# Evaluation of Marblewood Dust's (_Marmaroxylon racemosum_ Effect on Ignition Risk
## 2 Materials and Methods  
MW dust samples were prepared from raw material, marblewood (_Marmaroxylon racemosum_) with a density of 1000.08 \(\pm\) 9.98 kgm\({}^{-3}\). The basic samples with dimensions of 120 \(\times\) 35 \(\times\) 35 mm\({}^{3}\) and a moisture content of approximately 8-10% were made in a private company that manufactures interior elements based in Zilina (Slovakia) using a wood cutting saw (CNC Panel Saw Machine, Shandong, China) (Figure 1).  
Figure 1: Experimental dust samples.  
The dust samples (Figure 1) were sanded using a Makita 9556 CR 1400W disc sander (Makita Numazu Corp., Branesti Ilfov, Romania) and K36 sandpaper (Topex, Kinekus, Zilina, Slovakia). A detailed description of the procedure is given in [31].  
The moisture value of the tropical wood samples was determined using granulometric analysis according to [32]. The bulk density of wood dusts was determined according to [33]. Sieve analysis was conducted on a Retsch AS 200 sieve shaker vibration machine (Retsch AS 200 control, Retsch GmbH, Haan, Germany) in line with [34].  
The microscopic analysis was realized using a Nikon Eclipse Ni (Nikon Corp., Tokyo, Japan) with a Nikon DS-Fi2 camera (Nikon Instruments Inc., Melville, NY, USA) for the determination of the shape and the size of marblewood dust particles. The microscopic analysis (for 500, 315, 200, and 100 \(\upmu\)m fractions) was completed at the Institute of Research in Banska Bystrica, Slovakia. The determination of the particle size was limited by the technical specifications of the cameras. The scans of fraction sizes \(<\)63, 63, and 71 \(\upmu\)m were unreadable. A detailed description is given in [35].  
The measures of the minimum ignition temperature of airborne dusts (Figure 2a) were conducted in a test equipment (VVUU, a.s., Ostrava, Czech Republic) with the help of the following accessories: automatic weighing machines (Steinberg Systems, Lodz, Poland), HL 100 ZU EINHELL air compressor (Einhell Corp., Landau an der Isar, Germany) and ALMEMO equipment (Ahlborn, Berlin, Germany) (Figure 2a). The procedure was conducted in line with [36] and details are described in [35]. The minimum temperature of airborne dusts was tested in 10 experiments with constant volumes of marblewood dust and different air flows.  
The minimum ignition temperature of a dust layer (thickness 5 mm) was determined on an electrically heated plate, 185 mm in diameter, according to [36] (Figure 2b). This standard defines the minimum temperature for ignition of a dust layer as the minimum temperature of a hot surface at which ignition can occur of a dust layer with a set thickness located on that hot surface [37]. The experiments were performed on a laboratory hot plate apparatus with temperature controller, type CLARE 4.0, with measurement errors of \(\pm\)0.3 \({}^{\circ}\)C (Clasic, Czech Republic) in the experimental laboratory at the Faculty of Safety Engineering in Zilina (Slovakia). Detailed information about the behavior test is available in [38,39].  
Figure 2: (**a**) The test equipment for the measurement of the minimum ignition temperature of airborne dusts; (**b**) experimental equipment “hot-plate” from [39].