Scuff Scratches Between Coats of Pre-Cat
From contributor J:
It sounds like the seal coat has completely cured, not allowing intercoat melt in. With any finish that cross-links, there is a certain amount of time before the cross linking has taken place, in which every coat will melt into the previous coat just like an NC lacquer.
When the seal coat has cross linked, the top coat lays on top of the seal coat, so the sanding scratches will not melt in and end up "telegraphing" through the top coat. Thinning the finish may make this worse, but I doubt it is the main cause.
This is more common with post cat CV than pre cat, but Magnamax cross links like CV, it just does it slower. It's the three week time span at work here. Another coat may or may not help hide them, depends on the color/viewing angle. 320 grit should be fine under normal conditions, but sandpaper varies and if the finish "corns" up on the paper, this can make deeper scratches.
From contributor R:
I agree with Contributor J. I just sprayed 33 shelves (cherry wood) with Magnamax. My first coat was Magnasand, followed by two coats of Magnamax Satin. I used 3M 220 Tri-mite sandpaper and 3M's Maroon scotch brite on the Magnasand prior to the first clear of Magnamax. Plenty of scratches were evident before my first topcoat. After the first topcoat, the shelves were like glass and without any sights of those scratches. Note that this was done within three hours of each coat. Naturally, my advice is to seal, sand and apply the first top coat within eight hours day.
From the original questioner:
Well I gave them one additional coat (this time scuffing with a finer synthetic pad instead of 320 grit) and the scratches have disappeared. I am very relieved to say the least but I think from now on I will be sure to allow enough time to finish things complete in one days time.
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