# Desperately Need Help On Polyurethane Mirror Finish!



## user9609 (Jul 27, 2009)

Hello everyone. I am in desperate need of help with finishing a project of mine. I am trying to get a mirror polyurethane finish, but no matter what I do I continue to have problems. My biggest issue is that once I rub out and polish my project, it becomes very glossy, but I can see what looks like smudges and milky white streaks under the finish. I can even rub my finger across the finish and some of the streaks start to gum up and roll off my project.

I have tried wetsanding the finish down and starting the polishing process over again, yet the same thing continues to happen. For the record I started out with Minwax Brush-On Polyurethane and then decided to go with Spray-On. I wetsanded the final coat the next day and then I let it sit for 2 weeks before rubbing out/polishing it (it has been humid here the last few weeks if that helps at all). For the wetsand I started with 800 grit and finished at 2000 grit and for the polish I used 3M Rubbing Compound, and Meguires Swirl Mark Remover.

Everything looks good until I begin the polishing process, what the heck am I doing wrong guys? Thanks in advance for any and all advice given!


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## Chad (May 10, 2009)

It sounds to me like if your using a buffer your heating of the finish a little. If you are using a buffer , lesson up on the pressure a little let the compound do the work. Also keep the compound and swirl remover damp (as in don't buff till it's dry). Wipe lightly with a soft cloth the residue. That's what I used to do when I painted cars. Different materails but same principle. Hope I helped


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## user9609 (Jul 27, 2009)

Chad said:


> It sounds to me like if your using a buffer your heating of the finish a little. If you are using a buffer , lesson up on the pressure a little let the compound do the work. Also keep the compound and swirl remover damp (as in don't buff till it's dry). Wipe lightly with a soft cloth the residue. That's what I used to do when I painted cars. Different materails but same principle. Hope I helped


Thanks for the reply. Actually I'm not using a buffer at all, everything is being done by hand, do you have any ideas what else it could be? Maybe I was rubbing too hard? but I don't feel like I was, I was going pretty light.


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## cabinetman (Jul 5, 2007)

Is it oil base or water base?


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## user9609 (Jul 27, 2009)

cabinetman said:


> Is it oil base or water base?


Sorry about that. It is oil-based.


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## cabinetman (Jul 5, 2007)

My guess is that the coats you applied didn't cure. Oil base polyurethane doesn't "meld" into the previous coat, and will delay that coat from curing. Brushing it on will leave a fairly heavy coat that may take quite a bit of time to "cure" completely.

If you can get a gummy layer from the surface that's likely the cause. Once completely cured, oil base polyurethane should wet sand and rub out nicely.


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## user9609 (Jul 27, 2009)

cabinetman said:


> My guess is that the coats you applied didn't cure. Oil base polyurethane doesn't "meld" into the previous coat, and will delay that coat from curing. Brushing it on will leave a fairly heavy coat that may take quite a bit of time to "cure" completely.
> 
> If you can get a gummy layer from the surface that's likely the cause. Once completely cured, oil base polyurethane should wet sand and rub out nicely.


Ahhh, that may be what it is then. Your comment about the poly not "melding" into the previous layer makes sense, since I went spray on top of wipe-on. What do you recommend? I was just going to wetsand the things down again, re-spray, re-wetsand and maybe give them a longer curing time this go-round? What are your thoughts? Also, should I wait until the poly cures to wetsand or should I do it after a few days and then let it cure to polish? Thanks again for your help.


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## cabinetman (Jul 5, 2007)

ab76 said:


> Ahhh, that may be what it is then. Your comment about the poly not "melding" into the previous layer makes sense, since I went spray on top of wipe-on. What do you recommend? I was just going to wetsand the things down again, re-spray, re-wetsand and maybe give them a longer curing time this go-round? What are your thoughts? Also, should I wait until the poly cures to wetsand or should I do it after a few days and then let it cure to polish? Thanks again for your help.



Well, I don't know how thick you already have it. In lieu of stripping it and starting over, try letting it really cure. Then try wet sanding. Then if it needs another topcoat, do a light one. Then let it "cure". Your final sanding should not be gummy. You can't rush this stuff.

If dry sandpaper seems to stick somewhat, that's one clue it hasn't cured. Once you get into the topcoat is where you'll find out. Your fingernail shouldn't make a nick.

These cabinets are done with a rubbed out oil base polyurethane:
.


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## user9609 (Jul 27, 2009)

cabinetman said:


> Well, I don't know how thick you already have it. In lieu of stripping it and starting over, try letting it really cure. Then try wet sanding. Then if it needs another topcoat, do a light one. Then let it "cure". Your final sanding should not be gummy. You can't rush this stuff.
> 
> If dry sandpaper seems to stick somewhat, that's one clue it hasn't cured. Once you get into the topcoat is where you'll find out. Your fingernail shouldn't make a nick.
> 
> ...


WOW! Those look awesome. I think I may just do the process over again as I already have one side wetsanded down and I don't know if there is enough poly to build it back up. My project wasn't gummy during the wetsand though only during the polishing, but it still seems like it wasn't cured properly (especially with the humidity out here). I am just going to have to give it more time this go-round and maybe let them cure in the basement where it's cool.

Thanks for your help. If you have any more tips for me please feel free to chime in!


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## Rick Mosher (Feb 26, 2009)

Catalyzed finishes work best for buffing because they cure faster and can be buffed sooner for production purposes. If I have to do a high gloss finish with an oil based product I would use Behlens rock-hard table top varnish. The danger of doing low build coats on a buffed finish is the danger of going through a layer and getting the dreaded "halo" which can only be fixed by sanding, spraying another coat and trying again. For even results you will probably want to go with a buffer, use a slower speed and a lambs wool pad. (The foam pads will heat up too much for your application) I hope this helps.


