A Smooth Finish for Cabinet Interiors

Tips and techniques for eliminating surface roughness in water-based finishes for cabinet interiors. April 30, 2006

Question
I am spraying General Finishes PolyAcrylic semi-gloss over oak with a Devilbiss finish line HVLP air spray gun and am having problems getting a smooth finish. I spray two coats followed by a light sanding with 400 grit, then I spray a final coat. The final coat looks good but feels a little rough. Can the last coat be polished out with something or do I need to change my technique?

Forum Responses
(Finishing Forum)
From contributor A:
My suggestion would be to try a more thorough sanding on the first sealcoat with 220 or 280 grit.



From Paul Snyder, Finishing Forum Technical Advisor:
Is the surface smooth as silk after you sand? Do you allow enough time between coats and before sanding (see the data sheet)? How wet do you spray the final coat? What exactly does "a little rough" feel like? Overspray? Dry spray? Orange peel?


From the original questioner:
Thanks for the replies. After I sand, the surface is smooth - I don't feel any raised grain. I waited around an hour after the second coat before sanding. The final coat goes on fairly wet - I try to find that point between just enough and too heavy, where it runs. The final surface feels like overspray although everything is wet and glossy when I place the parts to dry.

I warmed the material up prior to spraying and slightly thinned it down some. I can't run my vent fan because it would cool the shop down to much but the drying parts were placed several feet away from the spray area. Overspray in the air was slight. Do you think that was the problem?

I was spraying cabinets insides with the backs removed. I spray the deck and top first, overlapping the sides about six inches -turning the box so that the surface that I am spraying is horizontal - then I spray the sides beginning and ending at the six inch overlap to avoid buildup in the corners.



From contributor B:
It's pretty hard to avoid some overspray when coating the insides of cabinet boxes. I'd rub them out a little with the gray 3m pads to give a smooth touch. 320 grit sanding sponges are pretty quick too and get a similar sheen. They don't last too long though so stock up. Used 180 grit sponges are also good.


From contributor C:
Try 240, 280 after first coat, and 600 after second coat. Check what the min/max temps should be for spraying. Filter everything well. How do you deal with your sanding dust? No traditional tack cloths for WB sprays - maybe itís this prep that is at fault.

We also found that the downside surfaces seem to finish a bit rough, so now we spray all our boxes upside down. Vertical parts always seem to finish out fine no matter the overspray from each box.



From contributor D:
1. The slight overspray is a problem if you can't account for where itís landing.
2. I really urge you to consider prefinishing as many cabinets as you can prior to assembly. Our experience with waterbornes is that they feel really smooth when you lay on 3-5 wet mils. You get a faster build with no runs and in the end the handling is a lot easier.
3. If you aren't too worried about the appearance of the cabinet interiors but want them to feel smooth then by all means scuff the rough parts. We've found grey Scotchbrite works well, although it won't level the surface. Think through at this point if you wouldn't rather just prefinish everything horizontally!
4. Many waterbornes respond well to infra-red radiation. Prime Heat would be nice but if you can't afford it then I suggest getting a 220V 1ph, 30A IR ceiling mount lamp from Grainger's (less than $100?). After the 5 mil wet coat loses its glossiness set it under the lamp for a couple of minutes (depending on the distance, of course) to bring the surface temp up to 120 degrees for about 2 minutes. After it cools you can sand and recoat. Also nice for making samples!
5. If you are going to spray vertical cab interiors with waterbornes try a high viscosity coating - it may work for you.


From the original questioner:
Thanks for the replies. You have given me several good ideas to try. I sent an e-mail to Target Coatings - I think I will give their products a try. I used Varathane oil based stain under the GF Polyacrylic and am disappointed in the look so I need to spend some time and money learning to produce a better finish.