Properly dilute the varnish for the car is necessary immediately after the completion of the stage of applying the base enamel, since the viability of the finished mixture is limited by the time of polymerization of the hardener. If you make an error in the proportions of the components during the mixing stage, the coating will either flow, forming irremovable floods, or dry with matte spots and low hardness. Accurate adherence to the technology of preparing the working solution is a critical factor affecting the depth of gloss and the durability of the protective layer of the body.
The process of preparing the working solution begins with an assessment of the ambient temperature and the selection of the appropriate type. hardenerThis is the component that triggers an irreversible chemical reaction. In professional workshops, special measuring tanks with calibration are used, where the scales of the ratio of components have already been applied, which eliminates the need for complex mathematical calculations. For quality results, it is important to use only original solvents and hardeners of the same series as the main varnish, since the chemical composition of different brands can be radically different.
The viscosity of the finished mixture must strictly comply with the manufacturer's requirements specified in the product technical passport and be checked using a viscometer funnel. Too thick composition will lie “orange peel”, which is almost impossible to polish without damaging the thickness of the layer, and excessively liquid will provoke the formation of undertone on vertical planes. Critically
Selection of components and preparation of the workplace
Before mixing the components, you need to prepare a clean workplace and make sure that all the necessary ingredients are available, including two-component acrylic varnish, hardener and solvent. The quality of the final coating depends on the purity of the dishes, as even microscopic dust particles or remnants of old material can spoil the whole result. It is recommended to use disposable graded cups or carefully washed stainless steel containers.
The choice of hardener type is determined by the temperature in the paint shop, and ignoring this parameter is one of the most common causes of marriage when painting. Manufacturers produce three main types of hardeners, each designed for a specific temperature range:
- 🌡️ Quick hardener - used at temperatures below +15 ° C, provides accelerated drying, but reduces the time for spreading.
- 🌡️ A normal hardener - optimal for temperature conditions from +15 ° C to +25 ° C, gives a balance between drying time and spreadability.
- 🌡️ Slow hardener - is used at temperatures above +25 ° C, prevents the boiling of varnish and the formation of craters.
The solvent acts as a regulator of viscosity and evaporation rate, and its amount depends on the required consistency for a particular spray gun. Do not use aggressive solvents, such as 646 or 647If not recommended by the varnish manufacturer, as they may cause clouding or color change of the base. For work, specialized diluents with the marking "for acrylic varnishes" are best suited.
⚠️ Attention: Never use nitro-based solvents to dilute two-component varnishes, as this will disrupt the chemical structure of the coating and loss of adhesion.
Mixing proportions and cooking technology
The basis of the qualitative result is the exact observance of the mixing proportions, which are always indicated on the label of the can with varnish or in the technical sheet (TDS). The standard ratio for most automotive varnishes is a 2:1 scheme, where two parts of the main material account for one part of the hardener. However, there are systems with ratios of 3:1, 4:1 and even 1:1, so blindly following the usual proportions without reading the instructions is unacceptable.
The mixing process should occur in stages: first, the required amount of varnish is poured into the measuring glass, then a hardener is added, and only after that, if necessary, a solvent is introduced. The components must be thoroughly mixed with a clean wooden or plastic spatula for 2-3 minutes, paying attention to the bottom and walls of the container so that there are no undissolved clots.
To control the quality of mixing, you can use a table of conformity of components and conditions of use, which will help to avoid errors in the selection of materials:
| Type of system | Proportion (Luck: Hardener) | Temperature of application | Time to dry |
|---|---|---|---|
| HS (High Solid) | 2:1 | +20°C | Standard |
| UHS (Ultra High Solid) | 3:1 or 4:1 | +20°C | Accelerated. |
| MS (Medium Solid) | 2:1 | +15..+25°C | Long-term |
| 1K (Single Component) | No, he doesn't. | +18..+22°C | Very long. |
After adding all the components, the mixture should settle for 5-10 minutes (dehydration time) so that air bubbles formed during stirring leave the solution. If you apply the varnish immediately after shaking, microcraters or bubbles may appear on the surface, which will spoil the gloss. The finished material should be strained through a funnel with a mesh of 125-190 microns before pouring into the spray gun tank.
Adjusting viscosity and setting up the spray gun
The correct viscosity of the varnish is a key parameter that determines how the material will lie on the surface of the body and form a glossy film. To measure this indicator, a viscometer is used, which is a funnel with a calibrated hole through which the liquid drains. The expiration time of a certain volume of varnish through the viscometer opening (usually 4 mm) should be from 14 to 18 seconds at a temperature of 20 ° C.
If the leakage time is less than 14 seconds, the varnish is too liquid, and it must be added a little basic material or allowed to settle for the evaporation of volatile fractions. In the case of a time exceeding 18 seconds, the mixture is too thick and a small amount is required. solventAfter that, the measurements must be repeated.
