I am workign on my 1978 ford f-250. I am trying to get the bodywork done is there anytricks to finding lowspots on the truck?
thanks,
Jimmy

 

If your are just getting ready to start sanding and looking to see where the worst low spots are, put the truck out in the good daylight, get some one to run water slowly down over panels while you stand beside of it and look down real close, along the wet panels to find the the low spots. If you have already started sanding, and are looking for the small low spots, you can find them by using a flat sanding block , then you will see where the block sandpaper is not cutting down in the low spots. ..

If you have sanded well already , and are looking for the really small low spots, the same ones that WILL show up AFTER that 300 dollar a gallon paint is on, take a trip to your paint jobbers store. They will carry a product called 3M dry guide coating that works great. If the 3m is too costly for your budget, you can spray black aerosol lacquer paint over the panels as a guide coat, let it dry, then block sand it back off. The low spots will show up as unsanded spots with black paint in them. good luck..

 

ok thank you very much. Yes I am looking for the very very small lowspots. I work outside so after sanding the truck i always use spraypaint primer to cover up what i have done. I gues I will just put another color on and block one more time to really pick the littls spots out. I was wodnerign since i am using spraypaint when ever i go to put primer sealer on the truck will i have to sand all of that spraypaint primer off?
thanks,
jimmy

 

Lacquer primer is NOT a good substrate for today's urethane paints, and should be removed. By sanding ALL of the aeresol paint back off , is the only way of knowing that every MM of the panel is being tested for low spots or dimples. Whether one uses a dry guide coat like the 3m, or spray bomb lacquer, it all still needs to be sanded off to achieve what you are trying to do with it, find LOW spots. To get a GOOD paint job , it has to start out in the prep/ body repair and end there. Paint does not cover up panel imperfections, it makes them stand out worse. Prep is 97 % of the HARD labor in painting a car /truck, the actual spraying on of the paint is the only fun part. good luck to you

 

You can also use the old trick we used to use in the drywalling trade when prepping sheetrock for shiny/satin smooth paint. use a trouble light and hold it close to the wall/fender to find the dimples. It will create a shadow. Also using a different color primer over primer and then block sanding works great too. Remember to run the block sander in different directions when you sand. Diagonal is best. Somebody used to sell those flat stones that you use to clean grills. They are used for sanding bondo where you have a curved surface like a fender opening, where you want to sand it to match the existing metal. You sand on the metal and they wear down to fit the curve, so the bondo will follow it. Just running your hand over a panel will tell you a lot, 'til you get to the tiny ones.

 

A good way to find low spots is to lay a thin rag ( like an old CLEAN t-shirt ) underneath the palm of your hand and go over the surface gently. Try it! You'll be amazed at what you can feel!