So this is around layer three of sealing. The back isn’t even glued yet. I’ve used Evo-Stik PVA from B&Q in a 50:50 water to PVA mix. Not sure if that’s right but I’ve read about a million (OK slight exaggeration) different guides advising that it’s wise to start with a heavy glue ratio to begin with as the devil’s foam (aka EVA) not only eats blades but drinks liquid like it’s going out of fashion. I’d say this needs at least another two layers before priming can begin.