Varnish Systems Research Articles

The Impact Of Ultrasound-Assisted Mixing Method For Varnish And Components On The Varnish Layer’s Surface Hardness And Surface Scratch Resistance

The objective of this study was to determine effects of mechanical and ultrasound-assisted stirring methods for varnish + components mixing on the varnish layer’s surface hardness and surface scratch resistance. The study focused on polyurethane, acrylic, and polyester varnish systems, which were applied to three distinct wood types: Scots pine (Pinus sylvestris L.), Turkish beech (Fagus orientalis Lipsky), and African mahogany (Khaya ivorensis A. Chev.). The mixing processes included mechanical stirring for 3 and 5 minutes, as well as ultrasound-assisted stirring with varying power levels (80 watts and 120 watts) for 3 and 5 minutes. The results indicated that the highest surface hardness was achieved using the mechanical stirring method for Turkish beech with polyester varnish at 3 minutes of stirring (175.10), while the lowest surface hardness was observed for African mahogany with acrylic varnish and 120 watts ultrasound-assisted stirring for 5 minutes (66.80). The highest surface scratch resistance was observed in Scots pine treated with polyester varnish using mechanical stirring for 5 minutes (0.760 N), and in Turkish beech treated with acrylic varnish using 80 watts ultrasound-assisted stirring for 3 minutes (0.760 N). Overall, the findings suggested that the ultrasound-assisted mixing method generally fell short in terms of enhancing the varnish properties compared to the mechanical mixing technique.

Effect of adhesion promoters on rheokinetics and roll peel strength of electrical steel stacks

Epoxy varnishes for stacked electrical steel are of high relevance for renewable energy and electric mobility technologies. Water-borne epoxy varnish systems are still under development, especially with regards to the improvement of the adherence to the steel substrate. The main objective of this study was to assess the potential of low molar mass, silane-based adhesion promoters (AP) with amine or glycidyl functional groups as to their effect on the crosslinking kinetics of coatings and the mechanical performance of electrical steel laminates.Model formulations with different types and contents of silane AP or in combination with a pre-crosslinker were based on a Bisphenol A diglycidyl ether, a dicyandiamide (DICY) crosslinking agent and an emulsifier. The amount of water was fixed to 45 m%. Model varnishes were prepared by shear emulsification at elevated temperatures. Varnishes were applied onto electrical steel sheets and partly crosslinked to the B-stage. Finally, coated steel sheets were stacked and laminated in a heated press.To examine the crosslinking kinetics under non-isothermal conditions, rheokinetic measurements were performed. While the curing onset temperature of formulations with amine-based AP dropped by ∼10 °C, the effect of the epoxysilane AP was less pronounced (drop by ∼5 °C). Pre-conditioning of the varnishes in A-stage revealed a further reduction of the curing onset temperature associated with significantly higher initial viscosity. This was a clear indication for pronounced pre-crosslinking in A-stage and hence, a limited shelf life of silane-modified varnishes. The glass transition range in the fully cured state was solely affected by the diamine-based AP. Interestingly, the investigated low molar mass silane APs had no significant positive effect on the roll peel strength of the laminates.

Effects of Ultrasound-Assisted Varnish and Component Mixing Method on Mechanical and Physical Properties of Varnish Layer

The aim of this study was to determine the effects of mechanical and ultrasound-assisted stirring methods for varnish + components mixing on the varnish layer coating adhesion, surface roughness and glossiness. For this purpose, polyurethane, acrylic and polyester varnish systems were applied on three different wood types, namely Scots pine (Pinus sylvestris L.), Eastern beech (Fagus orientalis L.) and Mahogany (Khaya ivorensis), with mechanical and ultrasound-assisted mixing methods. In the mechanical mixing method, 3 and 5 minutes were applied, while in the ultrasonic mixing method, beside 3- and 5- minute stirring time, 80-watt, and 120-watt ultrasonic power was applied during mixing. When research results are generally evaluated, it cannot be said that ultrasound-assisted mixing method is superior to mechanical mixing method. However, the ultrasound-assisted mixing of varnish components at 80 watts for 3 minutes can be recommended.

Evaluation of Eco-Friendly Nanomaterial Modified Water-Based Varnish Systems

Evaluation of Eco-Friendly Nanomaterial Modified Water-Based Varnish Systems

Gloss of Varnished MDF Panels Veneered with Sanded and Thermally Compressed Veneer

The objective of this study was to investigate the gloss of different types of commercially manufactured varnish systems, including water-based (WB), polyurethane (PUR) and UV-cured (UV), applied on veneered MDF panels with sanded and thermally densified alder and birch wood veneers. The varnishes were applied at various numbers of layers on veneered panels. The gloss was measured at three angles of incident light: 20°, 60° and 85°. Statistical analysis showed that the type of varnish, the number of layers, the pre-treatment process, the wood species and direction of wood fibers significantly affect gloss of the coatings of veneered MDF panels. The type of varnish had a dominant effect on gloss. The highest gloss values were measured for the UV-varnished surface, and the lowest for WB- and PUR-varnished surfaces. Gloss was enhanced with an increase in the number of layers. Birch veneer provided higher gloss values compared to alder veneer. The gloss values measured along the wood fibers were higher than those measured across the fibers. No significant differences were found between the coatings created on sanded and thermally densified veneers for the average gloss values measured along the fibers at angles 60° and 85°. This study could have practical applications for producing value-added furniture elements using low-value wood species pre-treated by thermal compression.

