Wet Paint Research Articles

Wet Paint: Visual Culture in a Changing Britain – A Round Table Debate

Political decisions and debates regarding the interregional and international partnerships that constitute Great Britain, including those over Scottish Independence, EVEL (English Votes for English...

Drying and Consolidation in Drying Colloidal Dispersions

When a thin film of wet paint or coating containing suspended submicron sized colloidal particles is dried on a substrate, evapora- tion of the solvent concentrates the particles. The drying and consolidation process leads to the formation of space filling particle networks and in many cases gives rise to tensile stresses in the network. Drying and consolidation process builds up stresses in the colloidal packing while packing flaws such as voids and dislocations nucleate cracks thereby compromising the mechanical integrity of such materials. An understanding of the fluid-solid phase transition for varying particle size, shape and chemistry (inter-particle interaction), followed by prediction of particle packing as a function of the said parameters in the presence of exter- nal fields is critical to industries as diverse as electronics, paints, coatings, ceramics, and agriculture. The paper presents some of our recent work on the film formation and cracking phenomenon in wet films formed from colloidal dispersions.

Giverny

Giverny Callie Siskel (bio) “Nature never stops”—Claude Monet There’s nothing in the garden as yellow as the dining room. Nothing as opaque. A single buttery shade covers the walls and closes around the furniture. Two lengths of rope tie the room off from the house as though warning of wet paint. It’s lacquer and sunlight through the patio doors that give the illusion of liquid where there’s none, where everything is set. Even the yellow table, draped in white and the eight cane-back chairs, each one pushed in to a willowware plate and a crystal glass we couldn’t raise. You were my father for nearly thirteen years. I asked you why [End Page 42] we weren’t allowed to touch anything that day, but you could not have known the room would go unchanged, and we would be outlasted by a heavy coat of paint. [End Page 43] Callie Siskel Callie Siskel teaches in the Writing Seminars at Johns Hopkins University. Her poems appear or are forthcoming in The New Criterion, Able Muse, Passages North, and Tar River Poetry. Copyright © 2014 Johns Hopkins University Press

Compatibility of photocatalytic TiO2-based finishing for renders in architectural restoration: A preliminary study

Self-cleaning finishing treatments based on the use of TiO2 nanoparticles have been recently proposed for the protection of materials in cultural heritage, with the aim of increasing the durability of these materials in polluted environments. The results on stone seem encouraging, but the experimental tests on different porous materials, such as bricks and renders used in historical buildings, are still extremely limited.In the present paper, the application of water dispersion of titania nanoparticles to the repair renders of the former Del Corso hotel (XVIII cent., Bologna, Italy) was evaluated. The building and its environment were first analysed for assessing the appropriateness of such finishing, then samples of painted renders identical to those provided for in the intervention work were manufactured and treated with the dispersion, both by brushing on the dry paint and by brushing on the wet paint (the latter procedure in order to enhance the particles retention by exploiting the mechanism of fresco paintings). The outcome of the different treatments was investigated mainly to evaluate its compatibility with the substrate and its durability, which could be of interest also for the application of photocatalytic finishing to renders in new constructions.

Laboratory assessment of the antifouling potential of a soluble-matrix paint laced with the natural compound polygodial

Polygodial is a potent and selective inhibitor of ascidian metamorphosis that shows promise for controlling fouling by ascidians in bivalve aquaculture. The current study examined the potency of, and associated effects of seawater exposure on, a rosin-based soluble-matrix paint laced with 0.08–160 ng polygodial g−1 wet paint matrix. Paint-coated surfaces were soaked in seawater for 0, 2, 4 or 12 weeks prior to screening for antifouling activity using a bioassay based on the nuisance ascidian Ciona savignyi Herdman. Mortality was greater (mean 50% lethal concentration: 5 ± 2 ng g−1; mean 75% lethal concentration: 17 ± 4 ng g−1) and metamorphosis was inhibited (mean 50% anti-metamorphic concentration: 2 ± 0.4 ng g−1; mean 75% anti-metamorphic concentration: 15 ± 10 ng g−1) in C. savignyi larvae exposed to polygodial-laced soluble-matrix paints, relative to control paints without polygodial. Soaking in seawater prior to testing reduced the efficacy of the formulation up to nearly 12-fold, but even after soaking for 12 weeks paints laced with polygodial at 160 ng g−1 wet paint matrix prevented ⩾90% of the larvae of C. savignyi from completing metamorphosis. The outcome of this experiment provides a positive first step in evaluating the suitability of polygodial-laced soluble-matrix paints for use in aquaculture.

