Care and proper painting with a spray gun
With a sprayer, you can cover large items with a uniform, thin and smooth finish layer not for hours, as it was done before, but in minutes. It makes it easy to apply such compounds as nitrolaks and toners. See: Best paint sprayer for cabinets and furniture.
Paintwork materials are sprayed on the surface by a wide and slowly moving air jet (slower than in conventional spray guns with a compressor), so with HVLP systems, the loss of composition from spraying into air is significantly reduced. This means that less paint, stain or varnish will be blown away by the wind when working on the street, and less settling fog will be in the workshop. Whether you are an amateur cabinet maker or a professional furniture maker, these systems are designed specifically for you, as you can see when reviewing the review of HVLP-systems in the previous article. Regardless of the chosen model, follow our advice, practicing on trimming the boards, before proceeding to finish the next project.
Prepare a place of work
At spraying of finishing compositions on the basis of organic solvents in the room there is an unpleasant smell and, what is worse, poisonous and explosive evaporation. Therefore, if you do not have a special room equipped with explosion-proof luminaires and a fan, use water-based formulations. First of all, take care of good ventilation. The flow of fresh air should occur behind your back, pass around the workpiece in the direction of spraying and carry with it odors and excess aerosol mist. This should be the case when working with water in a basement equipped with a ventilation system, and when applying lacquer in fresh air with a light wind. To work outdoors, select a shaded place, closed from gusts of wind, carrying dust and dirt from a nearby road. Look where the excess aerosol mist will be carried away, and then check the thermometer and hygrometer readings.
To measure the viscosity of the composition by means of a viscometer, the time is noted for which the liquid will completely flow out of the funnel. Fill the funnel with the composition before turning on the stopwatch.
We advise you to work at a temperature of + 15 ° to + 30 ° C and with an air humidity of not more than 55%. When working with water compositions in the room, we recommend using an improvised painting chamber for small and medium sized products, which is easy to manufacture.
To do this, cut one side of the cardboard box, make on the opposite side a fan hole, closed with a cheap filter from the kitchen hood. Direct the flow from the fan to an open door or window and make sure that there is fresh air in the work area. Equipping a place for finishing large projects, place the fan directly in front of the window or door in a dust-free place. Hang the transparent plastic curtains-screens, descending from the ceiling to the floor, and press their lower edge to the floor. To better control the application of the coating, install at least one bright luminaire at the work site. Skew illumination will help to identify streaks, dust and missed places. Halogen lamps give bright illumination, close to the spectrum of sunlight.
During operation, the product should be accessible from all sides, but try not to touch it with your hand, so as not to spoil the freshly applied layer of finish. Place small objects on the edge of the board or a piece of cardboard so that they can be rotated in different directions, without removing it from the painting chamber. A turntable can help you better cope with this task. For work with large and heavy products make a special platform, attaching to the piece of thick plywood from below the swivel wheel bearings.
Prepare the finishing compound
The air passing through the atomizer performs two tasks: atomizes the liquid into the smallest droplets to create a smooth layer on the surface to be cleaned and brings the resulting fog to your product. Due to the low pressure in HVLP systems, viscous formulations, such as latex paints or alkyd enamels, have to be diluted more strongly than liquid nitrolac or water-based formulations. The smaller the power of the turbine in the HVLP-system, the more it will be necessary to dilute the finishing compounds.
First of all, get rid of sediment and dirt by straining the composition through a medium-density filter paper. If there is a viscometer, determine the time for which the liquid flows out of it, and compare the readings of your stopwatch to the recommendations of the system manufacturer. If there is no viscometer, no recommendations, then by trial (trial and error) select the most suitable working
viscosity by adding an appropriate solvent. This is done so. Pour in the reservoir of the sprayer accurately the quantity of the finishing composition, for example 340 ml. Set the flow of fluid and air flow to maximum. Set the maximum and width of the torch. Paint a small test area and check the spray quality, making sure that the undiluted compound passes through the nozzle and is finely atomized by the airflow. If the composition is sprayed with large drops or not sprayed completely, add 5% of the appropriate solvent to the contents of the tank. Check the spraying quality of this mixture and continue to dilute the viscous compound, each time adding 5% solvent, until the liquid is sprayed like fog.
Test diluted and undiluted compounds, reducing the width of the torch and the flow of liquid through the colorful nozzle. Do this until the spray quality becomes the same as with a wide flame. If you do not use the narrowest torch, you do not need to reduce the airflow. Write down the name of the finishing compound and the proportion of the mixture with the solvent. Compositions on organic solvents can be diluted by more than half, but water-based formulations work best when not more than 10% water is added. If this is not enough, use a colorful nozzle with a larger diameter hole complete with a new needle. A larger nozzle opening will allow the spraying of viscous formulations, in some cases even latex paints. Reducing the degree of dilution of the formulations to produce a thicker film, you can finish the finish sooner.