The Impact of Sanding and Thermal Compression of Wood, Varnish Type and Artificial Aging in Indoor Conditions on the Varnished Surface Color

The aim of this pioneering study was to compare and evaluate two different pre-treatment processes of wooden surfaces prior to varnishing by sanding or thermal compression in terms of the impact on the color characteristics of the varnished surface. In the experiment, a wood veneer of black alder and birch before varnishing was subjected to sanding with a sandpaper of 180 grit size, or thermal compression at temperatures of 180 and 210 °C. Three different kinds of commercially manufactured transparent varnish (water-based (WB) varnish, polyurethane (PUR) varnish and UV-cured (UV) varnish) were applied to the prepared veneer surfaces. The samples prepared in this way were also subjected to an artificial aging process in indoor conditions by ultraviolet light and infrared irradiation (UVL + IR). The colors of the surfaces in the CIE L*a*b* system were measured and color differences (ΔL*, Δa*, Δb* and ΔE) were determined for sanded and thermally densified, unvarnished and varnished, as well as subjected to accelerated aging surfaces. It was found that thermally densified surface-varnished veneer is more resistant to color changes during artificial aging compared to when sanded and surface-varnished. The transparent varnish systems showed better photo-stability, when thermally densified wood veneer was used as substrate than that of sanded wood. The WB varnish showed the greatest resistance to discoloration during UVL + IR irradiation, followed by PUR and UV. The preliminary findings obtained in this study indicated that replacing the sanding process with thermal compression of wood surface before varnishing could be considered as an alternative method of producing varnished panels with satisfactory color properties of surface.

СИСТЕМА ЛАКОКРАСОЧНЫХ ПОКРЫТИЙ НА ОСНОВЕ ПОЛИУРЕТАНОВОЙ ЭМАЛИ ДЛЯ ЗАЩИТЫ ЛОБОВЫХ ОБОГРЕВАЕМЫХ ПОВЕРХНОСТЕЙ ИЗДЕЛИЙ АВИАЦИОННОЙ ТЕХНИКИ

The paper presents the results of studies of paint coatings system based on natural drying polyurethane enamel in the initial state and after accelerated climatic tests. It has been determined that the use of an epoxy-rubber primer provides the coating with high resistance to erosion wear, both in the initial state and after various aging factors, as well as a high level of protection against corrosion of the aluminum alloy. It has been defined that exposure to elevated temperatures has a positive effect on the erosion resistance of paint and varnish systems.

The influence of multi-layered varnishes on moisture protection and vibrational properties of violin wood

Violin varnishes are known to affect both moisture absorption and vibrational properties of violin wood. However, traditional multi-layered varnish systems suffer from substantial wear as a result of intensive use, which calls for deeper understanding of the specific impact of individual layers. Using sophisticated in-situ neutron imaging and vibrational modal analysis, we show how wood sorption and vibrational behavior of tonewood depend on the build-up of the varnish system. The results demonstrate the protective effect of complete coatings and emphasize that strongly worn regions cannot accomplish the function as an effective moisture barrier, which might pose a risk for frequently played or aged string instruments. Furthermore, the build-up of the varnish system affects the vibrational properties of the tonewood, influencing its final sound quality. This delicate interplay should be considered both for the handling of antique and aged violins and for the production of modern high-quality instruments.

Adhesion properties of some protective layers exposed to outside weather conditions for five years

In this study, the long-term (5-year) performances of 2 varnish systems, semitransparent alkyd-based brown stain (SABBS) and alkyd-based clear varnish (ABCV), were evaluated on preservative-treated Scots pine (Pinus sylvestris L.) sapwood. Prior to varnish application, specimens were impregnated with 2 different types of wood preservative. The experimental variables were varnish type, layer thickness, and wood preservative. ASTM D 1641 was followed for exposing wood specimens to outdoor conditions. The effects of long-term exposure on adhesion properties of applied varnish systems were tested according to ASTM D 4541. Long-term outdoor exposure resulted in 4.2% and 33.9% reductions in the adhesion properties of SABBS and ABCV varnish systems, respectively. The layer thickness and preservative type did not show any statistical reductions in adhesion properties.

