Seeking the perfect cure (... if there is such a thing)
The perfect cure is as mysterious to define as it is to create. A few experts take a stab at it
by David WIlliams
Seeking the “perfect cure”
By David Williams
The 19th-century poet Robert Browning once said that “a man’s reach should exceed his grasp—or what’s a heaven for?”
What does that have to do with curing tobacco? Maybe not much, but it was on our minds as we asked growers, academics and retailers alike:
“Is there a perfect cure?”
We knew the answer was somewhat academic in nature. In all likelihood, there is no such thing as a perfect cure—one idyllic, unchanging formula that guaranteed perfect tobacco. But just as Frost hinted with his statement, we also surmised that if a grower goes over both the small things and big things as he seeks to get a perfect cure, he might be able to find a few things he can make better, and in so doing get a better crop—perhaps not perfect, but surely better.
Bob Pearce, tobacco specialist at the University of Kentucky, put it in better terms.
“In my opinion, it would be impossible to define a perfect cure,” he said. “Much like the saying that ‘beauty is in the eye of the beholder,’ the definition of a perfect cure depends on who is evaluating the product.”
Perfect in what way?
One of the first things discovered in discussing a perfect cure was that the phrase “perfect” has a lot of other meanings.
To Paul Sumner, tobacco specialist for the University of Georgia, a perfect cure begins with perfect materials.
“The first thing you have got to have is good-quality, ripe tobacco to go in the barn for good tobacco to come out,” he said. “You can hardly mess up a barn of tobacco if it is ripe tobacco that goes in—that has not been stressed, that is not over-watered or whatever. Once you get it in, and it has got to be ripe. If it is over-ripe, you have got to watch how you color it, and how you go up on the heat so you don’t turn it brown. If he puts in immature tobacco, it will have a green cast to it when it comes out.”
For others, a perfect cure had to do with a cure that was controlled perfectly in terms of expenses. Burley growers, for example, would be more interested in the cost efficiency and labor savings of tensile-wire outdoor structures versus building a traditional barn, while flue-cured growers would consider the cost and efficiency of gas-fired barns or oil-fired barns. Others would consider how practically the curing environment is controlled, whether by careful human monitoring or by modern automated control systems.
Talk it out
Talking with the buyer—and not just at contract-signing time—is vital for a cure, and a crop, to be perfect to the purchaser.
“You have to have good communication somewhere along the line,” said Pearce. “Certainly, in-season communication will allow adjustments to be made as it goes along, But oftentimes, we see more communication toward the end of the season, when the grower brings his tobacco into the buyer and the buyer either says, “Yes, I like this,” or “No, I don’t like this style.” I feel like the buyers of tobacco know what they want when they see it, in terms of the quality aspects that are there. But sometimes they are in a position of giving a grower advice on how to achieve that, and they may be basing that advice on limited observations or anecdotal evidence. If we have constant communication and know what the buyers want, then we can work together to advise the grower on how to produce a particular style of tobacco.”
Sumner saw the perfect cure from a similar perspective.
“I don’t know if there is such a thing or not, because that all depends on what they are buying,” he said. “I have seen beautiful tobacco come out of the barn, and that was not what they wanted to buy, so that was not the perfect cure.
“You very much need to know what they are looking for,” Sumner said. “If they want a lemon-yellow-colored leaf this year, you need to find that out. If they want an orange leaf, you obviously change your fertilizer requirements and you run the temperature up a little bit, and you can get a little caramelizing at the end of the cure, and it will turn it orange.”
The perfect burley cure
Pearce provided an interesting take on the perfect cure—sometimes, the winning move is no move at all.
“In Kentucky, we can get acceptable curing of burley tobacco in about 6 out of 10 years with little or no management of curing—open the doors and ventilators when the tobacco is hung and close them 6 to 8 weeks later,” he said. “In the other years it may take opening (night) and closing (day) of the ventilators on a daily basis to get a good cure.”
This rationale is providing the impetus for growers to use outdoor curing structures—wooden frames strung with high-tensile wire that can stay outdoors and be wrapped in plastic as the crop cures. Outdoors, the crop continually goes through a daily cycle of high and low humidity.
“For a limited management cure, where the grower is not going to put a lot of additional effort into the curing … put the tobacco on there,” Pearce said. “From that point nature does a pretty reasonable job in most cases. In an outdoor structure you typically have a single layer no more than two rows wide that [is] exposed on a daily basis to the atmospheric conditions, so [it] would go through drying cycles during the daytime in the relatively low humidity, and at night (in high humidity) the crop would come into order. This daily cycle seems to produce a pretty good cure in most seasons.”
