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Forum topic by otis501 posted 12-24-2014 09:41 PM 1186 views 0 times favorited 12 replies Add to Favorites Watch
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otis501

28 posts in 2110 days


12-24-2014 09:41 PM

Trouble with lacquer!!!!! I have tried brushable and spray lacquer and always get bubbles and it turns white. I sand with wet 400 paper and spray again but get the same effect. I get this problem with all kinds of wood, sanded to 220 and stained and some sealed with spray shellac. WTF..

Otis


12 replies so far

View JAAune's profile

JAAune

1640 posts in 1779 days


#1 posted 12-24-2014 10:02 PM

Orange peel and/or blushing. It could result from too heavy a coat, insufficient atomization or adverse environmental conditions (temperature and humidity).

A process of elimination will help. For that, you’ll need to make up a bunch of cheap sample boards to experiment with.

-- See my work at http://remmertstudios.com and http://altaredesign.com

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Ripthorn

1406 posts in 2447 days


#2 posted 12-24-2014 10:09 PM

Turning white is blushing. It happens when moisture is trapped under the lacquer and isn’t escaping. The two main causes of blushing are relative humidity that is too high (50-60% is the limit for safe spraying, though you can be successful with it higher if you are careful and know what you’re doing) or getting moisture in your compressed air for spraying. If the latter, drain your tank and use a moisture filter. If the former, you can mix your lacquer with some thinner or retarder. The retarder keeps the lacquer wet longer, giving the water underneath enough time to escape while the extra thinner makes the lacquer coating thinner so that there is less for the moisture to get through. There are also dedicated blush erasers, but they are usually just a mix of thinner and retarder.

A lot of times, just give it overnight to gas off and the blush will go away (but do it in a warm place). If it is too cold, it makes it a lot harder. I spray quite a bit of lacquer building guitars and this is a common problem, but luckily it has a couple of easy solutions.

-- Brian T. - Exact science is not an exact science

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HerbC

1592 posts in 2321 days


#3 posted 12-24-2014 11:07 PM

I’ve used Behlen Blush Eraser and it worked well.

-- Herb, Florida - Here's why I close most messages with "Be Careful!" http://lumberjocks.com/HerbC/blog/17090

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Sawdust4Blood

392 posts in 2483 days


#4 posted 12-25-2014 12:15 AM

I agree with all the above comments about moisture/humidity and blushing.

I’m also wondering how thick you are spraying at one time. In my experience, bubbling occurs when the surface lacquer dries a skin while wet lacquer beneath is still trying to out-gas. I’ve seen that occur from drying in direct sunlight or spraying too thick a coat at one time. I like to build a lacquer finish spraying multiple light coats.

-- Greg, Severn MD

View OSU55's profile

OSU55

1056 posts in 1451 days


#5 posted 12-25-2014 12:21 AM

Most likely spraying too thick of a coat. You dont say what you are spraying with. Poor atomization from cheap guns can cause you to shoot thick coats to get it to level

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,

2387 posts in 3009 days


#6 posted 12-25-2014 01:07 AM

We spray lacquers several times a week. The bubble or orange peel is more an affect of inadequate pressure setting. A cheap gun should not be an issue, we use the 40.00 gun from woodcraft with excellent results. The key to proper atomization will be proper air pressure. Practice makes perfect in this regard. The turbine systems are good for atomization of lacquers as it takes some of the guess work away from someone who is just starting out.

As for blushing, yes it has to do with water trapped inside the finish. This is controlled by spraying during optimal weather conditions, such as at high noon with warm temps. Again this is best learned with practice. No product d3signed to remove blushing is required, that seems like a ploy from a company to dig into our wallets. Lacquers are easy to use and can be self forgiving by spraying one more coat at a later time when weather is optimal for spraying. All subsequent coats sprayed will re activate previous coats allowing coats to burn into each other and also allowing for easier repairs.

blushing can also be controlled by the use of retarders in your lacquers.

As for spraying to thick, I would disagree. We spray all of our coats at 3cm each with great success. My suggestion would to strive for 3 cm material laid per coat. The thickness of coating would need to be thinner, like 1.5 cm, when spraying vertical applications. Most all spraying should be done horizontally whenever possible.

-- .

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Sawdust4Blood

392 posts in 2483 days


#7 posted 12-25-2014 02:14 AM


As for spraying to thick, I would disagree. We spray all of our coats at 3cm each with great success. My suggestion would to strive for 3 cm material laid per coat. The thickness of coating would need to be thinner, like 1.5 cm, when spraying vertical applications. Most all spraying should be done horizontally whenever possible.

- Jerry

3 cm is over an inch thick. Did you mean 3 mm?

-- Greg, Severn MD

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otis501

28 posts in 2110 days


#8 posted 12-25-2014 05:14 PM

thank all

Otis

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,

2387 posts in 3009 days


#9 posted 12-25-2014 06:09 PM

Yeah, I get the metric system confused sometimes. After a quick search, i discovered the proper term is “mil”. So we lay around 3 mils per coat, or that is what we aim for. A mil is .001”. There are small measuring devices available at the paint stores that can be used for measuring how thick your application is on the project.

Thanks for the correction, it saves me from my own ignorance.

-- .

View Tennessee's profile

Tennessee

2410 posts in 1976 days


#10 posted 12-25-2014 10:10 PM

Spray lacquer is one of my go to finishes for small items that will not see a lot of use, such as hat racks and business card holders. I use mainly Deft and Valspar spray, unless the project is big, then I use Minwax fast drying lacquer with a spray gun.
I sometimes see blush, the white opaque color in the lacquer after I spray, especially after a humid day.
It always goes away, if I simply let it dry enough. The water gasses out through the lacquer, and all is well.
If you are having real problems, then I suggest if the project is small enough, take it into your house and put it somewhere where it will see the temps and humidity of your house overnight but be safe from your family and pets. It should clear up within 12 hours. To date, after about five years of this with my galleries, (not very often but enough where I live), I have yet to have this method fail.

-- Paul, Tennessee, http://www.tsunamiguitars.com

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,

2387 posts in 3009 days


#11 posted 12-25-2014 10:39 PM

In using lacquers, I would also strongly recommend seeking a good pre cat lacquer as your go to material. You will never regret using a higher quality pre cat. That small simple lesson took me far too long to learn and you can avoid some pain from just going with pre cat sooner than later. We use a product from ML Campbell. We dont thin the product and our top coat is self sealing so no other sanding sealer is required.

-- .

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OSU55

1056 posts in 1451 days


#12 posted 12-26-2014 03:40 AM

Cheap guns need a lot of air to atomize, creating excessive overspray and of course consuming more air possibly requiring a larger compressor. A 3 mil wet thickness is a moderate wet coat and would not cause blushing under reasonable environmental conditions.

Since you have the issue with brushing and spraying, it’s very likely cold and/or damp environmental conditions or surface contamination. What is the temp and humidity when finishing? What is your surface prep process?

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