Effect of quantity and size distribution of calcite filler on the quality of water borne paints

Calcite is the most widely used mineral filler in paint formulations. It provides not only a decrease in the cost of paint but also modifies some physical paint properties. Although some properties of calcite such as particle size distribution and refractive index are not comparable in quality to TiO2, calcite can improve the distribution of TiO2 via its interaction with TiO2 particles. In this study, calcites of different size distributions are used as filler in the architectural waterborne, acrylic based paint recipes. The quality of paints was compared to properties based on both wet and dry paint such as viscosity, density, opacity, gloss, scrub resistance and Buchholz hardness. Examination of the results identified an optimum quantity and size distribution of calcite for the paint recipe. The second series of this study involved substitution possibilities of TiO2 with calcite using seven different paint formulations. Phase images of the dry paint films obtained using “Atomic Force Microscopy” (AFM) showed the extent of distribution and aggregation of particles for each formulation on the paint surface. The overall experimental results revealed that the use of TiO2 can be decreased up to 4% by replacement of calcite with an optimum size distribution that was also supported by AFM measurements.

Paint‐on‐glass animation: the fellowship of digital paint and artisanal control

AbstractIn this paper we deal with paint‐on‐glass animation, which is a technique for making animated films by pushing slow‐drying paints from frame to frame directly under the camera. As artwork is continuously destroyed upon creating new frames, the animator is not able to rehearse or refine the animation afterwards. Furthermore, due to impracticable issues like how to stack up layers containing wet paint or how to overlay masks on the wet medium, one has to take both creative as technical decisions for each shot. Our approach consists of an interactive paint setup that physically simulates paint media. Together with a set of digital tools the artist is relieved from the difficult task of sustaining a constant frame‐to‐frame coherence while animating and is given the possibility to modify or undo earlier paint modifications. Regarding the interaction part, the artist stays in full control by employing a tangible interface. This allows artists to push pigment with their fingers, use special‐purpose digital brushes, or even to employ real life tools like paper tissue. Feedback from artists confirms the real‐life behaviour of stretching and smudging the paint as well as interacting with the setup, resulting in a natural and reality‐based methodology. Copyright © 2011 John Wiley & Sons, Ltd.

Integrated multiscale product and process control of polymeric coating curing

In automotive coating manufacturing, control of curing of thin films of wet paint on vehicle panels is always a very challenging operational task. This is especially true when both process efficiency and product quality need to be controlled simultaneously. The challenges in this task are multiple. First, coating quality is not measurable online and its characterization is multiscale in length and time. Second, coating curing is a multistage process where heat and mass transfer and polymerization take place also in multiscale of length and time, most of which are not measurable online either. In this paper, we introduce an integrated multiscale product and process control (IMPPC) scheme that can be used to control effectively the reactive drying process. By resorting to this scheme, a set of advanced methodologies for multiscale modeling, model simplification, and multiscale controller synthesis can be seamlessly integrated to construct a high-performance control system. It is demonstrated that this control system has extraordinary performance on set-point tracking and disturbance rejection. Most importantly, it offers unique opportunities to achieve all-time on-aim control of both coating quality and process performance covering a wide range of time and length scales.

