Fine Crackle Finish

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Products and techniques for achieving a fine China-like crackle. May 19, 2004

Customers requested a fine crackle finish on the doors and drawer fronts of the maple kitchen I am building for them. I tried the commonly available acrylic crackle glaze with a coat of acrylic paint on top (various cuts and thicknesses for both), but the effect is too coarse - looks like barn board.

I am trying to get a very fine crackle effect, like you see in old China - very thin lines. What should I use for this? What kind of top coat will protect it best?

Forum Responses
(Finishing Forum)
From contributor P:
What is your application process? If spraying a conventional crackle lacquer, the size of the cracks is controlled by the amount you apply: less wet film = finer cracks; heavier film build = larger (wider) cracks.

For me, a standard finishing schedule for crackle would be:

1 - Apply NC primer tinted to desired basecoat color or apply clear sealer over desired stain color. If applying pigmented basecoat, apply enough coats (sand between) to give full-filled finish.

2 - Sand to 320 or 400 (the smoother the surface, the easier the crackle lacquer slides to form the cracks.)

3 - Apply crackle lacquer (tinted to desired color if applicable). Practice on sample boards until you get the desired crack size.

4 - If needed, lightly scuff the crackle with a scotch brite pad or super-fine sponge. Be careful here as the crackle is usually very powdery and will sand off in a hurry.

5 - Apply sealer or self-seal topcoat per manufacturer's recommendations. Some suppliers will allow you to put on one coat of acid-cure TC, some will allow precat only, and some will allow NC only... depends on whose crackle you are using. More than one coat of an AC product will usually cause lifting. You could also isolate the crackle by applying a vinyl sealer followed by your desired TC.

Something to remember: getting consistent sized cracks over the entire piece is very difficult because it's hard to keep your film build exactly the same across the whole piece (if it's a large piece.) Practice, practice, practice, samples, samples, samples!

These are general steps based on the crackle systems I have used in the past. Each supplier's system will be different. Be sure to get clear instructions from your supplier. Most of the problems I have seen with crackle systems stem from incompatibility problems between layers in the process.

From the original questioner:
Thanks for the info. Can you recommend a sprayable product? (I am not too familiar with the terms you are using). Also, is it better to 1) spray the crackle medium between two colors, 2) mix the second color into the crackle medium, or 3) spray on a clear coat that will crack, then rub a second color into the cracks?

From contributor J:
I have found by mistake several times that spraying over a stain or glaze before it has thoroughly dried has caused a similar result... By the same token, a water-based finish over a solvent-based stain that is still tacky (just applied) creates a lovely, crackly finish. Have the mistakes I made ever been used to create an antique look without compromising the integrity of the finish?

From contributor W:
Contributor P's description is excellent and no doubt works fine.

Just for a drill, here's a couple of slightly different takes:

When using lacquers, I like Mohawk's or Behlen's crackle lacquer. I mix their lacquer pigments directly into it. I put down a colored lacquer basecoat and let it dry. Then I put down a coat of vinyl sealer, and apply the crackle lacquer while the sealer is still soft. How long the sealer coat dries before I spray the crackle depends on the weather and what kind of effect I am trying to create.

A thin coat of crackle does indeed make a finer crackle than a heavy coat, and you can learn to control it pretty well with practice, but my control, at least, is never absolute. The sealer coat just gives you more options in how the pattern develops. Generally, the softer the sealer, the bigger the plates. I realize this is contrary to your current needs, but it might be of interest later.

Spraying gives you a mudcrack pattern. When I want a more rectangular pattern I use McCloskey's Special Effects crackle glaze, and apply it with a brush over a base coat, then flat latex paint over it. You can get more of a mudcrack pattern by rolling the crackle medium and then the color coat. Different rollers give different patterns.

You can get interesting effects with more than one crackle coat, and McCloskey also makes a crackle glaze specifically to make a fine crackle.

Hope I haven't muddied the waters too much, but there are a lot of ways to make and manipulate crackles.

