Yeah, it’s ash? That’s almost always going to need a separate grain filling step for a completely flat final finish. I’ve found cherry, alder even Radiatia pine will fill with 2-3 coats of Createx Autoborne sealer then a sand back then another coat or two if I went through anywhere but I wouldn’t try that on ash or mahogany or something similar. The West Systems is going to come out for that. Leaving some of the grain works too though. I haven’t posted in my thread for a while but I’m working on that guitar and, since it’s too cold to spray here, I’m trying oil based wipe on polyurethane and it’s working nicely but the mahogany or mahogany like body and neck wood will definitely have grain showing.