Tag Archives: pre-treat
Pre-treatment is quite possible one of the most critical components to the high-quality DTG equation; too little pretreat chemical and your print results will surely suffer, whereas too much pretreat chemical can easily compromise your wash results. In addition to finding the right volume of pretreat for the specific garment you are printing, you must also take steps to minimize fibrillation and reduce “pre-treatment marks” on the garments (you can read more on pre-treatment marks by clicking here).
There are many different ways to apply pre-treatment to blank garments, but the most common methods include the use of a Wagner HPLV (“High Pressure Low Volume”) spray gun or some sort of automatic pre-treatment machine (such as the ViperONE Automatic PT Machine). Some DTG machines, such as the Kornit brand of printers, actually apply the pre-treatment while the shirt is loaded on the machine; there are basically two schools of thought on whether or not this makes sense, with one side advocating for the ease-of-use and reduction in the overall number of steps required to print, and the other side claiming that the inclusion of the pretreat step on the machine actually reduces overall efficiency (since it can’t start printing until the pretreat step is done, causing downtime at the printer) and presents the possibility of a “single point of failure” (if the pre-treatment nozzle becomes compromised or starts acting up, your entire print operation is offline). Personally, I prefer to do the pretreat step off the printer, for a number of reasons:
- If a Wagner HPLV spray gun starts giving us trouble, we can easily replace it at any time; we even keep extras around at all times, reducing the possibility that we will be stuck without the ability to pretreat shirts.
- By pre-treating the garments off the machine, there is no downtime at the printer itself. We simply load up shirts that are ready to be printed, and the printer continues to spit out completed product without delay.
- When pretreat is applied on the machine itself, there is no opportunity to heat press the garment to flatten out the fibers and evaporate the excess PT fluid – this reduces the overall clarity in the print, and can leave room for fibers to stick up after the pretreat is applied.
Having said that, here is the basic method we use at Fusion Logistics Group to pretreat our garments (using a standard Wagner HPLV sprayer). In the following example we were pre-treating a standard black t-shirt for a left chest DTG print:
- HEAT PRESS THE GARMENT: Before pre-treating any garments, it is a good idea to heat press them to flatten out any loose fibers that might ruin your awesome DTG print. We set our heat press to 340 degrees Fahrenheit and pre-press each garment for approximately 10-15 seconds (using MEDIUM pressure); you don’t need to press for too long because the garment will be under the heat press another 2-3 times by the end of the production process. Depending on the type of garment you are printing on, you may or may not have to perform this particular step – if you stick to higher quality ring spun cotton (the tighter the knit count, the smoother the print surface) you should see much less fibrillation than you might find with a standard cotton garment. Additionally, garments that have received an Enzyme wash during manufacturing seem to show far less fibrillation, primarily due to the fact that the Enzyme wash “burns” off most of the rogue fibers before the garment ever leaves the manufacturing facility – ask your garment providers which styles have been treated with an Enzyme wash, and see if that helps your overall printing quality! Also, notice we are using a Stahl’s Hotronix draw press at the moment – we do not currently recommend this particular press due to its lack of an auto-release feature; when things get hectic in the shop, the last thing you want to be doing is chasing down the beeping heat presses – an auto-release press would allow you to leverage your time more effectively, without the fear of accidentally over-curing or forgetting the garment completely. Auto release clam-shell presses are priced very competitively compared to standard clam-shell or draw presses.
- SPRAY THE GARMENT WITH PRETREAT FLUID: After the garment has been pressed, we drape it over a simple shirt board that we made from inexpensive laminate particle wood from the Home Depot. Before you begin pre-treating for the day, it is recommended that you take a few moments to dial in your spray gun – you want an even, gentle spray that doesn’t sputter or spit any wild drops of pretreat fluid all over the place. The Dupont pretreat fluid is a sticky, corrosive chemical that can easily gum up the spray gun if left unattended for lengthy periods of time (even a few hours could cause a deterioration in spray quality) - to combat this, we typically pour the contents of the spray gun back into the main pretreatment container about every 4 hours; we rinse the gun with warm water, shake the main pretreatment container then reload the gun. Some might say that is overkill, but our results have been far more consistent than they have ever been since we implemented this process…. Once we begin spraying the garments, we usually spray “left to right” then “right to left” on the next step down, releasing the trigger on the gun at the far right and far left of each spray; we repeat this until we have gently covered the entire print area with spray, as evenly as possible. If you hold the trigger and simply move the gun back and forth, you will end up with much heavier deposits at the outside edges of the spray area – look for a YouTube video of a professional painting a car with an HPLV sprayer and you can use that as a model for how it should be done. Once the first coat is done we immediately make another pass (moving left to right and back again, while working our way from top to bottom) – two lighter coats provides more even coverage and allows you to use your judgement on a “garment by garment” basis regarding when enough is enough (fleece often requires a heavier deposit, whereas thinner ‘fashion’ style garments will often require a far lighter pre-treatment deposit).
