To obtain the optimal viscosity of the anti-gravel composition BODY 930, it is necessary to use specialized nitro-based or solvent-based solvents, adding them in an amount of 5-10% of the total mass of the material immediately before application. Excessive dilution causes the coating to run off vertical surfaces, and working with the factory consistency often causes uneven spraying and the formation of a “shagreen” surface that does not dry well. The correct selection of the chemical component directly affects adhesion to the metal, the elasticity of the layer after drying and the ability of the material to effectively absorb noise and vibration.
It is important to consider that BODY 930 is a bitumen-rubber mixture that is sensitive to aggressive chemical environments, so the use of unsuitable liquids can destroy the structure of the polymer even at the preparation stage. If you use a evaporator that is too fast in hot weather, a film will instantly form on the surface, under which the solvent will remain preserved, causing the coating to swell. Conversely, a slow solvent in a cold garage will prevent the material from setting and it will collect dust and dirt.
Selecting a suitable solvent for bitumen mastic
The basis for diluting this type of anti-gravel are organic solvents that can effectively dissolve bitumen and rubber fractions without changing their chemical structure. The most common and affordable option is white spirit or nefras, which provides a smooth decrease in viscosity. However, for professional treatment of the bottom, more aggressive mixtures are often used, such as solvent or specialized nitro solvents (for example, 646 or 647), which guarantee the homogeneity of the mixture.
⚠️ Attention: It is strictly forbidden to use water, pure acetone or gasoline to dilute BODY 930. Water will cause the emulsion to separate, acetone can curdle the rubber, and gasoline will make the coating a fire hazard and take a long time to dry.
When choosing a liquid, you need to pay attention to the evaporation rate. For work in closed boxes with good ventilation, fast-volatile compounds that speed up the drying process are suitable. If the treatment is carried out outdoors or in a cold room, it is better to choose a solvent with slow evaporation so that the material has time to spread and form a monolithic layer. Solvent for anti-gravel must be clean, free of any oil or water that may float to the surface after drying.
Solvent compatibility
The compatibility chart shows that white spirit is suitable for basic thinning, solvent for degreasing and strong thinning, and xylene for increasing adhesion. Mixing different types of solvents is not recommended to avoid chemical reactions.
Optimal mixing proportions of components
The factory consistency of BODY 930 is designed for application with a spatula or brush, so when working with an air gun or compressor sprayer, density correction is required. The manufacturer's standard recommendation is to add 5-10% solvent by volume of the jar. Exceeding this threshold, for example, dilution by 20-30%, will result in anti-gravel coating will lose its noise-insulating properties and become too thin, ceasing to serve as protection against gravel impacts.
- 🔹 For an air gun with a 3.0 mm nozzle, add 5-7% solvent to create a stable torch.
- 🔹 For high-pressure compressor units, it is allowed to increase the solvent share to 10% for better atomization.
- 🔹 When applied with a brush to hard-to-reach places (spar pockets), the material can not be diluted or added no more than 3%.
- 🔹 In the cold season (below +10°C), the proportion of solvent can be increased by 2-3% to compensate for the thickening of bitumen.
The mixing process must take place in a clean container. First, open the jar of material and thoroughly mix the contents with a mixer or long spatula, lifting the heavy fractions from the bottom. Only after homogenization of the base composition should you add solvent in small portions, constantly monitoring the viscosity. If you are using BODY Thinner 747 or its equivalents, be careful not to exceed the maximum permissible percentage of volatile substances.
The golden rule: it is better to under-thin and apply a second coat than to make the mixture too thin and end up with drips that have to be cleaned up.
Technique for applying diluted anti-gravel
The quality of the final coating depends not only on what you diluted the mastic with, but also on the method of applying it to the body. After preparing the surface (washing, drying and degreasing), the material is applied with uniform movements. The air gun should be held perpendicular to the surface at a distance of 20-30 cm. When working with a diluted composition, it is important not to linger in one place to avoid the formation of drops.
☑️ Checklist before application
Pay special attention to welds and hidden cavities. Here BODY 930 often applied through special extension nozzles. In such cases, the viscosity should be as low as possible for a given type of sprayer, so that the composition penetrates deep into the joints, but does not leak out completely. After applying the first layer, it must be allowed to dry for 15-30 minutes (depending on temperature and type of solvent) before applying the second.
If you are working with a roller or brush, the technique changes: the movements should be rubbing to squeeze air out of the pores of the material and ensure close contact with the metal. Bitumen mastic when undiluted, it applies well with a brush, filling in micro-irregularities. When using a diluted composition with a brush there is a risk of leaving streaks, so the final smoothing must be done quickly.