Comparison of Conventional Varnishes with Nanolacke UV Varnish With Respect to Hardness and Adhesion Durability

The long-term durability of varnished wooden surfaces used in either indoors or outdoors environments depends on the resistance of varnish layers on these surfaces against potential physical, mechanical and chemical effects to which they may be exposed. In this study, "Nanolacke ultraviolet varnish", developed by a Turkish dying and varnish industry company and widely accepted as a 21(st) century technology has been compared to other conventional varnish systems widely used in the industry in terms of dry film resistance properties. In this study, cellulosic, polyurethane, polyester, synthetic and Nanolacke ultraviolet varnish have been applied on beech (Fagus orientalis L.) and oak (Quercus robur L.) wood samples which had been prepared according to the industry standards. Then, the hardness and adhesion resistance of these layers have been determined according to ASTM D 4366 and ASTM D 3359-2 standards, respectively.

Waterborne acrylic varnishes durability on wood surfaces for exterior exposure

The protection performance of varnishes applied to two different wooden substrates (maritime pine and iroko) for outdoor exposure was investigated for eight different varnish systems (with and without colorants and two different light stabilizers). All were subjected to accelerated artificial weathering and natural weathering. Several test methods were used to evaluate the appearance and physical–chemical properties of the coatings during the degradation. The results obtained lead to the selection of the best varnish formulation for the protection of wood for exterior use and provide useful evaluation of the test methods employed.

Short‐term anti‐plaque effect of two chlorhexidine varnishes

Chlorhexidine (CHX) varnishes have been mainly used for the prevention of caries in high-risk populations. Reports regarding their anti-plaque effect on a clinical level are limited to non-existing as opposed to their microbiological impact on plaque formation. The aim of this preliminary investigation was to evaluate the anti-plaque effect of two CHX varnishes applied on sound enamel in relation to a positive control, a negative control and to one another. Sixteen healthy subjects volunteered for this randomized-controlled, single-blind, four-treatment-four-period crossover-designed clinical trial. A 3-day plaque re-growth model was used to determine de novo plaque accumulation following CHX rinsing, Cervitec application, EC40 application and no therapy. The amount of plaque was measured using the Quigley and Hein plaque index and "automatic image analysis" (AIA). Varnish treatment resulted in significantly higher plaque levels than CHX rinsing irrespective of the varnish that was used (p< or =0.002), implying that the latter is likely to remain the gold standard as an anti-plaque agent. However, highly significant differences were also found in favour of both varnish systems when compared with no therapy (p<0.001), which indicates that varnish treatment is an effective means of inhibiting plaque formation in a short time span. Cervitec exhibited slightly, yet significantly, higher plaque levels in comparison with EC40 as determined by AIA (p=0.006). Large-scale trials with a longer observation period are necessary to substantiate these results.

Indoor Emissions from Conversion Varnishes

ABSTRACT Conversion varnishes are two-component, acid-catalyzed varnishes that are commonly used to finish cabinets. They are valued for their water and stain resistance, as well as their appearance. They have been found, however, to contribute to indoor emissions of organic compounds. For this project, three commercially available conversion varnish systems were selected. A U.S. Environmental Protection Agency (EPA) Method 24 analysis was performed to determine total volatile content, and a sodium sulfite titration method was used to determine uncombined (free) formaldehyde content of the varnish components. The resin component was also analyzed by gas chromatography/mass spectroscopy (GC/MS) (EPA Method 311 with an MS detector) to identify individual organic compounds. Dynamic small chamber tests were then performed to identify and quantify emissions following application to coupons of typical kitchen cabinet wood substrates, during both curing and aging. Because conversion varnishes cure by chemical reaction, the compounds emitted during curing and aging are not necessarily the same as those in the formulation. Results of small chamber tests showed that the amount of formaldehyde emitted from these coatings was 2.3–8.1 times the amount of free formaldehyde applied in the coatings. A long-term test showed a formaldehyde emission rate of 0.17 mg/m2/hr after 115 days.

Conical bead mill improves the grinding process

In the printing ink industry, the trend increasingly points towards the application of special varnish systems and pigments for packaging and decorative inks. As a consequence, there is an increasing demand for equipment capable of coping with this difficult dispersion process. Buhler has accepted this challenge, launching a bead mill provided with a conical gap agitator and a dynamic separation gap relief system.

Heat-resistant insulation systems for motors

The thermal stability of a new magnet wire known as Alkanex? wire has been evaluated as a component of heat-resistant motor insulation by four different test methods. Alkanex wire has been shown to possess approximately a 40 degrees centigrade (C) superiority in thermal stability as compared to Formex ® wire when used with suitable varnish systems. It is important to choose varnish and solvent systems which are compatible with the wire enamel. It is concluded by test that Alkanex wire can be used in equipment operating at class B temperature and that use need not await confirmation by long service trials.