Finishing Problem

Mark Johnson

Mark
Corporate Member
I made a really nice piece using walnut and wanted an oil look finish (satin) with some protection so used Watco oil. I followed the directions: flood coat and wipe off, flood coat and wipe off, and final coat. The sheen was horribly uneven so I assumed that the problem was the wood pores and added more oil. I never could get an even sheen. (everything was sanded to 220). So, I wiped hard with mineral spirits and coated with a seal coat of dewaxed shellac. This was not acceptable either, so I pulled out the sander and sanded back down through the shellac coat and into the oil coat. The sandpaper fouled quickly from the oil, but this was not unexpected. Then I wiped hard with mineral spirits again, and began applying clear wipe on poly. After probably 7 coats of wipe on I have an even high gloss sheen. HOWEVER, I want to get back to satin. What is the best way to do this without having to go back to reapply a finish? Steel wool ()000) is too coarse and scratch marks will most certainly show.
 

Jeff

Jeff
Corporate Member
An oil finish like Danish oil is "in the wood" because it penetrates the surface. It also has a satin sheen because of that penetration.

I never could get an even sheen. (everything was sanded to 220)
.

Sanding to 220 g is not necessary because the wood surface is burnished and prohibits the absorption of the oil and that's probably why your sheen was uneven.

What brand of wipe-on poly did your use? Was it gloss or satin sheen?
 

Mark Johnson

Mark
Corporate Member
I used minwax wipe on poly. Tried the satin sheen first and it was horrible (and yes I shook the can well first). It imparted streaks into the surface, so I sanded lightly and began putting on gloss poly until the sheen was uniform and the streaks were no longer visible. Poly applied with with a flat surface cotton rag and I was careful to cover all surfaces and wipe off any excess.
 

Henry W

HenryW
Senior User
I used minwax wipe on poly. Tried the satin sheen first and it was horrible (and yes I shook the can well first). It imparted streaks into the surface, so I sanded lightly and began putting on gloss poly until the sheen was uniform and the streaks were no longer visible. Poly applied with with a flat surface cotton rag and I was careful to cover all surfaces and wipe off any excess.
Mark I understand your (presumed) reluctance to go back to a product that gave you streaky results. But now you have a different situation - sealed wood now versus bare wood previously. Now that the gloss poly has sealed the surface and built up enough, changing the sheen is a matter of either:
A - adding a layer that has flatteners added to diffusely scatter the light (i.e. satin poly), or
B - scratching up the surface in a controlled way to diffusely scatter the light (rubbing out to control sheen).

Given that you already have satin poly, if I were you that is what I would do. It is of course possible that your product is somehow faulty for whatever reason and will give you streaky results no matter what.

If I were to choose route B, I would want to practice the method before using on a real piece, because this is more skill based than product based (although using the right product is important, I can't tell you what that is; brown paper bags are suggested above).

I do not have experience with method B, whereas I have used method A (the 'Satin topcoat over Gloss base layer polyurethane') to achieve decent results. In fact that is the methodology suggested by finishing experts for better optical clarity of an overall polyurethane finish (loading each layer of a multi-layer finish with the flatteners that make Satin less glossy than Gloss makes the overall finish have less clarity, or makes it look 'muddier').

Hope that helps, and let us know what you ultimately decide and how it works out.

Additional note - satin poly needs to be well stirred, and not shaken (opposite of a martini?); typically says this on the side of a can in fine print (which I struggle to read these days for some reason).
 

Charlie Buchanan

Charlie
Corporate Member
Just a note on steel wool. Ordinary big box steel wool in 0000 is useful for lots of things, but as you said it is pretty course for rubbing to break a gloss. Liberon brand 0000 is several grades finer and will break the gloss without noticeable scratches. Klingspor sells it and other woodworking suppliers. It comes in rolls and you cut off a short piece, wrap it around a felt block or cork block or other soft sanding block. Use one side then turn it over, wrap it around the block again and keep going. Use a strong back light so you can see the gloss go away and see any places you have missed.
 

ehpoole

Ethan
Corporate Member
You have several possibilities as outlined above. When it comes to finishes it is the final coat that will dictate the sheen depending upon the presence of or absence of flatterers (typically very fine silica) or scratches — you could do 3 costs of high gloss followed by a single coat of satin and your end result would still be a satin sheen because of that final satin coat.

The other option, as already mentioned, is to impart uniform scratches in the final coat to break up the light in the same way as the flatterers typically would in a non-gloss finish. You can use steel wool, artificial steel wool, or even automobile polish and a buffer to make those fine scratches (which works well if you can uniformly polish the area for an even texture with a random orbital polisher...or by hand). It’s also helpful to keep the surface wetted and constantly moving to keep everything cool as you don’t want the scratching or polishing to ever build up enough heat to damage the finish which is a plastic and can be damaged or distorted with excessive heating. You’ll want to first practice your intended protocol on a scrap piece of wood finished similarly to your existing project to find out if a particular approach will produce your desired finish

But the simplest solution is to simply apply a final coat of satin finish over what you already have. I suspect your streaking may well have been caused by uneven thickness in your wipe-on coat where some areas may have been overly thick and some overly thin, others just right. When using a wipe-on finish you may need a couple of coats as your final coat since they are so thin individually and such are not always of uniform thickness depending upon your wiping technique.
 

Stuart Kent

Stuart
Senior User
I would do one of two things:

1. lightly and evenly scuff the surface with green scotchbrite and topcoat with a good quality soft sheen wax like Black Bison or Briwax.

OR

2. sand entire surface evenly with 600 grit and topcoat with satin wipe on poly.
 

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