- 💧 Too high viscosity leads to poor spreading, shaven and the formation of an “orange peel”.
- 💧 Too low viscosity causes abundant formation of undertone, a decrease in the thickness of the dry residue and a loss of shine.
- 💧 Optimal viscosity ensures self-spreadability of the material and the formation of a smooth mirror surface.
The setting of the spray gun also depends on the viscosity of the material: for thicker varnishes, greater pressure is required at the exit of the nozzle and a wider spray torch. Air pressure is usually set in the range of 1.2-1.5 bar at the exit of the nozzle, but the exact values should be sought in the manual to the specific spray gun and varnish.
⚠️ Attention: Do not attempt to correct varnish defects by adding a solvent to the already applied layer – this will lead to uneven drying and chemical conflict of the layers.
Typical mistakes in the dilution of varnish
One of the most common mistakes is the use of expired components, especially hardeners, which eventually lose their properties and stop catalyzing polymerization. Even if the shelf life has only expired by a month, the chemical structure of the hardener can change, causing the varnish to remain sticky or shrivel a few days after painting.
Another common problem is the wrong mixing order, where users first pour the solvent and then add the varnish and hardener. This sequence often leads to the formation of insoluble clots and heterogeneity of the mixture, since the concentrated hardener reacts with the varnish in the local zone to a uniform distribution.
☑️ Checklist before painting
Ignoring humidity can also play a cruel joke: at humidity above 75% on the surface of fresh varnish can act matte plaque, known as “whitening”. This is due to the condensation of moisture from the air on the cooling surface of the evaporating solvent, which violates the transparency of the coating.
Lifetime of the mixture and conditions of application
The term “pot-life” means the period during which the diluted varnish retains its working properties and is suitable for application. After mixing with the hardener, irreversible polymerization processes begin in the material, and the viscosity gradually increases, making high-quality spraying impossible.
Usually, manufacturers indicate a life of about 2 hours at a temperature of 20 ° C, but it is worth considering that with an increase in temperature, this period decreases, and with a decrease - increases. If you did not have time to use up all the prepared varnish during the specified time, it should be disposed of, since the application of thickening material will lead to marriage.
How do you extend the life of the mixture?
You can cool the finished mixture a little (but not below +15°C) to slow down the reaction, however, this is risky and can affect the viscosity. It is better to dilute the varnish in small portions.
The temperature of the material itself also matters: before applying the varnish, the hardener and solvent must have a shop temperature (about 20 ° C). The use of cold components can lead to condensation loss and changes in viscosity, which will require re-adjustment.
Safety and waste management
Car lacquers and hardeners contain toxic organic solvents and isocyanates that are hazardous to health when inhaling vapors and contacting the skin. These materials should only be handled in a well-ventilated room or paint chamber with an effective air filtration system.
The use of personal protective equipment is a mandatory requirement: you must wear a respirator with carbon filters of protection class A1P1 or A2P2, protective glasses and nitrile gloves. Getting a hardener on the skin can cause a severe allergic reaction or a chemical burn that heals for a long time.
- 🧤 Skin protection Use tight gloves and workwear that covers your arms and neck.
- 😷 Breath protection The respirator should fit tightly to the face, excluding the sucking of untreated air.
- 👓 Eye protection. - glasses will prevent spray of varnish and solvent vapors from entering the mucous membrane.
The remaining varnish can not be poured into the sewer or soil, as it pollutes the environment. Hardened residues of varnish and used containers should be handed over to special points for the disposal of hazardous chemical waste, observing environmental standards.
Expert advice: Always label mixed varnish with cooking time on the label so as not to use material with an expired life.
Frequently Asked Questions (FAQ)
Can you dilute the thickened varnish with an additional solvent?
Add the solvent can only be within the manufacturer's recommended 10% of the volume of the mixture. Exceeding this limit will reduce the dry residue, which will lead to loss of shine, reduced coating hardness and possible clouding of the varnish after drying.
What to do if the lacquer after drying became matte?
Mattiness (whitening) most often occurs due to high humidity, draft or the use of a quick solvent in the cold. The surface will have to be sanded and repolished, and in difficult cases - repainted in compliance with the temperature regime.
How long does the varnish dry before polishing?
The time of full polymerization depends on the type of varnish and drying temperature. When drying naturally, it takes 12 to 24 hours, and in a chamber at 60°C - about 30-40 minutes. You can polish only after complete cooling and hardening.
Can I mix the different manufacturers?
It is strictly not recommended to mix the bases and hardeners of different brands or series. The chemical composition may not match, resulting in a lack of adhesion, wrinkling, or perpetual stickiness of the coating.
How to clean the spray gun after working with the varnish?
Immediately after the work is completed, wash the tool with a suitable solvent for acrylic varnishes. Disassemble the dusa and needle, remove the residues of the material with a soft brush, lubricate the moving parts and collect back to avoid corrosion.