

In our test we used a Wagner SF 23 Plus pump equipped with the TempSpray heating hose. This means that a Wagner SF 23 Plus airless device was equipped with a Wagner H126 heating hose. The heating hose can of course be retrofitted.

The spraying was done with a purple Wagner FineFinish airless nozzle in size 410. The paint used is Airless Satin from Lucite. The product is ready to be sprayed and can be applied undiluted to a wet film thickness of 300 my.

Lucite AirlessSatin

“AirlessSatin” Lucite airless paint

Result of the heating hose test

In a print test, we heated the AirlessSatin paint to 40 degrees with a size 410 FineFinish nozzle and sprayed it cold at about 11 degrees. To do this, we applied the material to paper at 60, 80, 100, 120, 140, 160 and 180 bar.

In the upper row the material was cold sprayed, in the lower row it was heated. We were able to see that the coating spread well over the surface at a pressure of about 130 bar when the material was cold. By working with the heated material, the pressure could be reduced significantly, so that it was possible to spray at 90 bar. In the end, this meant a reduction in pressure of 40 bar. This is an advantage for the formation of paint mist and therefore also for the preparation and finishing work, as it saves time and material for masking and cleaning.

In addition, the paint consumption is reduced due to the reduction in misting.

Airless Drucktest mit und ohne Heizschlauch

Airless pressure test with and without heating hose

In a second step, we painted four MDF panels. During the preparation, we painted these panels in grey with a primer. The idea was to be able to better distinguish any differences in hiding power and color gradation on a gray background.

The first two panels were sprayed cold, at a material temperature of about 11 degrees. The first panel from top to bottom, the second crosswise. The paint used is quite forgiving, as it can be applied up to 300 my. Nevertheless, we wanted to test the cross pass and thus apply the material in greater thickness in order to get an idea of the coverage and to identify the risk of drips between the cold sprayed material and the hot sprayed material.

So for comparison, we sprayed the third and fourth plates hot. Once from top to bottom and once crosswise. We were able to see that the paint, AirlessSatin, sprays very well whether it is heated or not. The product is already set up for airless and can be applied directly without being diluted. Thus, even when cold spraying at 130 bar, there was very little paint mist. Visually, it was difficult to see a difference from spraying hot at 90 bar. Nevertheless, by reducing the pressure by 40 bar, we can expect a further reduction of the paint mist, even if it was not measurable with our means.

In terms of hiding power and paint distribution, we had the impression that the heated material spread differently and covered a little better. But we had to look carefully. When we checked after the surface dried, we didn’t see any more differences. Both cold and hot spraying resulted in a nice even surface. There were no runs or drips, either when applied overlapping or crosswise. Neither cold nor hot sprayed, so this paint is also suitable for beginners who don’t have much experience with airless application yet.

MDF Platten Airless mit und ohne Heizschlauch

Airless MDF panels with and without heating hose

Finally, we wanted to make the comparison on a profile door, a frequent and fairly typical application for the material. It is precisely in the corners and edges that paint can build up and form runs. The profiled surface also allows the test to be extended to more real-world conditions than the MDF panel. For this purpose, the first side was cold sprayed in cross mode, the second side of the door also in cross mode, but with paint heated to 40 degrees.

The results of the previous tests were confirmed here. No dripping or dripping despite the surface profiling. Cold spraying at 130 bar resulted in a nice even spray pattern and a homogeneous surface. The same applies to spraying with heated paint at 40 degrees and 90 bar pressure. Subsequent observation after the surfaces had dried also gave a satisfactory result.

Tür im Kreuzgang spritzen

Spraying of the door and the folds

Conclusions of our tests of the heated hose

The test showed that Lucite AirlessSatin sprays very well with or without heat. It is possible to achieve a nice spray with both heated and cold product. The product spreads well over the surface and covers both hot and cold. When cold, we were able to spray the paint in our conditions with a pressure setting of 130 bar. With heated material, it was possible to reduce the pressure from 40 bar to 90 instead of 130 bar. This results in a number of advantages when using the heated hose system in the area of paint mist formation, paint consumption as well as the effort required for masking and preparation and finishing work for cleaning.

In addition, the product consumption should be somewhat lower and the sprayer is less stressed. The test also showed that when spraying with heated material in a wet state, the paint seems to cover the surface slightly better. This advantage is no longer visible after drying. It would therefore make sense to extend the test to other paints. Another advantage of the heated hose system is during the cold season, because the paint is heated in a short time, so that the working conditions are always the same. This means that the material is immediately ready for spraying, even if it has just come off the truck and the temperature is only 5 degrees.

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