High performance water-borne paints with high volume solids based on bimodal latexes

The performance of water-borne paints formulated with five different high solids content acrylic (MMA/BA/MAA) latexes was investigated. These latexes had different particle size distributions (unimodal at 61 wt% and bimodal with the large mode below or above 350 nm at 65 wt% solids), different types of surfactant and in one case the carboxylic monomer was omitted. The results showed that both the particle size distribution of the latex and the paint thickening mechanism were found to be important contributors to wet paint viscosity and dry film properties. It was found that the water-borne paints formulated with the bimodal latex with particle sizes below 350 nm provided the best application properties in terms of drying time under ambient conditions, gloss (dependant on thickener type used), and mechanical properties of the paints.

A Tiered Approach for Assessing Dermal Exposure to Constituents in Latex Paint

ABSTRACT Latex paint is commonly used by professional and consumer painters. Potential inhalation exposure to chemical vapors from paint has been studied extensively. Potential dermal exposure is not as well studied and existing exposure evaluation methods assume the paint remains wet for the duration of skin contact. However, latex paint may dry quickly and this limits the bioavailability of paint constituents due to the decreased diffusion through a dry film. This study presents a tiered in silico (i.e., computer modeling) approach to evaluate potential dermal exposure to nonvolatile substances using a technique that begins with exposure to a wet paint film and transitions to a dry film. Experiments were performed to help quantify a key parameter, latex paint drying time, and the experimental results were used in a case study to demonstrate the tiered approach. The predicted dermal penetration ranged from 100% of the applied substance for a simple conservative approach to 5% of the applied substance for the refined wet/dry film approach. Assuming the paint film was partially wiped further reduced the predicted penetration to 2%. This study addresses only latex paint but the tiered approach could be modified to evaluate other products.

Fate of a coalescing aid after latex paint application

Water-based coatings require coalescing aids to achieve properties equivalent to solvent-borne paints. A common coalescing aid in latex paints is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TMPD-MIB). The relatively large quantity of TMPD-MIB used in latex paints has raised concerns regarding its emissions to both indoor and outdoor atmospheres. In this study, a one-dimensional dual (paint and material) layer diffusion model was developed to estimate emissions of TMPD-MIB from two latex paints applied to gypsum board. The paints contained different pigment volume concentrations (PVC) and different amounts of TMPD-MIB. Different modeling approaches were used depending on the PVC of the paint. The proposed model for paint drying and TMPD-MIB emissions was tested with data from previous chamber experiments. Experimental data were first used for purposes of parameter estimation, and the model was then compared against an independent experimental dataset. The diffusion coefficient of the paint layer was adjusted as a function of the water content remaining in the wet paint film. The effective diffusion coefficient of TMPD-MIB in the paint layer was found to be dependent on the PVC and water content of the paint.

Improvement of minimum paint film thickness for THz paint meters by multiple-regression analysis

We propose a numerical parameter fitting method to determine the time delay between two temporally overlapped echo pulses in terahertz (THz) tomography measurements. The method is based on multiple-regression analysis with the least-squares method and is applied to decrease the minimum paint film thickness for THz paint meters. Applying multiple-regression analysis to paint thickness measurements is five times more sensitive with regard to the minimum thickness than numerical Fourier deconvolution. We apply the proposed method to determine the optical thickness, geometrical thickness, and group refractive index of dry paint film and wet paint film. The proposed method is useful for decreasing the minimum thickness for a THz paint meter and other THz tomography measurements.

2601 実時間2次元テラヘルツ断層イメージング法の開発(S22-1 非破壊評価とモニタリング(1),S22 非破壊評価とモニタリング)

We propose real-time two-dimensional (2D) terahertz (THz) tomography for 2D crosssectional imaging of moving objects. The proposed method does not require mechanical scanning elements for time delay and sample position, which are essential for conventional THz tomography. For this purpose, a 2D spatiotemporal THz image is acquired at a frame rate of 10frame/s by a combination of electro-optical time-to-space conversion and line focusing of a THz beam on a sample. We demonstrate the use of real-time 2D THz tomography for real-time monitoring of the paint thickness in a moving paint sample and the drying progress in a wet paint film. The proposed method provides a powerful tool for non-ionizing and non-contact probing in the fields of nondestructive testing and biomedical diagnostics.

