QUALITY CONTROL IN PLANT
ISO-9001:2008, AAR M-1003 CERTIFIED
The following information is a basic guide that can be helpful not only in keeping track of the various paint systems that your shop is applying, but also a brief checklist as to what to look for when certain problems arise.
Initially, it is a good idea to copy the following information off of the paint container:
- Product Name
- Batch Number
- Date of Paint
- Expiration Date
If you believe that the paint is suspect due to some problems that you have encountered, please have this information available. We keep a retain of every batch of paint we manufacture for any shop.
When we visit any shop, some additional information we record is the shop environmental condition and equipment.
- Pump: (Bulldogs 30:1)
- Pump: (King 45:1)
- Pump: (President 27:1)
- Tips: 5/15 – 6/21 etc.
- Line Sizes and Lengths: 1/4” x 1/2”/50-200 ft.
- Pump Pressures: 1500-4500 psi
- Booth: Down Draft/Side Vents/Up Draft, etc.
- Scaffolding: Scissor Jacks, Ladders, etc.
- Number of Painters
- Ovens and Temperature
- Paint Temperature
- Air Temperature
- Booth Temperature
- Surface Temperature
- Dew Point
- Blast Conditions: SSPC-SP 5/10/6/7 / Profile Depth / Blast Media (sand-grit-shot)
WHPC/WHIC technical reps. always record what car group or file the paint system is being applied to. We record steel numbers and stencil numbers along with dry film thickness readings. Also, if an interior lining is being done, any information on holiday testing that was conducted, and if there were any defects in the film, and where the defects were located.
Even though waterborne coatings need to be handled differently than conventional solvent paint, similar problems may still occur. Subsequently, when investigating some of the more common problems, certain things should be taken into consideration.
- If sags and runs are a problem:
- Check the mil specs, painters may be trying to hang more mils than paint can hang.
- Check to see if wet mil gauges are being used, without this simple piece of equipment the painters are only guessing.
- Check the temperature and viscosity of the paint. If the paint is exceptionally warm, its viscosity will be less and it will flow more, which may cause sags. If the paint’s viscosity is thin, it will obviously have a hard time hanging.
- Check to see if anyone has added, for any reason, H2O or a co-solvent to the paint. Too much, or in the case of most of our waterbase products, it does not take a lot of water to hurt the hanging power of the paint.
- Check the dew point. If the car was sprayed when the surface temperature was not at least 5-7 Degrees. F. above the dew point, sags and runs most likely will occur.
- Check the size of the tip being used. Too large of an orifice or too small of a fan pattern can reduce atomization which will hurt hanging.
- Check to see if painters are too close to the unit, lack of fan pattern effects atomization and hanging power.
- If any dry spray is present:
- Check pump pressure. Waterborne coatings do not like high pump pressures. These materials dry fall, subsequently; any particular matter that is thrown up into the air will be tack free when it hits the ground.
- Check the tip size. Smaller orifices can restrict proper atomization, which will not allow the paint to keep a wet edge.
- Check the car temperature. When the temperature of the car is extremely hot, it is very hard to keep a wet edge, thus creating dry spray.
- Check the way the painters are applying the coating. As outlined in our Thermalbond Kit, using two painters in tandem, along with proper overlapping and distance from the car, painting bottom-up, will eliminate dry spray.
- Check shop airflow. Excessive air movement when spraying the car can alter the fan pattern and actually start to dry the paint before it reaches the car.
- If pinholes are detected:
- Check pump pressure. Holes may be blowholes.
- Check the distance from the car. The paint requires proper atomization. If the painters are too close, this can also produce holes in the wet film.
- Check the blast profile. If it is exceptionally deep, the holes may be caused due to the peaks protruding through the paint film.
- Check the blast media. If it has become contaminated, it may deposit some foreign material on the surface de-wetting the coating.
- Check the viscosity of the paint. If the body of the coating has increased, flow and leveling may be affected.
- If the finished car looks blotchy or dull:
- Check the paint expiration date. All paints have a shelf life.
- Check the dry mils. If they are low, you may be seeing some profile.
- Check the painter’s technique. A waterborne coating need 30% overlapping and even passes. Water does not flow like solvent type coatings.
- Check to see if any chalk or grease has been left on the car. Both are detrimental to a glossy finish.
- If your paint has congealed or separated:
- Water emulsion coatings fall apart if they have been frozen. Once this has happened, the paint cannot be salvaged. Water solution coatings will usually start to separate if they are one or more years old. If this occurs, in many cases a simple pH adjustment or solvent addition can be made to salvage the paint.
- If you encounter trash on the car:
- Check to see if any skins have formed on the open paint and were not properly removed or filtered out when spraying.
- Check your intake tube. A screen should be used to reduce the chance of any trash being carried to the lines.
- Check to see if the waterborne coating is not cleaning out the old material from your lines and pumps, if you are using the same equipment to spray both H20 and solvent.
- Check to see if the trash you are seeing is not really dry spray, especially if there was a primer applied first.
- If you encounter the paint lifting/peeling:
- Check for contamination on the substrate.
- Check to make sure car has adequate blast profile.
- Check to see if the car may have been frozen prior to painting. As it thaws, the paint will lose adhesion.
- Check to see if a primer was used. The two systems may not be compatible.
- Check to see if the car was pushed outside in the cold or rain too soon. If the paint was not allowed to flash off its water, it will freeze and lose adhesion.
- Check to see if the car was put into the wrong service. Certain coatings are not recommended for various acids, caustics, etc.
- If flash rusting or weld staining occur:
- Check just where the defect is. If it is on the metal sheets, it may be due to low mils.
- Check your profile. If it is very deep, you may not have covered the peaks from the blast.
- Check to see if the red spots are only on the welds. Weld staining is not rust but a unique situation that occurs when our emulsion coatings come in contact with certain types of welds.