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is this sanded far enough? (pics)

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Old 07-19-2011, 10:55 AM   #1
rithsleeper
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Default is this sanded far enough? (pics)

This is the door of my 89. Im seeing really tiny dots of my guide coat after sanding w/ 220. If I go to sand to a completely uniform grey, it starts going down to the white paint underneath... is this enough or do I have to get rid of absolutely all the guide. Before I do my next primer coat for a 320/400 grit sand.


Thanks for your help for all past present and future questions. Im getting there...

Last edited by rithsleeper; 07-19-2011 at 06:02 PM.
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Old 07-19-2011, 02:26 PM   #2
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I am just couple days sanding ahead of you, I think? I asked a similar question after one guide coat sanding with 220. I got some suggestions that I shouldn't stop there. But continue with atleast 400 grit. So following their advice I sprayed another coat of PPG
K-36 and guide coat and wet block sanded with the 400. It is so much smoother now it has a shine somewhat. I also sanded into isolated areas of the original color and will be shooting a final coat of primer/sealer PPG DP-50 then comes the base and clear coats.
Hopes this helps till more responses come along. Jim
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Old 07-19-2011, 06:00 PM   #3
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I wasn't clear about my question.

This is my second coat/sand of primer (equivilant to K-36). I intended to do a 3rd coat/ sand w/ 320 grit, and then a touch up/400 wet layer, then my 600 wet.

What I am saying is, once I get to the point I'm at now, do I have to keep sanding or should I stop and the next prime will fill the "dots" of guide coat. Every time I keep sanding till the guide is completely gone I hit original paint in places. I feel like this could be a never ending cycle if I keep sanding through...
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Old 07-19-2011, 07:52 PM   #4
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I guess I cannot answer that with any real experience. I am following an article written by Lars. It was found with the search function on this site. It describes the process step by step. Jim
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Old 07-19-2011, 08:50 PM   #5
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Sounds like you're not shooting very much primer? We used K36 on my '71 and didn't have your problem. Yes, we went through in some places, but just spotted those areas with more K36 and re-sanded and it came out.
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Old 07-19-2011, 09:43 PM   #6
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You may sand until all the guide coat is gone, OR until you see base material. If you cannot yet cut away all the guide without sanding through, you're not done yet. It is not straight until you can sand a single wet coat with guide and NOT cut through. Be patient, and get this step perfect, or I guarantee you'll be able to see the shortcuts through the topcoats. It is hard to be sooo close and not have it go easily... keep at it until it is correct. You'll be very happy you spent the extra time!
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Old 07-19-2011, 10:50 PM   #7
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I think from what im reading im not laying on the primer thick enough. The reason im hesitant to cover heavy is I keep getting this rough either dust or over spray on my panels if I don't spray one at a time then cover and spray the next. It takes me about 4 hours to spray the entire thing since I have to keep stopping and covering and uncovering, and then hanging each piece from the ceiling. My last prime I will lay it on at least 2 coats thick and hope my primer doesn't set up in my gun. Its really hot here in the deep south so my garage is over 90 sometimes 100 when I spray...
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Old 07-20-2011, 10:09 AM   #8
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Make sure you are using he high heat reducer for your primer. I am in the touch up phase of my primer coats and have used 400 paper. For some paint systems 600 may be too fine, just check your paint instructions. Good luck.

Last edited by Dave Tracy; 07-20-2011 at 10:10 AM. Reason: typo
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Old 07-20-2011, 09:26 PM   #9
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If you're getting dry spray/fuzzy overspray on adjacent panels I suspect you are missing something in your mixing and/or application rechnique. You don't specify what brand material you're spraying, or what gun/tip your applying it with.

Here's some generic suggestions assuming you are using a gravity HVLP gun with at least a 1.4 tip...are you measuring your primer/catalyst as you mix, or simply estimating the correct proportions? Do you have the liquid setting on your gun "wide open"? What air pressure are you using... again by guess or with a regulator and gauge? Dry overspray from too high air pressure might be an issue. Most (all??) primers can be reduced somewhat if your technique, or the temperature etc. require extended flow/flash times. I would explore thinning yours with a slow drying reducer. I can apply a coat of paint to my entire Corvette in about 10 minutes... if you are having your primer dry in the cup before you can get it on the car somrthing is really wrong, even with temps like the 104 after lunch here in Savannah today.
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