Water based finish problem

[Joseseat]

I'm trying to finish my tas oak dining table in cabots water based poly. I understand the concept of grain raise and I very lightly sanded after the first coat. A few coats in I can still feel roughness and when you look closely you can see raised fibres.

The top is old floorboards that I belt sanded quite heavily (80 grit) on a 45 degree angle to the grain, like a floor sander would do to achieve a level surface. I then went through the grades with the orbital sander before finishing. Maybe the belt sand was too harsh and tore up the fibres?

Can this be fixed by applying more coats of poly and eventually drowning this roughness or should I sand everything back and start again, which would mean staining again?

Did I not sand well enough initially? I sanded to 240.

[derekcohen]

Sand it back to bare wood.

Add 2 coats of shellac - I use Ubeaut White Shellac diluted 50% with meths. Give this a rub with grey mesh (400 grit).

Now wipe-on-and-rub-off your water-based poly. At least 5 coats. Alternately, spray it.

Regards from Perth

Derek

[ian]

I'm not sure what is going on, but agree with Derek -- sand back to bare wood and seal with shellac.

Given it's Tassie Oak, you may want to consider using a grain filler to fill the pores before applying the finish.

[Joseseat]

Thanks guys. More sanding

Not what I wanted to hear, but what I expected. Haha.

Does the shellac need to be lightly sanded between coats?

Shellac, light sand, shellac, light sand, WB poly...?

Also is there any point pre raising the grain by wiping with a wet rag before staining and subsequently shellacing? The stain is a feast Watson spirit based stain so it doesn't raise the grain itself.

[derekcohen]

You do not need to raise the grain bedore applying Shellac. It will not raise the grain either, or minimally, as it is alcohol-based. Still, I would rub (wipe) with grey mesh to denib it. I do this between coats of poly - each of which are very thin, but need the stray streak rubbed back. Note that the coats do build in thickness. It may not be apparent until the third coat. The water-based poly dries very rapidly. The next coat could be done after a few minutes.

Regards from Perth

Derek

[Joseseat]

Derek I was re-reading what you wrote earlier about wiping or spraying the poly, can any water based poly be wiped on? I normally use a brush? And by wipe on and rub off do you mean wipe on, let dry and then lightly rub off with the mesh?

Also what do you use to apply the shellac? Rag or brush?

Apologies for the thousand questions, I'm fairly green when it comes to finishing and I appreciate your responses greatly!

[derekcohen]

I apply the shellac with a rag - ideally a rag that has become saturated with the finish. Rub on and rub off. I try not to leave any marks behind. Imagine that you are polishing the surface of the wood.

I have experience with just one brand of water-based poly, but I suspect that they are all much of a muchness. I apply it exactly the same way as the shellac: rub on and rub off. A USA friend tried this recently, and applied it with a brush, and then rubbed the residue off with a saturated rag. That seemed to work as well.

Try it on a small section first.

Regards from Perth

Derek

[Joseseat]

Does rubbing off straight away not remove all of the material though?

[derekcohen]

It us thin, but enough finish remains to build on. That is why I recommend 5 coats. On the kitchen doors/drawers I have completed, the finish does not look thick and plastic. It is like a very fine spray. Just test it for yourself.

Regards from Perth

Derek