General Problems

Blushing

Generally caused by high humidity and temperature. The paint will appear to be blotchy, milky, or cloudy. This is very common in lacquer paints, but is also seen in other paint systems as well. The solvent evaporation can cause the temperature to dip below the dew point which will cause moisture to develop into the paint film. High humidity used in combination with a fast or non compassable thinner will further aggravate the problem.

 

To repair the problem:

If the paint has not cured apply heat to the surface using either a heated paint booth or a common heat gun.

If you are experiencing blushing after a first coat you can add some retarder or a slower reducer/thinner. Using a slower drying paint thinner will allow the water molecules to evaporate before the film locks the water in.

If the paint has dried you can try to buff the finish to a gloss, however in most cases you can expect to sand and repaint the substrate in better painting conditions.

 

Solvent Popping

Solvent pop happens when solvent becomes trapped in the paint and the paint surface forms a skin surface preventing evaporation. When solvents do leave the paint film the pop through the surface rather than normal evaporation. Solvent pop looks like pinholes, tiny craters, or little pop marks. Solvent popping ca happen from using a thinner too fast for the ambient temperature, insufficient flash time in between coats, or the application of coats too heavy.

You cant repair the problem. You will need to sand down the finish and repaint it. Use a slower thinner, wait longer in between coats, and apply less material.

 

Orange Peel

Orange peel is very common, it will appear to have a texture like an orange. Using insufficient air volume and/or pressure or not using enough paint thinner will greatly effect the flow out of sprayed paints. If the pressure is too low the paint will not atomize properly. If the paint thinner it too fast it will evaporate before allowing the paint to flow out. Extreme heavy coats will cause a heavy pattern once it is dry. Piling on thick coats may get rid of orange peel upon application but will show up before the paint is dry. In order to remove the orange peel sand the finish with wet sandpaper and then buff it with a high speed buffer.

 

Dieback, Loss of Gloss

Loss of gloss can happen from many things. Applying too much paint whether the coats are too heavy or too many coats without a long enough dry time between coats. Using a low grade thinner may also be a factor in the same problem. If the primer or color or other undercoat has not properly dried solvent may be trapped and will evaporate slowly causing dieback. Of course not using enough paint or a clearcoat will cause the finish to never shine well. If you spray the paint in an enclosed booth the paint thinners may evaporate, but if they do not have anywhere to go it can settle right back on the finish making it dull. Also if the surface you are painting is porous solvents can be absorbed into the surface and then later want to release through the new finish(example detiorating paint). In a catalyzed paint the surface is chemically cured and will not allow the solvents to penetrate through the surface. Solvents will definitely over time find a way to escape through which leave tiny microscopic holes which at a normal viewing look as though it is not as shiny as it should be. In an automotive finish it can take about one month after a new paint job. In most cases the remedy is to simply use a high speed buffer. The type of rubbing compound, glazes, and pads may change upon application. Extreme cases may need to be sanded down and refinished. Old paint will ultimately lose gloss under exposures to UV sunlight, humidity, dirt, salts, abrasions, and chemicals or a combination of several of these factors.

To prevent loss of gloss or dieback pay attention to directions. Use the right reduction ratios and the appropriate thinner for the job. Wait the recommended drying times in between coats. Apply the right amount of paint on the coat. Use an electronic film thickness gauge to determine how much paint you applied if you have a recommended mil thickness. If you apply to much paint per coat you may need to adjust your air pressure and the fluid nozzle of the spray gun. With training using a high quality paint will normally have less problems in application and will hold its gloss much longer than a generic paint.

 

Runs, dripping paint

This problem is very easy to spot. The paint starts to drip and it dries with the running finish where the paint forms a drip motion. It is caused by using too much thinner or using thinner that will not evaporate quickly enough. If the paint has not dried long enough in between coats or a double coating application it will keep the paint thin enough to run down especially on a vertical surface. Cold metal or cold paint temperature and your paint gun setup may have a few factors to be aware of.

 

 

 

 

Flaking Paint, Delamination

When paint has an adhesion problem it is commonly prepped incorrectly or not prepared for painting at all. Most surfaces need to be properly cleaned and sanded or scuffed with a grit appropriate for the coating. Sometimes the omission of primer or using a primer incompatible for the surface can cause paint delamination. For instance certain primers need an etching or wash primer to convert the surface. Plastics need types of primer for adhesion. Fiberglass and gel coats can be tricky too. If you put a paint layer on after the maximum recommended dry time the re-coat window may have expired. Each layer will have a difficult time melting into the previous layer. Not using enough of the paint will have bad film integrity and will fail. On occasion it is possible using incompatible products may be the cause of flaking paint. Certain paints will not go over others. On a flexible product like plastic may require a flex agent or paint rubberizer wen using a brittle paint like lacquer. Flex agent is not always the answer because it can both soften the film and cause the clearcoat to yellow sooner. Use recommended amounts of it.

 

To fix delamination you will need to sand it down and repaint it. Sometimes you can feather sand it until the paint has a good grip, or you will need to sand it bare down to the primer or bare surface.

 

Bleeding

Bleeding is when pigment from an undercoat bleeds though the paint layers discoloring it. Discoloration is very common when you paint a white paint over a red paint. To avoid Bleed though you can either sand to completely remove the undercoat or use a compatible 2 component catalyzed primer or sealer.