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## user9609 (Jul 27, 2009)

Rick Mosher said:


> Catalyzed finishes work best for buffing because they cure faster and can be buffed sooner for production purposes. If I have to do a high gloss finish with an oil based product I would use Behlens rock-hard table top varnish. The danger of doing low build coats on a buffed finish is the danger of going through a layer and getting the dreaded "halo" which can only be fixed by sanding, spraying another coat and trying again. For even results you will probably want to go with a buffer, use a slower speed and a lambs wool pad. (The foam pads will heat up too much for your application) I hope this helps.


Hey thanks for the tip. How resistant to water/moisture and wear is that varnish and how difficult is it to apply? I take it it has a much lower cure time than polyurethane does? I may go down this road if it is a durable solution that will get me the results I am seeking.


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## Rick Mosher (Feb 26, 2009)

Here is the spec sheet: They say 72 to 96 hours before rubbing. That's pretty good for an oil based varnish.



H. Behlen
*A Division of RPM Wood Finishes Group, Inc.*​ ​ *Product Data Sheet*​ ​ *Rockhard Table Top Varnish*

*B603-2850*

Available in pints, quarts and gallons

*Product Description:* Rockhard Table Top Varnish is a quality phenolic resin “short” oil varnish, amber in color; which develops a hard, solvent resistant, gloss finish. Sets to dust free in about 4 hours, dry to handle in 12 hours. Recoat in 12 hours, Rockhard Table Top Varnish is designed for interior use only. 


*Characteristics:*
Weight per gallon: 7.39 lbs/gal
Solids % (wt): 54.00
Solids % (vol): 48.00
Dry time: Air dry @ 72º F, 35% relative humidity
Dust free: 4 hours
To handle and recoat: 12 hours
VOC’s (coating): 3.39 lbs/gal (407.49 g/l)
VOC’s (material): 3.39 lbs/gal (407.49 g/l)
VHAP’s: 0.0 lbs VHAP’s/lbs solids
Coverage: 769 square ft/gal @ 1 mil thickness
Package Life: 3 years

HMIS: Health – 1, Flammability – 2, Reactivity – 0, Personal Protection – X 

*Specifications:*

Directions: 

*Wood Preparation*: Finish sand wood with 120-150 grit sandpaper and remove sanding dust. Stain raw wood with Behlen Solar-Lux Stain or pigmented 15 Minute Wiping Stain. Allow required drying time for each type of stain. Open grain wood may be filled with Behlen Pore-O-Pac or Water Base Grain Filler. For natural finish, Rockhard Table Top Varnish may be applied directly to the bare wood.
*Mixing Directions*: Mix thoroughly by stirring; do not shake as vigorous shaking would incorporate air bubbles, which could become trapped in the dried film. Rockhard Table Top Varnish is supplied at brushing consistency. As a seal coat Rockhard Table Top Varnish should be reduced 1 to 1 with Rockhard Table Top Varnish Reducer, other coats may be applied at full strength (for better flow may be reduced up to 25 %).
*Application*: It is recommended that a good natural bristle brush be used for Rockhard Table Top Varnish. Best results are obtained when thin uniform coats are applied across the grain of the wood, brushed level with the grain. Scuff sand with 320 or 360 grit paper between coats. One quart covers approximately 125 sq. ft.
*Rubbing*: Depending on drying conditions and the thickness of finish applied, allow at least 72 to 96 hours drying time before rubbing wet or dry. Allow an additional 24 hours drying time before use.
*Clean Up*: Use mineral spirits or Rockhard Table Top Varnish Reducer. 

*Safety Cautions*: 

Risk Phrases: Vapor harmful. May affect the brain or nervous system causing dizziness, headache or nausea. Causes eye, skin, nose and throat irritation. May cause allergic skin reaction. Non-Photochemically reactive.

*Contents: petroleum distillates & di-petene.*


Notice: Reports have associated repeated and prolonged occupational overexposure to solvents with permanent brain and nervous system damage. Intentional misuse by deliberately concentrating and inhaling the contents may be harmful or fatal. Keep away from heat and flame. Prevent buildup of vapors by opening all windows and doors to achieve cross-ventilation. Use only with adequate ventilation. Do not breathe vapors or spray mist. Ensure fresh air entry during application and drying. If you experience eye watering, headache or dizziness, or if air monitoring demonstrates vapor/mist levels are above applicable limits, wear an appropriate, properly fitted respirator (NIOSH/MSHA approved) during and after application. Follow respirator manufacturer’s directions for respirator use. Close container after each use. Avoid contact with eyes, skin and clothing. Wash thoroughly after handling. 

First Aid Measures: If you experience difficulty in breathing, leave the area to obtain fresh air. If continued difficulty is experienced get medical assistance immediately. In case of eye contact, flush immediately with plenty of water for at least 15 minutes and get medical attention: for skin, wash thoroughly with soap and water. If swallowed, get medical attention immediately. If spilled, contain spilled material and remove with inert absorbent. Dispose of contaminated absorbent container and unused contents in accordance with local, state, and federal regulations.

Keep out of reach of children.

See Material Safety Data Sheet (MSDS) for complete information and first aid.

*MSDS:* If Material Safety Data Sheet is required, contact:
H. Behlen
Division of RPM Wood Finishes Group, Inc.
P O Box 22000
Hickory, NC 28603

Phone: 1-866-785-7781
Fax: 1-800-721-1545


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