Glazes and crackles

      How to use glazes and crackles to produce dramatic effects. November 21, 2000

Q.
What brands of glazes work best over lacquers? Also, if you add a crackle to pigmented conversion varnish will it crackle?

A.
As for glazes, you need to play with what you can buy in your area. All industrial type glazes work very well. Some people want a long open time and some need quick recoat windows for production reasons. One thing to do is use a product that is compatible with your finish system and always test your system on samples first!

As for the crackle, NO. Crackle is a product in itself, and if you need to pigment some you must go easy on the pigments, as it will affect the crackling. There are several ways to do a crackle finish. Tell us what you are doing and maybe we can help you out.

Bob Niemeyer, forum technical advisor



Bob: there are several ways to do a crackle finish with conversion varnish? Could you outline them here on the message board? I think that is what the original questioner was looking for. I know that I am.

I have seen retail kitchen cabinets done with a crackle finish and a conversion varnish system. So I also wonder how they do that.



First off there are several ways to do a crackle. One is using the old Lepaghes Bookbindng glue and then topcoating with a waterborn product to crack. I found this system to take conversion topcoats if fully cured.

Then the old NC system. This is what most people use in production for speed and ease. And there are crackles developed for use with conversion systems. Just ask for them from a company that makes products for OEM's. The problem is that thay make it custom for the customer and for someone to want an extra fiver is hard to do. Plus most people here seem to need only a quart or a gallon at most.

Bob Niemeyer, forum technical advisor



From the original questioner:
What I need is a brown base coat with a tan or biege crackle over it.

Do you have a dist. nearby to use? You need to lay down a gloss basecoat tinted to the color you want, then lay down your tinted crackle. Crackles don't need much tint as the mil thickness is very high, thus you get good hiding quickly. At this point many crackles are glazed or have some other process done also before the seal/topcoat is applied.

Bob Niemeyer, forum technical advisor



Easy crackle recipe:

1) Go to Home Depot and pick up a gallon of Ralph Lauren Crackle Medium (water based).

2) Pick up your latex base color (color seen through cracks) and your latex top color (top coat). Get the flattest sheen available.

3) Prime your project with heavy latex primer, sand and apply the base color.

4) Sand with 220 lightly and spray the crackle medium (thinned out 60% medium to 40% water), allow to dry to a tacky feel. You can leave the medium overnight and it will still crackle the next day.

5) Apply your top color (thin out about 40% with water. The thicker you spray the topcoat the bigger the cracks will become. This takes a little practice. The more water you add to the mix the smaller the cracks will become. If you don't have enough cracks a heat gun will make them bigger.

6) Let the whole thing dry thoroughly (up to a week sometimes), sand lightly with 320 and apply a coat or two of conversion varnish. Yes this works! I have pieces out there for years now.



Conversion varnish can go over latex once fully cured no problem, most of the time. The above system is fine for one or two pieces but for production I think we would be in the poor house real soon.

Bob Niemeyer, forum technical advisor



Bob is 100% right, the process is time consuming. We only do a few pieces a year using this method. The thing that really kills is the amount of time you must wait to apply the clear coat. But for small volume it is easy and materials are flexible, available and cheap.

Bob, what products and methods would be used on a production scale? Do you still have flexibility of color?



From the original questioner:
I have been using lacquer with an additive made by Star to crack it. Just looking for a better way because it keeps on getting more involved.


Here is what I have learned but never have tried: two minutes after shooting the tinted conversion varnish, shoot on your crackle. This is the regular crackle just like you would get from Star.

After drying, sand the sharp edges of the crackle to dull them. Topcoat with your clear conversion varnish.

I was told that the two minutes between conversion varnish application and crackle lacquer is critical. It sounds like you have to be really well-planned so that you can move quickly and still not shoot the crackle too heavy or too light. This is something that is half materials, and the other 90% technique.



All this talk about glazing and crakling as well as the processes are new (and fascinating) to me. Would you care to elaborate when mentioning specific brands? Like what is Star and where do you get it?


Star is Star Finishing Products. They are an RPM company. You can get Star products online from

http://www.woodfinishsupply.com/

They are sold from local disributors, over-the-counter. Call them in Hudson, NC to find out where you can get their products locally.

Star Specialty Finishes
3194 Hickory Blvd.
P.O. Box 669
Hudson NC 28638

(828) 728-8266

As far as books go, no book covers this subject from this perspective of production finishing. There are not enough finishers involved with the use of professional products that will go out and buy any book, and the publishers all know this.



A few thoughts on crackles. Every time I have to do a crackle I am matching a sample from a designer or another manufacturer. Thus I have had to adapt on every job. As for most production plants, they will use a pre-made formula from a coatings manufacturer. They rub grease or wax sticks on the high release areas first. Some use vaseline also. On some old world crackles I like the glue system and then use a waterborne finishing system. On wearing surfaces I will use a crosslinked waterborne and it holds up very well.

One thing to remember: crackle is a decorative finish and if you need conversion varnish on it for durability and wear, maybe crackle is not the right choice. Everything you use to do a crackle is a "weak link" in a finish system, and then we want to "bury it" in conversion varnish. I think sometimes we need to think outside of the conversion varnish world.

Bob Niemeyer, forum technical advisor



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