sanding sequrnce

[Ron H]

Howdy, I finally primed a flat surface on my fifty seven. So far i've been in inconsequential areas, trunk etc. Now I need to know what sequence of grit to use when sanding. Maybe this would be a good subject to include in the basics section? Thanks Ron

[Len]

The grit primer is sanded with is usually dependent upon how level the surface is and how many coats of filler primer is going to be needed to level it. If more than one coat is needed we will usually sand the first coat (or two) with 220 or 320 wet but when we are sanding the final coat, that will be painted with our topcoat, we will finish the sanding with a grit between 400 and 600 wet.

The grit for the final coat will depend on the top coat materials that we intend to apply. A solid color will can usually have a primer sanded with a more coarse grit like 400 wet while a base/clear metallic is usually sanded with 500 or 600 wet.

If you sand dry you can usually get away with a slightly lower number like 400 for metallic because the dry paper doesn't cut as deep.

Also always us a "guide coat" in order to get the surface perfect. Use dry guide coat for dry sanding and spray-on guide coat for wet sanding.



SEM Aerosol Guide Coat Link (http://autobodystore.net/Merchant2/merchant.mvc?Screen=PROD&Product_Code=SEM38203&Category_Code=PSH)
http://autobodystore.net/Merchant2/graphics/00000001/sem38203.jpg

[don]

Len, I am having my car painted with acrylic urathane single stage this week. The shop said I should sand with 600, but the PPG sheet recommends 400. I am using 400 wet tonight for the first time and am finding it somewhat tricky using an 10 inch rigid block. Any advice? Thanks Don.

[Jon E]

Howdy, I finally primed a flat surface on my fifty seven. So far i've been in inconsequential areas, trunk etc. Now I need to know what sequence of grit to use when sanding. Maybe this would be a good subject to include in the basics section? Thanks Ron

Ron,

If you're blocking to get the surface straight, start with 80 grit on a long block and keep blocking and repriming it until its absolutely perfectly flat, then step up to 180 to finish the detail work. The last time I block it with 180, I usually blow it off, spray it with a guide coat, then wet sand it with 500.