Real-time two-dimensional terahertz tomography of moving objects

We propose real-time two-dimensional (2D) terahertz (THz) tomography for 2D cross-sectional imaging of moving objects. The proposed method does not require mechanical scanning elements for time delay and sample position, which are essential for conventional THz tomography. For this purpose, a 2D spatiotemporal THz image is acquired at a frame rate of 10 frame/s by a combination of time-to-space conversion using non-collinear 2D free-space electro-optic sampling and line focusing of a THz beam on a sample. We demonstrate the use of real-time 2D THz tomography for real-time monitoring of the paint thickness in a moving paint sample and the drying progress in a wet paint film. The proposed method provides a powerful tool for non-ionizing and non-contact probing in the fields of nondestructive testing and biomedical diagnostics.

Quality criteria of powder coated HDG steel in corrosive environment

The performance of powder coatings on hot-dip galvanized steel has been studied by testing in 5 years field exposure in marine and industrial atmospheres, as well as in accelerated tests. The aim was to assess the quality of such coating systems in corrosive environments and to establish criteria for how to obtain good quality. The test data demonstrates that polyester powder coatings are a good alternative to wet paint as top coat on hot-dip galvanized steel. The phosphate layer is identified as the most crucial step to ensure high quality. Recommendations for how to obtain good quality are provided.

Thermal wave measurement of wet paint film thickness

Thermal wave phase measurements are reported on the drying of wet paint films on aluminium substrates. Measurements of the change in thickness as the paint dries have also been obtained using a differential focussing technique on an optical microscope. By including the optical microscope measurements of the drying paint film thickness together with estimates for the density and thermal properties of the drying and cured paint, predictions have been made of the thermal phase/thickness relationships for the wet, dry, curing and cured paints. It is concluded that a phase measurement on the wet paints could be used to predict a final cured paint thickness with an accuracy of approximately ±2 μm. Errors in predicting cured film thickness from a wet film thermal phase measurement arises principally from uncertainty over the solvent content of the wet paint film, the state of cure, and the consequent uncertainty over the paint density and thermal properties.

Patterns of painting in satin bowerbirds Ptilonorhynchus violaceus and males’ responses to changes in their paint

Satin bowerbirds Ptilonorhynchus violaceus have an elaborate multi‐component sexual display, some components of which have been extensively studied. We describe a relatively unstudied component of this display, bower painting, and birds’ responses to manipulations of their paint. Males of this species focus their display around a stick bower constructed on the forest floor which they decorate with a variety of objects and paint. Painting involves a male masticating plant material and wiping the plant‐saliva mixture onto the inside walls of the bower; during courtship visits to bowers, females nibble at this paint. We found that 93% of 53 males painted their bowers at our study site and the time males spent painting their bowers accounted for 24% of their time at the bower. We experimentally removed and added paint to bowers to test whether males respond to these changes in their paint. Males gave more advertisement calls and spent less time manipulating sticks at the bower when we added fresh wet paint to their bowers compared to older dried paint or a control treatment. They did not respond to the removal of paint from their bowers, perhaps because it was primarily older dried paint that was removed. We also found that males painted more frequently when there was measurable wind in their bowers, which could have degraded the quality of the signal. Our findings indicate that fresh wet paint is more important to males than older dried paint and, together with previous work at this site, suggest that paint may act as a signal to females. Given that females nibble bower sticks during courtship, we suggest that bower paint may function as a chemical sexual signal rather than a visual signal.