From Bob Niemeyer, forum technical advisor:
ICA Wood Coatings has a crackle that looks just like aged crazed finish. It's not like normal crackle that pulls; this looks like cracks in glass or the same type of finish cracks if you overbuild NC. They have another one that almost produces the look of faux leather texture.

I would not use any type of crackle on a kitchen that was going to be used like a normal kitchen, as those areas would be the weakest link of the whole system. If it is a designer show kitchen, I might do crackle in selected areas only.

From contributor S:
Experiment with this - the old fashioned and best way around for strength and endurance. Prime the board, sand 320 grit. Sponge on wood glue, wait a minute, sponge on top with latex primer. Size of cracks are determined by amount of glue on bottom and latex primer on top. Also for effect, spray over with an air gun and practice pressure and distance for different effects. When dry, sand lightly #220, prime, lacquer, glaze, clearcoat. Nothing is stronger or better. Also, you can learn a lot of effects and control the crackling by adjusting the glue, primer and air pressure. Once you get good at this procedure, nothing beats it.

From contributor O:
Finishing schedule before and after is up to you, but take a heat gun to drying milk paint and you can get a look just like you would see on the woodwork of a 100 year old house. The degree of crackle can be manipulated by the quantity of paint and heat applied respectively.

From contributor D:
Let me quote a fellow finisher who has done this with great success:

"50/50 mix flattening paste and MEK. Vary the mix and amount applied to control crackle. Basically, flattening paste keeps the MEK from evaporating too fast. Also, I've gotten great results from milk paint and a heat gun. Forcing the milk paint to dry too fast causes it to crackle (real easy to control)."

From contributor M:
I get the most consistent crackle finishes by using the RFU (ready for use) crackle colored and the clear crackle lacquers. I suggest you buy the base colored coatings, the crackle coatings, and the crackle solvent they sell from the same company to get the best results for your crackle finishes.

From contributor S:
RFU finish is easiest to apply, but is the weakest. If you don't feel confident enough, use them.

From contributor M:
Why are they the weakest, when most professional finishers use RFU finishes?

From contributor S:
Considering the application I posted, there is no comparison in looks or techniques available or strength. You control the process and can achieve different effects that can't be obtained with spray applications. This goes a lot deeper on the techniques used with the application process. You can put the wood glue on raw wood also, followed by the latex primer. It dries like a rock. Blow air on it or just it leave by the spray booth for air flow - more air, larger cracks. More paint or glue, also larger cracks. After dried, you can scrub areas down below the paint surface coating with water and a nylon pad for real neat effects! After dry prime and sand, color and different neat glazing effects due to the application where you lay colors in the valleys and the way you blend it out. The decorators love it.

Another strong one, but with uniform crackle, is ICA Effetti Speciali. This is the strongest out there. Try scratching it - it's like concrete and is the most advanced coating on the market for that effect.

From contributor M:
RFU means ready for use. Any coating you buy from any manufacturer is ready for use, be it lacquer, acrylic, poly, varnish, conversion varnish, polyester.

As far as the glue crackles are concerned, they are known to lift more than the commercial RFU coatings, and are more erratic and unpredictable in their crackling.

They sell prepared, ready for use crackle mediums at most paint and arts and crafts shops.
One medium is used for the small crackles, the second is the large crackles. I have used both types, and find they are a better choice for crackling than using the glue method, because they are more predictable in their outcome.

From contributor G:
I have been experimenting with ML Campbell's new crackle finish. It does work and the size of the crackle can be controlled.

From the original questioner:
Wow! You guys sure gave me lots to experiment with. Special thanks to those of you who emphasized the practice, practice, practice approach. Once I accepted the need for some non-productive time, "Crackle School" started paying off.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor K:
To do the old china cracked finish, use gloss tung oil over lacquer sealer. Spray on some good old fashioned spar varnish, and heat it with your heat gun. It will craze like granny's dishes, but not crack open. After drying, use shellac to topcoat it, followed by one coat of nitro. This is not something that will last a lifetime, but none of them will; this really looks like what you want - the way we used to do it 40 years ago.