The influence of temperature and humidity on drying
Temperature plays a critical role in the polymerization process of anti-gravel. At temperatures below +15°C, solvent evaporation processes slow down and the material remains sticky for a long time. Under such conditions, using too slow solvent will cause dust and debris to adhere to the surface, ruining the appearance and protective properties. The optimal temperature is considered to be from +20°C to +25°C.
| Air temperature | Drying time "from dust" | Complete polymerization time | Solvent Recommendation |
|---|---|---|---|
| +10°C... +15°C | 40-60 minutes | 24-36 hours | Fast (nitro) |
| +20°C... +25°C | 20-30 minutes | 12-24 hours | Standard |
| +30°C and above | 10-15 minutes | 6-12 hours | Slow (with retarder) |
| Below +5°C | Doesn't dry | Does not polymerize | Heating the room is required |
High humidity also negatively affects the quality of the layer. Moisture can be preserved under the film BODY 930, causing corrosion of the metal under the coating instead of protection. If humidity exceeds 75%, it is recommended to increase the intercoat drying time or use dehumidifiers in the work area. Fast-drying solvents in high humidity conditions can cause the effect of “whitening” of the varnish film (if any) or clouding of the bitumen layer.
Elimination of defects due to incorrect dilution
Violation of the mixture preparation technology often leads to visible defects. If after drying the surface becomes matte and rough (“shagreen”), this is a sign that the solvent evaporated too quickly and the material did not have time to spread. In this case, polishing the surface or applying a thin correction layer with the addition of slow-release helps. solvent. The cause may also be insufficient filtration of the material before pouring into the tank.
The appearance of craters or fish eyes indicates the presence of grease on the body surface or the use of an incompatible solvent that has reacted with silicone or oil residues. Anti-gravel defects in the form of swellings indicate that the solvent did not have time to evaporate and began to expand under the influence of heat or sun. Such areas must be cleaned down to the metal and the coating must be reapplied, following the technology.
⚠️ Attention: If the material begins to set in the gun tank, do not attempt to re-dilute it and continue working. This will cause the nozzle to clog and cause uneven spray. It is better to rinse the instrument and prepare a fresh portion.
To remove fresh stains, you can use a rag soaked in the same solvent that was used to dilute the material. You need to act carefully so as not to smear the bitumen over a large area. If the coating has already completely dried, mechanical removal (cutting with a knife or spatula) will be the only effective method of correction.
Safety precautions and waste disposal
Working with bitumen mastics and organic solvents requires strict adherence to safety measures. Solvent vapors are toxic and flammable, so all work should be carried out in a well-ventilated area or outdoors. Usage respirator with a carbon filter and protective gloves is a mandatory requirement, since contact of the solvent with the skin causes irritation and degreasing.
Cleaning tip: The easiest way to clean the tool is immediately after use, before the material hardens. Soak the gun parts in a container with solvent or white spirit for 15-20 minutes, then blow with compressed air.
Disposal of mixture residues and flushing liquids must be carried out in accordance with environmental standards. Do not pour used solvents or cleaners into drains or soil, as this causes serious harm to the environment. Collect leftovers in sealed containers and take them to a designated hazardous waste collection point. Store open jars with BODY 930 and solvents should be kept away from sources of fire and direct sunlight.
Can BODY 930 be mixed with other anti-gravel compounds?
Mixing products from different manufacturers is not recommended, since the chemical composition of the base and solvents may differ. This may cause the material to delaminate, change color or lose elasticity. If you need to add volume, it is better to use material of the same brand and series.
How long does it take for BODY 930 to dry before it is fully used?
Surface drying takes 20-40 minutes, but complete polymerization and a set of performance properties occurs within 12-24 hours at a temperature of +20°C. During this period, it is not recommended to wet the car or drive on dirty roads.
Do I need to prime the metal before applying anti-gravel?
Yes, acid or epoxy primer is required on exposed metal areas. BODY 930 is a finishing coat and does not have the anti-corrosion properties of a primer. Old but durable coatings can be applied directly after degreasing.
How to clean clothes from spilled anti-gravel?
You can try to remove fresh stains with white spirit or a special bitumen cleaner. The frozen material is practically not removed from the fabric, so it is recommended to work in special clothing that you don’t mind throwing away.
Can I paint over BODY 930?
Yes, acrylic or polyurethane paints intended for body repair can be applied over dried anti-gravel. However, it is recommended to first carry out a compatibility test on a small area to ensure that there is no reaction between the layers.