Does anyone have any advice about mixing products from different manufacturers? If I am out of PPG slow hardener, any harm in using High Teck? Assuming they are the same mix ratios? I realize the isocyanate ratio needs to be correct for it to cure properly and mixing brands may leave some unbound. But does this cause a problem in the real world or just on the chemistry white board. What about using a wet bed from House of Kolor and PPG Omni basecoat?

Its hard to photograph. Easier to see in person, although I know where to look. The color is a 1969 Ford OEM color "Black Jade". It is a dark green/black with metallic. The car suffered a chip on the edge of fender. I did a touch up spot repair using a glass fiber sanding pen, base coat with a needle/syringe followed by touch up clear coat with sanding/polishing. The touch up color was too dark and did not match. I sanded the repair back down and primed the now larger area. I got a small batch of paint mixed up at my jobber/auto paint supply store after they did a color match and spray out card. I base coated the primed area and finished with a drop coat. After appropriate flash time, I sprayed clear over the repair with blending solvent at the margins. I did not re-clear the whole fender. I now have a very subtle clear halo and the repair color is too light. I am guessing that I changed too many variables with the custom color and the drop coat. By doing both, I overcorrected the dark color. I have since done several spray out cards - with and without drop coats and various gun pressure settings to find the best match. Some recommend increased pressure for drop coat, others decreased pressure. As for the clear halo, I just learned the hard way why its hard to blend clear in certain locations without body lines to help you hide it. I plan on sanding the repair area, now even larger, back down - 400-600 grit? Scuff panel for adhesion with 800-1000/grey SB. Urethane sealer over repair with blending solvent applied at the edges with existing paint. Wet bed. Base coat the repair. Clear coat the whole panel. Anything I am missing? How would y'all approach this problem. How far down do I need to sand the repair and the clear halo. Do I need to take the entire area back down to metal? If so, is that because of a coverage/cover up issue or a too many mils thickness of the final product issue? I assume that the clear halo arises from the slight change in clear thickness at the edge of the repair... or is it something deeper in the clear layers? Could you theoretically scuff the clear and clear the whole panel to get rid of the halo? - I realize the problems this could lead to with adhesion, but I am just curious what the halo arises from.