# Dulling a glossy polyurethane finish...



## Picturemeister (Nov 22, 2012)

How can I CHEMICALLY dull a polyurethane finishing I've applied to an art project?

The "satin" finish is far too shiny for my needs... and would like to brush on something to uniformly dull it.

*I of course know about using steel wool to PHYSICALLY dull the finish, however this sculpture has deep recessed
areas that are NOT accessible for physically abraiding. --- Any suggestions on some sort of CHEMICAL treatment, such
as a mild acid (vinegar?)(alcohol?) or product that could brushed onto the deep complex surface and then wiped off?

My thanks!


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## Rick Mosher (Feb 26, 2009)

I would scuff sand the entire surface and apply a coat of dead flat polyurethane. You didn't specify whether you used water or oil base but just stick with the same base you used originally. The dead flat will dry completely flat (no sheen) and then if wanted you can lightly polish the high spots to create a natural looking patina.


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## Picturemeister (Nov 22, 2012)

Thanks for your thoughts Rick...
"Scuffing the surface of this bas-relief sculpture is easy enough via steel wool, however, the real challenge is to knock down the the deep recessed (and often intricate) areas that have the glossy sheen (that even the "satin" polyurethane imparted). --- This is why I thought a more chemical approach would be best to uniformly flatten ALL the 'peaks & valleys' of the surface. I could do some tests with mild acids, such as vinegar or diluted Muriatic acid... but I fear that IF they flattened the sheen, they might likewise cause it to frost (get a milky non-transparent quality).

You mentioned re-coating with a "DEAD FLAT polyurethane", which is an interesting idea. I've never seen such a product... it is certainly NOT available @ Home Depot or Lowes. Satin is the lowest gloss product they (and most paint stores) carry. 
A question or two about this "dead flat" poly. :

1. Is this an actual product name, or just an adjective?
2. Where can a fellow buy such a thoroughly FLAT product??

My thanks for any assistance.


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## Steve Neul (Sep 2, 2011)

Picturemeister said:


> Thanks for your thoughts Rick...
> "Scuffing the surface of this bas-relief sculpture is easy enough via steel wool, however, the real challenge is to knock down the the deep recessed (and often intricate) areas that have the glossy sheen (that even the "satin" polyurethane imparted). --- This is why I thought a more chemical approach would be best to uniformly flatten ALL the 'peaks & valleys' of the surface. I could do some tests with mild acids, such as vinegar or diluted Muriatic acid... but I fear that IF they flattened the sheen, they might likewise cause it to frost (get a milky non-transparent quality).
> 
> You mentioned re-coating with a "DEAD FLAT polyurethane", which is an interesting idea. I've never seen such a product... it is certainly NOT available @ Home Depot or Lowes. Satin is the lowest gloss product they (and most paint stores) carry.
> ...


I agree with Rick’s suggestion to apply a flat poly to solve your problem. Anything you might put on the existing finish to dull it would damage the finish. The only other option would be to rub the finish which will make the appearance cloudy. All polyurethane with the exception of gloss has a flattening agent added to it to interrupt the sheen. The more flattening agent it has determines the difference from semi-gloss to satin to flat. You will have to go to a regular paint store for a flat poly. The box stores are only going to sell the most common products. It is also possible even a paint store won't stock the flat poly but will order it for you. It would be better to use a prepackaged flat poly but if that isn't a option a paint store can sell you the flattening agent to add to satin poly to flatten it more.


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## cabinetman (Jul 5, 2007)

Picturemeister said:


> I could do some tests with mild acids, such as vinegar or diluted Muriatic acid... but I fear that IF they flattened the sheen, they might likewise cause it to frost (get a milky non-transparent quality).


You didn't state whether it was an oil base or waterbase polyurethane. I wouldn't go experimenting with acids, as that can be hazardous. An old time fix was to add talc (baby powder) to a low gloss. I haven't done testing on the results to see if the mix will impair the finish over an extended period of time.

There are additives for both oil base, and waterbase...
http://www.harmonyadditive.com/additive.html










 







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## Da Aardvark (Oct 11, 2012)

Some satin/flat polies unless mixed thoroughly (the satin/flat sediment will sink to the bottom of the can) and if not put on in optimum temperatures will dry slower (slow, cold temp drying shines things up.) and produce a shine.
Only way is to re-apply in optimum conditions or scuff it. I use #0000 steel wool. Many here might say it leaves particles that will rust (never seen it on my stuff). Steel will will get down into crevices. If that is too dull, you can start polishing it back up with a slurry of pumice or rotten stone and actually polish it up to a hi-gloss.


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## Rick Mosher (Feb 26, 2009)

I didn't suggest a product because I didn't know if you used oil or WB poly. Modern Masters makes a WB dead flat polyurethane and Epifanes makes an oil based matte varnish. 

The surface must be scuffed before application of another coat to assure adhesion. Otherwise the newest layer of varnish could peel off. You don't have to scuff in every nook and cranny though as the deep areas are unlikely to be touched to cause a problem.


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## Picturemeister (Nov 22, 2012)

My thanks to all of you for your feedback (p.s. I'm using an oil based poly).

I'll explore the flat poly's recommended (thanks for their names/label info).... In summary here are a few things I learned:

- Important to stir well to thoroughly mix flattening agents prior to appl.
- Apply in warm (not cold) room
- I might explore adding talc, or purchase flattening agent from paint store.


To those still recommending steel wool, trust me, it is not an option in this case as recessed intricate areas are up to 1 1/2" deep, just NO way to work steel wool into those "shiny" areas. (this is sculpture, not furniture) - Must be a chemical solution here.
Again my thanks for all the great suggestions.


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## Da Aardvark (Oct 11, 2012)

Some say cornstarch will flatten when mixed in.
I won't suggest it since I haven't tried it.


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## cabinetman (Jul 5, 2007)

Can you post a picture of what you are working on...sounds interesting.









 







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