Wet sanding using 1200 grit on my brown table has created a white/dust-like cover

Question

I worked on 2 projects for painting a wood table and a metal table, where wet sanding had worked perfectly on the metal table while it ruin the wood table, as follow:-

1. I have a wood table which i painted using oil-based semi-gloss Jotun brown paint around 3 months ago. where there were many paint brush strokes.. so i decided to do a wet sanding for the table. i used 1200 grit sand paper + water. after wet sanding the table i cleaned the surface, but the sanding has created a white/dust-like surface, which will not go even if i use soap to clean the table for many times.

2. while on my second project, i have a metal table which i painted using Dulux oil-based satinwood white paint around 3 days ago. where there were many paint brush strokes.. so i decided to do a wet sanding for the table. i used 1200 grit sand paper + water. after wet sanding the table i cleaned the surface, and the surface had a glass-like finish and most of the paint brush strokes disappeared, which is what i were looking for.

so can anyone advice why the wet sanding worked on my white metal table and failed on my brown wood table? is it because wet sanding dark colors will not work? or because i wet sanded the wood table after 3 months of painting it unlike the metal table while i have painted only 3 days ago? Thanks.

Here is a picture of the failed project:-

Answer 1

I suspect the reason for the different outcomes is a result of using two different types of paint. The different properties and composition probably means their surface will respond differently to being sanded.

Many glossy surfaces will be dulled by sanding, even at 1200 grit. You were fortunate with the white table. Perhaps it doesn’t show the effect up as much because it is already white.

Sanding is an appropriate method to remove brush marks from a painted surface, but not as a final finish. It should be used as a preparation step before repainting.

Whatever the cause, you’ve not ruined your table, you just need to sand it correctly and repaint using a better technique.

The paint on your white table might now have an ‘open’ surface with micro abrasions from the 1200 grit. This could make it more susceptible to dirt or stains and it might need refinishing at some point.

For your brown table, you can prepare the surface ready for repainting and try again.

• Dry sand with something like 120 to remove any remaining brush strokes and unevenness, followed by 180 to remove any scratches from the 120. Either way you need to rough up the surface a little because 1200 is too slick for the new paint to bond to properly. You could sand back to the original wood, or just stop when you get a nice even surface to repaint.
• You could repaint using aerosol spray paint, which should give an even finish. Follow the instructions carefully especially about ambient temperature, distance, using several light coats and don’t put too much on at once so it runs.
• You could try again with an oil based paint, but apply with a mini roller and a disposable short pile sleeve, followed by very light laying off with the tips of good quality brush to remove the roller stipples. Work quickly before the paint starts to skin over.
• You could try again with a good quality brush. Work quickly and don’t overbrush the paint.

Personally I found that oil based gloss was easiest to paint to a flawless finish, followed by oil based satin and then water based needing the most skill.

Some tips here on getting a good finish: https://traditionalpainter.com/flawless-paint-finish

Answer 2

You have just muddled and mashed the glossy layer of your finish. The dampness even made it worse because while sanding there was probably some light discoloring.

But when sanding wood with a gloss finish you have to sand all the way down before the "white" cover disappears. You could get the same finish and whiteness using a rough grit dry and lightly sanding. Like I said you muddled it up but you have really not damaged anything.

What you need to do if sand it down and then redo it...

However compare this table to oak hardwood floors in a house. If I do NOT have a glossy layer (poly on floors), I can pretty much sand any where I want and restain carefully. Adding the element of poly makes it almost impossible to take a small bit of the floor and only redo that. Yea you can but it is really hard and usually still noticeable. Many companies that refinish will recommend at least do a room.

So with your table you are much better off hitting it with a high grit sand paper on the top and working your way down and redoing the entire top. It will be very very difficult to patch a circle in the middle (which is much easier on metal) and even after doing a really good job you may still notice.

Answer 3

It's hard to see from your photo, but I believe I can make out what appears to be the lightened surface you said became white. It's not a clear photo, BUT what I can decipher is simply a painted surface that became lighter in tone because it was sanded. I can't respond about the dust that can't be removed you mention. I don't believe water played a part(unless it's high mineral deposits).Doubtful though. Sanding abrasive from wet/dry paper, a paint binder reacting to the water,etc??? What you should do is wipe your hand across the surface and see if there is any chalking or dust. If not reapply paint with a foam roller or brush to eliminate brush strokes. Also you can use a paint additive that will increase the open time (drying time) to allow the brush strokes to level-out and be less noticeable. Let the paint dry for several days than rub with a damp sponge. If no paint peels away you should be good.

Answer 4

1200 grit on any painted or coated wood surface is just too fine. Way too fine. The dust and debris generated can get into softwoods and mar, streak, and leave difficult blemishes. Hardwoods like oak, mahogany, rosewoods, hickory, have dense surfaces avoiding such problems. A XXXX steel wool rubdown, well cleaned, then a coat of Tung oil leaves a great polished surface .