Flaw detection

[ksechler]

All:

I'm going to be painting my 280z soon and had a few questions before I take that leap.

I have been doing a lot of blocking trying to get things just right.  The lighting in my garage kind of sucks and since most of the work is done in the evening it can make for a challenge.  I have several Halogen light stands and I put a fluorescent ceiling light in, but I'm worried I might miss some low spots and blemishes.  I've tried shining a light at low angles along the surface and have found some trouble spots, but I wondered if anyone here might have some other useful methods.

I bought some of the 3M dry guidecoat but I'm not sure I want to use it.  Here's my question about guidecoating:  Let's say you find a low spot where the guidecoat doesn't sand off.  Do you then have to remove all the guidecoat before you fill, and if so, how do you know where to fill, then??  

Thanks for any help.  

[sweatybetty]

46 minutes ago, ksechler said:

I bought some of the 3M dry guidecoat but I'm not sure I want to use it.  Here's my question about guidecoating:  Let's say you find a low spot where the guidecoat doesn't sand off.  Do you then have to remove all the guidecoat before you fill, and if so, how do you know where to fill, then??  

Thanks for any help.  

the short answer is no. leave the guidecoat, fill with whatever you are using and sand. repeat if necessary. also, buy yourself one of those el-cheapo 4 foot florescent lights that you can lay on the floor and move around as needed. they help a lot.

Edited May 10, 2016 by sweatybetty

[Patcon]

9 hours ago, sweatybetty said:

the short answer is no. leave the guidecoat, fill with whatever you are using and sand. repeat if necessary. also, buy yourself one of those el-cheapo 4 foot florescent lights that you can lay on the floor and move around as needed. they help a lot.

I agree...

Another method is to wet the panel down with wax and grease remover or lacquer thinner. The sheen it gives the panel helps find the flaws the way the shiny paint does...

[ksechler]

Thanks for the advice, guys.  It really is just trial and error isn't it?  

Pat, I've been using water to film the surface and look for flaws similar to what you suggest.  I accidentally discovered that technique while wet sanding.  I've also found that after blocking the primer with 600 grit it gets pretty shiny and I can look along the panels at a low angle for flaw detection.  The parts that are causing me the most stress right now are around my fender flares (compound curve) and the detail line that runs from the front fender, through the middle of the door and into the rear fender.  It'll be pretty obvious if that isn't straight!

Hoping to be able to spray the finish coat by Sunday but it might push into next week.  

[Patcon]

To get your side lines straight. Draw a straight line down the car with a level or some other straight edge using a pencil. Then run a piece of masking tape along the line either above of below. Block sand the panels up to the tape with out destroying the tape. When it's good, move the tape to the other side of the line and block sand again. when you're done the line will be nice and straight...

[sweatybetty]

12 hours ago, ksechler said:

Thanks for the advice, guys.  It really is just trial and error isn't it?  

Pat, I've been using water to film the surface and look for flaws similar to what you suggest.  I accidentally discovered that technique while wet sanding.  I've also found that after blocking the primer with 600 grit it gets pretty shiny and I can look along the panels at a low angle for flaw detection.  The parts that are causing me the most stress right now are around my fender flares (compound curve) and the detail line that runs from the front fender, through the middle of the door and into the rear fender.  It'll be pretty obvious if that isn't straight!

Hoping to be able to spray the finish coat by Sunday but it might push into next week.  

im going to throw in my 2 cents worth, gained from here http://www.autobody101.com/forums/  and from experience gained from just painting my car. SLOW DOWN! if you want it to look good SLOW DOWN. if you are just doing a flip, then by all means go for it. 600 is too smooth (IMO) for proper adhesion. do a little reading before spending a lot of money on paint. my 2 cents worth

[ksechler]

11 hours ago, sweatybetty said:

im going to throw in my 2 cents worth, gained from here http://www.autobody101.com/forums/  and from experience gained from just painting my car. SLOW DOWN! if you want it to look good SLOW DOWN. if you are just doing a flip, then by all means go for it. 600 is too smooth (IMO) for proper adhesion. do a little reading before spending a lot of money on paint. my 2 cents worth

I've been working on this car for 3 years.  I wouldn't describe my work as fast. ;-)

I spent 20 minutes last night blocking a 2 inch by 1 inch depression with 600 grit sandpaper.  Believe me, I'm going slow.

[sweatybetty]

sorry. it sounded like you just started.

[sweatybetty]

sorry. it sounded like you just started.

[ksechler]

2 hours ago, sweatybetty said:

sorry. it sounded like you just started.

No need to be sorry.  I appreciate any advice particularly as it pertains to slowing down and gaining a little perspective.  I've made some pretty big mistakes ignoring that advice. 

[siteunseen]

My Dad always said if I had to go 100 feet, I's spinning the first fifty then sliding the last fifty. 8^)

At 46 I still get excited and in a hurry but I'm getting better.

[Patcon]

@ksechler

Check the p-sheets for the products you're using. They will give you finish grits for each individual product. I very rarely finish above 400. I tend to agree with Sweaty, 600 starts to get really slick...