3

I'm relatively new to woodworking. I just finished some desktops made from Eastern White Pine, and coated with 5-7 coats of post-catalyzed acrylic lacquer (Target Coatings EM-6000 + CL-1000) sprayed from a cheap HVLP sprayer. After a week of cure time I used a series of Mirka Abralon silicon carbide Sanding Pads (grits 1000, 2000, 3000, 4000) soaked in soapy water, 3-4 slow passes over the entire top. Then finished with Menzerna SF3500 using a foam finishing pad. The resultant finish has a very nice glossy shine, but it also looks very orange peel.

After seeing this on my first project, I thought that this just meant that I needed to be more aggressive with my initial sanding. So on my second desk I started with a 500 grit sanding pad before moving to the 1000, and I took a little more time than I did with the others. I was surprised to see that the second project looked as orangy, if not more so, than the first. Leaving me to wonder what's causing this and what step I'm missing in my finishing process.

I've never read of anyone needing to go rougher than 500 grit when rubbing out lacquer. What's the proper way to deal with this? Why (physically) does this happen? Do I just need to take a lot more time with the 500 grit? Too much water and/or soap?

My goal is to create a glasslike mirror gloss, like you see on a high-end car paint job or a guitar.

  • The description almost makes it sound like the orange peel arose from the sanding when of course it should have been there, plainly visible, before you started sanding. So it's there and you need to remove it before you work up the grits, meaning you start with a grit coarse enough to work abrade the finish to the bottom of the pits, then you start the refining and polishing process. In summary, more sanding to begin with (and I'd suggest at a higher grit than 500 which is really quite fine). [contd] – Graphus Aug 2 '17 at 18:16
  • Refining/flattening grits are more in the range of 320-400 and there's no reason you couldn't start at 280 if you were careful and there's enough finish applied that you won't easily wear through. – Graphus Aug 2 '17 at 18:17
  • @Graphus Yes, sorry; the orange peel was there from the start. I just expected the 500 to be more than rough enough to remove it. If I have 5-7 coats of lacquer how long can I expect to be able to sand with a 320 pad before I burn through to the wood? I've been afraid to go more than a few slow passes with 500, but maybe I'm being far too cautious? – Nicholas Aug 2 '17 at 18:47
  • That's a "how long is a piece of string?" question I'm afraid. You sand until the orange peel is gone and that takes as long as it takes. There's no way of saying otherwise without knowing how fast the paper cuts and the freshness of it. But additionally how fast the sanding is being done, how much pressure is being applied and a couple of other variables all factor in. But essentially it boils down to this, you're done when you're done. – Graphus Aug 2 '17 at 21:25
  • 1
    That's what you have to do to check progress, wipe fully clean. You might have better luck (i.e. it'll be faster) if you can squeegie the surface off, if there's a suitable rubber tool on hand, but if it takes wiping thoroughly clean, drying off and assessing then under bright light that's what it takes. Nobody said it was going to be easy! :-) – Graphus Aug 3 '17 at 14:37
2

I'm going to quote the pros - the folks who make HVLP systems to answer this. Answer from http://www.fujispray.com/orange-peel-help/:

The number one issue for orange peel is that the material is too thick.

To remedy this, add more thinner (or appropriate solvent) to the mixture. For fast drying products such as lacquers, you may also want to add a lacquer slowing agent such as Floetrol. This will slow the drying time allowing the material to flow out and level nicely.

With the newer water-based materials orange peel is usually a result of spraying on too thick of a film. Try spraying an extremely THIN FILM, but still WET coat. A wet coat being “no dry spots that you think will flow together” and at the other end “no puddles or runs”.

Remember don’t turn the air down too much. The more air used, the finer the atomisation will be.

This is why we suggest leaving the air control valve fully open when experimenting with a new coating material, otherwise it will cause confusion. If the air control valve is fully open (or perhaps removed for Latex spraying) then orange peel can only be one cause – our number one factor, the material being sprayed is too thick and must be thinned.

| improve this answer | |
  • Thank you. I may be spraying too thick; when angled against the light I see clearly wet areas (I guess 'puddles'), and other drier areas. I'll turn down the spray speed and try to get more even coats. For water based acrylic lacquer, is water the 'appropriate solvent'? – Nicholas Aug 2 '17 at 15:50
  • @Nicholas yes water is the solvent you use but there are other retarders that might be needed as well depending on the product, conditions, etc. – Steven Aug 2 '17 at 16:56
  • Thank you for your suggestion. I tried this with two different spraying sessions using varying amounts of water under the guidance of the manufacturer. It did decrease the orange peel effect a bit, but to get that glass-like finish I needed to step up to much more aggressive paper per Graphus' suggestion. As such, I'm going to mark that as the answer, but I have upvoted yours. – Nicholas Aug 16 '17 at 18:44

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.