The role of sag control agents in optimizing the sag/leveling balance and a new powerful tool to study this

In order to obtain glossy coatings with a high quality appearance it is necessary that surface irregularities created during paint application or during drying/curing of the paint level-out sufficiently while sagging problems are avoided. We have recently developed the so-called falling wave method that can be used to determine the sag and leveling behavior of wet paints during drying and curing in a quantitative manner. This method is very useful in identifying the cause and nature of poor coating appearance and facilitates development of paints with good sag and leveling behavior. In this paper, it is shown that thixotropy of the paint can be very useful in increasing sag resistance, improving coating appearance and widening the application window. Thixotropy can be introduced in paints by addition of, e.g. sag control agents. Various experimental examples of the beneficial use of sag control agents on the sag/leveling behavior of paints are given.

Performance of coated steel systems exposed to different mediaPart I. Painted galvanized steel

The performance of different pre-treated galvanized steel/primer/topcoat paint systems applied on hot-dip galvanized steel sheets has been studied. Each panel was pre-treated with 5% Fe(NO 3 ) 3 +15% H 3 PO 3 solution. After this step, the panels were coated either with acrylic (AC), alkyd (AK), vinyl (VL), epoxy base-solvent (ES) or epoxy-waterborne (EW) based corrosion-inhibiting primer using zinc molybdenum phosphate as anticorrosive pigment, and with commercially available alkyd topcoat paint. Experimental behavior of these panels under standardized salt spray chamber exposure or continuous immersion in 0.5 M NaCl, 0.5 M Na 2 SO 4 or 0.25 M NaCl +0.25 M Na 2 SO 4 solutions was evaluated through periodical visual inspection (blistering and rusting degrees) and EIS measurements (corrosion evolution). Initial (dry) and final (wet) paint adhesion was also determined. EIS data has been interpreted and discussed in terms of the time dependence of the electrical (paint coating) and electrochemical (steel substrate) parameters associated with interfacial processes describing the metal/paint system deterioration. According to the electrochemical properties, visual inspection and standardized tests results, the painting systems designated as AK, ES, EW, and VL presented the best overall anticorrosive behavior under immersion conditions, but all samples failed when exposed to the salt spray chamber. System AC behaved very well in 0.25 M NaCl+0.25 M Na 2 SO 4 but failed in the other media. Adhesion changes outside the tested areas showed that under immersion conditions there was lateral diffusion. Good correlation between standardized and electrochemical tests results was also obtained.

Performance of coated steel systems exposed to different media: Part I. Painted galvanized steel

The performance of different pre-treated galvanized steel/primer/topcoat paint systems applied on hot-dip galvanized steel sheets has been studied. Each panel was pre-treated with 5% Fe(NO 3) 3+15% H 3PO 3 solution. After this step, the panels were coated either with acrylic (AC), alkyd (AK), vinyl (VL), epoxy base-solvent (ES) or epoxy-waterborne (EW) based corrosion-inhibiting primer using zinc molybdenum phosphate as anticorrosive pigment, and with commercially available alkyd topcoat paint. Experimental behavior of these panels under standardized salt spray chamber exposure or continuous immersion in 0.5 M NaCl, 0.5 M Na 2SO 4 or 0.25 M NaCl+0.25 M Na 2SO 4 solutions was evaluated through periodical visual inspection (blistering and rusting degrees) and EIS measurements (corrosion evolution). Initial (dry) and final (wet) paint adhesion was also determined. EIS data has been interpreted and discussed in terms of the time dependence of the electrical (paint coating) and electrochemical (steel substrate) parameters associated with interfacial processes describing the metal/paint system deterioration. According to the electrochemical properties, visual inspection and standardized tests results, the painting systems designated as AK, ES, EW, and VL presented the best overall anticorrosive behavior under immersion conditions, but all samples failed when exposed to the salt spray chamber. System AC behaved very well in 0.25 M NaCl+0.25 M Na 2SO 4 but failed in the other media. Adhesion changes outside the tested areas showed that under immersion conditions there was lateral diffusion. Good correlation between standardized and electrochemical tests results was also obtained.