In a barn, the key is getting air moving through the leaf. With more limited air movement, a grower has to get more involved.
“We have kind of fallen into a habit of putting the tobacco in, opening everything up, leaving it open for the first two to three weeks, and in many cases we just leave it open and let it cure throughout the process,” said Pearce. “Under conditions of low humidity and high temperatures, when the tobacco is drying very fast, if we want to get the best cure we have to close down during the day to try and retain some of that natural moisture that is in the crop, and open that up in the nighttime and the evenings to let the higher relatively humid air come in, and close it again the next morning to trap that humidity.”
Trade-offs are inevitable if a grower is considering whether to build more barns or switch to the less costly outdoor structures.
“(With outdoor structures) you do lose a little bit of curing control, and you are taking a certain element of risk there,” advises Pearce. “A barn is a pretty sturdy structure, not that we couldn’t have a strong enough storm to blow it down. But with outside structures, particularly late in the curing season, when we start to get more fronts moving through and with potentially high winds, this creates a risky situation when the crop is exposed in an outside curing structure.”
Pearce’s advise to growers using both barns and outdoor structures is to go outdoors first.
“Curing structures get the first tobacco that they harvest, and have it be the first they take out, before it gets to that period where we have more storms and fronts that could damage the crop.” he said. “There is that trade-off from the risk standpoint. There is the lower cost from construction, and lower labor costs for the outside curing structures.”
The spacing of the sticks, so important in the burley cure, is based mostly on air movement through the leaf.
“The less natural air movement that you are going to have, you would need to have the spacing wider to allow for that limited air movement to get through the crop,” said Pearce. “A lot of the stick spacing will depend on the design of the curing structure as well. If we are going on the outside curing structures, generally with burley we can put the spacing a little bit closer than we can, say, in a barn where there is a little less air movement. In a tight barn, or one of these barns with sheds on both sides, or in situations like that where your air movement is limited, you would have to space it out more so than in a more open barn or situation.”
Pearce said he believes that growers—especially some of the larger growers—have fallen into a hands-off approach to curing.
“Large growers may have so many barns they might not have time to get around to all of them opening and closing the doors, and doing all of the little things necessary for the perfect cure, so the tendency is to open them up and let them go,” he said. “Some barns have been intentionally built with gaps in the siding of the barn, for air movement in curing. Those are almost impossible to manage for curing during a dry curing season—you are going to get what you get from those types. So there is really no magic formula for the perfect cure; maybe we just need to get our minds around the fact that curing burley tobacco is a process.
“It is not just drying tobacco—it’s a process, and it takes time,” he said. “You can’t rush a good burley cure.”
The perfect flue-cured cure
A prefect flue-cured cure has a lot to do with not messing anything up, according to BulkTobac’s Frank Horne Jr.
“The perfect cure is not to ruin the tobacco, honestly,” Horne said. “The one thing you can never do when you cure tobacco is make any better tobacco than the grower puts in the barn to begin with. He grows the tobacco. When it comes out of the field, all you can do in curing it is hurt it—you can’t improve it. It’s like baking a cake—if you have the right ingredients, the cake tastes good after it is baked. And you have to bake the cake.”
The basic goal of flue-curing is to yellow the leaf, which is actually a chemical change in the leaf through heat exposure that converts the starches in the leaf to sugars, then to dry out the leaf.
“Use a wet-bulb thermometer and follow the curing guide we offer, as well as North Carolina, or South Carolina or Virginia, and go with it, it will work,” said Sumner.
The art of curing comes in the timing of the yellowing and the heat and humidity control in the yellowing and drying process.
“When you start to increase the temperature to wilt the barn down, you want to make sure that the whole barn is wilted down completely before you leave that 130-degree or 135-degree mark dry-bulb and go on up on the temperature to dry the leaf on out and start killing the stem,” said Sumner. “Once you have passed that point in the game, there is nothing you can do to it to salvage it.”
Sumner said that growers that have gone to leaf-loading systems are enjoying a curing benefit in that they can get a uniform weight and density to their boxes.
Loading the boxes into the barn, Sumner noted that the spacing between the last box in the barn and the door needs to be as minimal as possible, and many growers block the air space created between the box and the door to ensure the air goes through the boxes, and not around them.
“That way you can get uniform coloring, uniform wilting in the barn and uniform drying,” he said. “You won’t have any boxes at the end of a cure that have swelled stems in them because they didn’t dry properly.”
Barn maintenance is critical between cures, including monitoring the sock on the wet-bulb sensor to prevent bad readings. The sock will gum up from tars drawn out from curing. Sumner also said the barns should be cleared of loose leaves at this time.
Automated curing systems
Horne offered another vision of the perfect cure.
