[araljowder]

Hi all,

this is my first question here on the forum. I have encountered an issue with a water based polyurethane from italian brand and wanted to know if anyone had similar encounter.

Here is a little background about the project:

I built a twin MDF night stands, I sealed the case with a waterbased clear sealer from the same brand and dealer as per the dealer’s recommendations (2 coats sanding in between). Then I applied two coats of acrylic emulsion paint allowing about 6-8 hours dry time in between coats. Finally went with three coats of water based polyurethane in super flat (0% gloss) clear coat allowing 6-8 hours between coats.

As I was doing the final assembly two days after my final clear coat and my hands had a bit of lubricants from the drawer slides while handling the painted case, i went to cleaning the case from those oily finger prints with a wet shop towel only to find that my shop towel started forming a shiny spots on the towel while the texture on the rubbed part changed a bit. I was not aggressive with the rubbing or cleaning so i thought it was just some grease and oil which has been picked up by the shop towel or that the finish didnt cure fully.

As soon as i reached home i grabbed a test piece I made which was finished in the same manner above couple of weeks back to see if rubbing it with a wet towel would yield similar results, and it did. The texture on the finish did change slightly (not as much as the recently made night stand) and the paper towel had those shiny spots developing.

Not sure if this is specific to this brand of finish or sheen level (0% gloss) or that the finish has not cured fully. Anyone who had similar experience or uses a similar fashion of finishing can give an advice on what I could have done wrong here.

Thanks,

 

[Steve Neul]

To me it sounds like a defect in the final clear. The way a finish becomes flat is it has a flattening agent put in the finish. In dry form it looks like talcum powder which is added to a clear gloss finish. The more of this powder that is added to the finish the flatter it gets. The flattening agent rises to the surface and interrupts the sheen. I believe in your case it all came to the surface and when you cleaned it you removed the flattening agent which it shouldn't have done. I would recommend scuff it with a maroon scotchbrite pad and put another coat of a different brand of the same type clear over the top. First though since you may have oil on the surface, clean it with a wax and grease remover, even before scuffing it.

I think if you put another coat of the same brand clear on in time just normal handling it you will have shinny spots appear again.