Do you wet sand with the 3m pad? Is it too abrasive? If so, do you put dish detergent with the water for lubricant?

@clinton By the way, when sanding sanding sealer, you don’t have to wet sand, I sand dry most of the time. It’s a product that sands very easily so using 320g dry is acceptable, it’s just a more dusty job without the water and detergent. The reason I dry sand is because if I sand through to the wood in places, I can just cover it again with the next round of sanding sealer being sprayed and it will be fine. If I am wet sanding and I sand through the sealer, the water will soak in and expand the wood in that area, it’s more difficult to fix. So just bear that in mind when deciding wet or dry. 
When it comes to sanding your topcoat, use wet but still be careful not to sand through. It’s tricky, especially finishing woods as they are all different and have varying grains to deal with. When I’m painting metals, it’s much easier as the surface is all consistent (or should be). The two different substrates do have their challenges from time to time but once you find the right system and gain enough knowledge of how to apply the right product and in which order, it becomes easier. 
Anyone can finish guitars or cars or bikes or trucks or furniture or just about anything if you have the patience to learn, especially from mistakes. 

Keep going man. 👍

It freakin worked! Did your advice on grain filling, opening the grain and sanding sealer step by step. Thank you thank you thank you. Finally my dilemna with swamp ash solved.

@clinton Nice one sir, you did it. I really like Ash, it’s a great wood to work with, even though it takes a little more work to fill the grain etc. Sealer is called sealer for a reason, it seals things in. I see it as a clear primer before the topcoat goes on. Obviously when you have a beautiful piece of wood with lovely grain, you naturally want to show it off, so you have to use the clear primer (sealer). 
It looks great my friend. 
Keep going. 👍 

Boo. 

I use the Avis brand, but I dunno if it's available outside of the Netherlands. I suspect any non-el cheapo brand will do. And yes, I mean white spirit.

@e-den-hertog That’s great, thanks very much for the info. 

Hope you are safe and well. 👍

It's extremely simple to make your own: 1 part quality polyurethane laquer (oil-based, not the water-based stuff...) and 1 part mineral spirits. Mix thoroughly.

@e-den-hertog Thanks for the reminder. Could you please give an example of a manufacturer of polyurethane lacquer please, maybe a link as well? 
Is mineral spirit, what we call in the UK, White Spirit?

Thanks. 👍

It's extremely simple to make your own: 1 part quality polyurethane laquer (oil-based, not the water-based stuff...) and 1 part mineral spirits. Mix thoroughly. Too thin? More laquer. Too thick? More mineral spirits. 

It's a great and super easy finish......

Do you wet sand with the 3m pad? Is it too abrasive? If so, do you put dish detergent with the water for lubricant?

@clinton I don’t normally use 3m pads, not with guitars anyway. Yes I do use a couple of drops of detergent in my water for lubricant. You don’t have to but it does help things move a bit easier and it makes the paper last longer. 

Posted by: @clinton

Have you ever used wipe on polyurethane? I want to attempt

No I haven’t and I really want to try it too. We can’t buy it here in the UK yet, although I do remember seeing one online UK store that has just got it in from USA. It really quite expensive for what it is, after paying the tax and delivery charge. If it becomes more widespread and cheaper, then I will definitely be having a go.