What are the differences between a primer and a primer surfacer?
What will be an ideal response?
Primers come under the national VOC regulation, and are allowed to contain a maximum of 6.5 pounds of VOCs per gallon of coating. They are used instead of metal cleaner and conversion coatings. They are generally used on bare metals that are smaller in size and are less likely to develop corrosion. They too contain an acid, which etches into the properly prepared metal surface, but the acid that is contained in them will stop by itself if the proper airflow is available.
Primer surfacers are undercoats that provide adhesion to the surface they are sprayed on and adhesion to that which is sprayed over them. They also provide light filling qualities, which means that when applied to an area, they will provide a film build that can be sanded to remove small imperfections. They are allowed by the national VOC regulation to contain no more than 4.8 pounds of VOCs per gallon. Primer surfacers are sometimes referred to as primer fillers, and generally have a recommendation of applying 2 to 4 coats with a dry film build of 2 to 2.25 mils per coat. That can mean a film build can be as much as 8 to 10 mils of fill before sanding. That is not to say that primer surfacer should be sprayed and left that thick. In fact, most paint makers recommend a 2mil thickness film build after the surface has been block sanded. If an imperfection of 3 mils has 5 mils of primer surfacer applied over it, then 2 mils are sanded off where the imperfection will no longer be seen. The primer surfacer has “leveled” the substrate, and
the imperfection is removed
You might also like to view...
The early industrial robots were mainly ____________________ robots used to move material with little repetitive accuracy required.
Fill in the blank(s) with the appropriate word(s).
Which of the following would be a good source of information for an external scan?
A) Employees B) Suppliers C) Customer contact personnel D) The company owner
By definition, ____________________ devices are all devices outside the processor, including all hardware.
Fill in the blank(s) with the appropriate word(s).
Answer the following statement(s) true (T) or false (F)
1. Good conductors have many free electrons in their structure. 2. Once charged, a capacitor can remain charged forever. 3. Any inductance coil is really a combination of inductance and resistance in series. 4. All capacitor manufacturers use a standard set of color codes. 5. A positive temperature coefficient indicates that the capacitance will decrease with an increase in temperature.