“If a perfect cure is curing for the lowest cost you can … that may be the better definition of a perfect cure versus what you are going to have on the leaf,” he said.
Growers, always careful to grow in the most cost-effective manner possible, can relate to Horne’s version. A cure performed with as little fuel costs and labor costs as possible would have to be considered as near perfection.
Many new automated systems are changing the way leaf is cured—not so much the process as the labor-intensive techniques. Some systems have even eliminated the need for a wet-bulb thermometer.
Horne said that BulkTobac developed the first automated curing system back in 1977. He said automated systems provide “a combination of adjusting the amount of air that goes into the curing chamber to the least amount necessary to dry the leaf.”
Horne explained further. “It’s as simple as this—if you put too much air, it is just like heating your house with the windows open,” he said. “You can still heat the house, if you have a big-enough furnace, and you are going to be warm in your house, but your gas company is going to love you.”
Horne said the best thing a grower can do to improve his curing costs is to check the efficiency of his operation – starting with a smoke bomb.
“The very first thing we always say is take a smoke bomb and put it in the barn, see where the leaks are and fix them,” he said. “That is the number-one thing, and the cheapest thing—just closing the leaks. You can have a year-old barn or a 30-year-old barn, and they can still change by expansion and contraction and start leaking more this year than they did last year.”
Horne said that not only the process of curing but also the expansion and contraction due to exposure to sunlight and regular atmospheric heating and cooling will create surprising leaks. Horne sells pressurized systems, and under those conditions heated air can literally blow out of a barn leak like a tire that has been punctured.
“The farmer’s great line is normally, ‘Well, it cured fine last year. I don’t know why it changed.’ Well, what has changed is that they are probably leaking some air … smoke bombs are relatively cheap, and you put them in a bucket and you turn your furnace fan on and you see where the leaks are.”
Growers can realize long-term savings on fuel for heat exchangers—and prolong the life of the exchanger—by letting them run longer cycles.
“People tell me the problem with heat exchangers is the constant heating and cooling,” Horne said. It is like bending a coat hanger back and forth repeatedly—eventually you will crack it. So the best thing for the heat exchanger is to run it as long as possible on the cures—you get more efficiency because you brought it up to temperature, and it will extend the life of the heat exchanger.
Horne said atmospheric burners that operate on high-pressure gas can run longer simply by turning down the BTUs with the hand valve.
Another good piece of advice for gas-fired burner users is to check for leaks in the gas supply line from the tank to the burner with a soap suds and water solution. Oil-fired burners need regular maintenance to burn efficiently.
“Periodic adjustments of the air plates on other burners will help as well, using a CO-CO2 analyzer that measures the losses in the stack and helps you assure the air and fuel mix is optimum—like taking your car in for a tune-up,” said Horne.
Tommy Dew of EvenCure Systems believes in the advantages of modern technology, such has what his company offers to growers. EvenCure has a full line of automated systems, from barns to heat exchangers to motors and humidity controls.
“Some of the things I have seen in the past 8 to 10 years of traveling to farms reminds me of what my grandfather used to say: ‘Son, if you don't change with the times, then Father Time will leave you behind,’” said Dew. “The time for change is happening at a very fast pace today, with the world economy and the growers’ landscape much more diverse and changing faster than ever before.”
Things changed in the last 25 years on the farm because of a need for greater efficiency. That need is still there, and Dew said the automated systems he offers are a continuation of that need for still greater efficiency.
An example is EvenCure’s new humidity controls, which replace the wet-bulb thermometer.
“I believe that the wet bulb, discovered in 1750, has exceeded its potential for usefulness or life expectancy, even though it still has some usefulness and has been a good tool for the past 258 years,” said Dew. “Our new humidity controls—the only one on the market—are on their way to becoming a great tool for the growers of today and beyond.”
But accepting new technology is something that growers do slowly—even generationally. Mack Grady of Cureco Inc. spoke of an example of how the automated systems he sells are gaining acceptance one barn at a time.
“I sold a system to the son of a grower that did not want it,” he said. “We put it on a barn. And his daddy said, ‘Well, you cure in that one.’ He did cure in it, and his daddy noticed that when he was out at night checking on the barn, his son was not. And the cure came out the same, or better. He told his son, ‘You’d better get some more of them.’”
So is there a prefect cure? Yes … and no. There is not one process that guarantees a perfect result, mostly because there are too many variables and too many processes.
But perhaps the talent and artisan craftsmanship of growers who know curing—and how to adjust with the times—makes it unnecessary to have a perfect cure, anyway.
Perhaps Salvador Dali, the artist, said it best. “Have no fear of perfection—you’ll never reach it.”