My experience says that is not a good way to cure the problem. When applying any filler you use a very flexible stopping knife (one where you've rounded off the outside corners on a stone, or even the back step - plastic spatulas, whilst somewhat less flexible, are less likelyvm to mar the work) and you always apply the
very minimum so that it doesn't spread all over the work
and into the grain as has happened here. If needs be an area to be filled can be stopped, sanded, stopped again and sanded again and so on to build-up filler. The OP has seemingly put great big gobs of filler onto the surface and spread it, then not sanded it back sufficiently. The filler is also the wrong colour - just because it says it is medium oak on the tin doesn't mean that the wood from the tree will comply. As a natural material wood tends to vary a lot in shade, so it may be necessary to mix 2 or 3 colours to get something approaching a reasonable match, but even that doesn't work completely because all finishes get absorbed into bare wood and change its' colour ,(mostly darken it) - whilst they don't get absorbed into filler (or for that matter sawdust and PVA, which is why that is a inadvisable, too) and they will generally stand out like a sore thumb unless you either tint it in afterwards (e.g. with something like Konig tinting pens) or mix the filler to be slightly darker and the correct tone (and sometimes more yellow or more red) in the first case. Without extra work filling is always a bit of a hit and miss approach
Whilst it goes without saying that as far as possible joints in clear finish work should always be as tight as possible (to reduce the amount of filling required), some filling is inevitable. A better approach, therefore, is
NOT TO FILL before finishing the material, but to apply the lacquer
first then go over small areas to be filled with a coloured repair wax such as
Liberon or
Konig. In my experience a light to medium oak may require wax sticks in light oak, medium oak, Jacobean oak (dark, to mix for knots), walnut (also for knots), mahogany (if any pinkish tinging is required) due to colour and tone variations and it may be necessary to have axdditional colours such as light pine or maybe antique pine (if a more yellowish hue is required).
You don't just rub the wax against the area where the filler is required - instead you warm up the waxes gently (I generally use a mug of hot water), scrape off some flakes of wax and roll them into a small ball (a few millimetres across) between your fingers. Add extra colours as required to get nearer to the colour needed, but always aim for a colour which is slightly darker (because oak will go more golden and darken with age AND a stopping which is a little too dark will be less obvious than one which is too light). The warmed wax is pressed into the crack or gap with the stopping knife, taking care to reduce the amount of spread to the bare minimum, and left to harden for a few minutes. Then the excess is removed by the stopping knife (for re-use) and the area burnished with a coarse cloth.
Where dowels or plugs (over screws) are used there are often a different colour to the surrounding wood (lower dowel):
The only way to deal with this is to tint in either with a water-based stain (weakened, built-up with several coats) or by judicious use of the
tinted touch-up paints. In the photo above the use of an inappropriate colour of filler (and over filling) is very obvious - the filler is lighter than the oak and possibly a bit too red. Doingbthis the dowel will still be visible, but should be less obvious
With open pore hardwoods such as ash and oak it is essential to understand that
any filler will sink into the grain and be hugely visible when the finish is applied, hence the need for caution. Sawdust and PVA are a terrible solution on visible at eye level work, in part because they tend to get everywhere but also for the reasons stated above. They get used on floors (although even there there are many better solutions), but a floor is almost always 5ft or more away from the viewing point (your eyes) and in any case people tend not to look at floors, whereas finished woodwork is a lot nearer to eye level and defects are a lot more noticeable. That is why a better technique is needed
How do i make good of what i have? Go over it with another filler or sand it out? Ive just seen a Ronseal oak coloured filler.
Gently sand-out the over filled areas with a relarively coarse sandpaper (P100 or P80) then refill or tint in depending on the defect (see above). Did the oak come pre-lacquered? If so a repair lacquer may be required to match the same sheen as the original (see Konig, again)
I've had some success in the past by painting white powder filler with artist's watercolour paint mixed to match the wood colour, then clear varnish on top. Needs a test run on scrap wood first, as the painted filler tends to darken a bit when varnished.
That's akin to the traditional technique in which ground whiting or plaster of Paris is mixed with water-based wood dyes and used to fill grain before finishing the timber. The only problem about using any water-based colouring agent is that they tend not to be light fast unless protected by a UV resisting lacquer
