block sanding tank

[patooey]

hi all...i've done a few tanks and seem to get a a real faint wavy area on the top of the tank.(the flat area below the gas cap)....i'm interested to know if you folks block sand that area...or am i spraying wrong....thanks pa

 

[Bornhard]

I'm dealing with that same issue on a new sportster tank.
What I did was spray a couple coats of epoxy primer on and then shot a thin speckled guide coat of black over it. Let things dry (usually overnight) & then I would use a hard rubber sanding block, some 80 grit sandpaper and skim across the flatter areas of the tank. This will show you where your low spots are. I then fill in those areas with some basecoat clear coat putty. Sand that down, skim a thin coat of glazing putty over any sunken in areas and sand smooth. Next is a few more coats of epoxy primer to cover up your putty work & wait. DO the guide coat and block sanding again & you should be good to go or close to completion.

The tank I'm working on now I had to add a couple more coats of epoxy primer yesterday and today things were looking leveled. Sand that down real good and at this point I start to use those foam sanding block to work on the curves and edges of the tank. After I'm happy with my sanding I put a coat of Ko-Seal on and wait an hour or two to sand. I usually use some gray spray paint and mist it on for a guide coat on my sealer since the color of your sealer will be the foundation to your base coat color and you want the surface to be a solid color and not blotchy.

Make sense? 'cause I'm lost...??? /ubbthreads/images/graemlins/shrug.gif you might want to ask Rex about this....

 

[patooey]

thanks for some great information...i'll print this out and give this a shot....i've never guide coated the top and i'm sure thats my downfall...will do that now....thanks again...pa

 

[rex]

Yeah,try the guidecoat like Joe said,I've been doing bodywork over 20 years and still need to guidecoat sometimes.Besides using the standard rubber block that's about 4" long with the split edges and pins to hold the paper on I use 2 pads made by 3M or motorguard.One's called the Holy Terror that's pretty stiff and has one side smooth and one side with holes (they say the holey side is good for wetsanding out dirtnibs but I rarely use this side) and the other is a doublesided pad that's flexible and has a hard rubber side and a soft foam side.If you can block out a gastank and make it 'straight' you can block out anything,making something perfectly round or dealing with compound radiuses is not easy.

 

[Bornhard]

Yeah I use that hard rubber block for the flat areas of the tank and then get those FOAM sandpaper blocks from Home Depot, Lowe's etc. I usually DO NOT use the grit on the foam blocks , but wrap up the sandpaper you get from a jobber around those foam blocks. That way you can easily change your grit w/o having to buy every foam block they make.
Sanding the curves etc just takes a good eye to see that the shape is correct.

It can be a lengthly project, but it's just as important as the killer graphics on the bike.