- BRUSH THE GARMENT TO REDUCE FIBRILLATION AND CREATE EVEN COVERAGE: Before heat pressing the garment again, it is important to spread out the pretreat fluid and ensure that the cotton fibers are pressed down into the garment; with all the moving around within the shop, it is easy for those fibers to work their way up (creating a less-than-ideal printing surface). Some people prefer to use various types of foam rollers for this particular step, but we find that the foam rollers do more to hurt the process than to help it – while it may help spread the pretreat fluid evenly, the porous foam tends to lift the fibers more than pushing them down. We use premium Wooster paint brushes for this step, and our experience shows us that the difference between the two is visually noticeable. Using long, even strokes, draw the brush downward across the garment in strips until the entire print area has been covered (it doesn’t hurt to go over the entire area twice, for that matter).
- COVER GARMENT WITH QUILON PAPER AND HEAT PRESS: As is typical with most pretreat fluids, you must heat press the garment after applying the chemical to ensure it is dry and flat when you load it onto the DTG printer (there is at least one exception to this rule, which is the Kornit brand which applies the pre-treatment on the machine itself then prints ink directly onto the wet pretreat). For this process, we cover the entire pre-treated area with a special Quilon paper, then heat press for 20-30 seconds @ 340 degrees Fahrenheit (using HEAVY pressure) – ideally, the pre-treated area will be almost invisible when you are done with this step (if everything was done properly and you haven’t applied too much pretreat to the garment). The time and temperature required for this step is going to vary based on a number of technological and environmental variables (the type and quality of heat press used, as well as your elevation, relative humidity, temperature, etc) – make sure you press the garment long enough to fully cure the pretreat, while avoiding the risk of over-curing it and potentially burning out the active bonding agent that holds the white ink in place; your exact time and temp may vary, slightly! We have found that the heavier pressure during this step, combined with the brushing from the previous step, seems to do a great job of creating a smooth, ideal printing surface; fibrillation is minimized and we get very little “pitting” in the image. We did an installation for a customer a few months ago who had a pneumatic heat press system, which looked to me to be the best thing I have seen for this step of the process; when the time is right, we will definitely upgrade to a pneumatic heat press system (with a shuttle to improve productivity) that will provide consistent and repeatable results during this critical step.
- REMOVE THE QUILON PAPER FROM TOP TO BOTTOM: Once you have heat pressed the garment and cured the pretreat fluid, you should carefully remove the Quilon paper by pulling from the top to the bottom; this helps ensure that you are not pulling fibers back up from the surface of the garment, which is easily possible when lifting from the bottom. Start at the top and gently pull the paper down in a smooth, even manner; if there is any resistance when taking the Quilon paper off of the garment, it sometimes helps to press the garment without any paper for an additional 10 seconds – this will ensure that the PT is dry, and will push down any fibers that might have been pulled up when you removed the Quilon paper. This step is not always necessary.
- VOILA! YOUR GARMENT IS NOW READY TO PRINT! Once you have pressed the pretreat fluid, your garment is ready for printing and can be loaded immediately onto the platen for DTG printing. You can load the garment straight from the heat press to the DTG printer, or you can stack the pre-treated garments for later printing. Many people ask how long they can let their garments sit after they’ve been pre-treated; while we have seen some garments boxed for 2-3 months prior to actually printing (with no negative effect on print quality), it is important to ensure that they will not be shuffled around an excessive amount of times, due to the fact that you don’t want to raise the fibers on the print surface or cause any undue static electricity on the fabric, as both these things can easily reduce the overall print quality.
SOME IMPORANT THINGS TO CONSIDER: Below are some critical tips and tricks that we have discovered or learned over the last several years; we are constantly learning new tricks, so of course we will keep you posted if we find new information that will help the general public.
- Although adding an excessive amount of pretreat fluid to a garment can certainly result in a vibrant, amazing print from your DTG printer, we caution you not to overdo it! Too much pre-treatment actually creates more of a barrier than a bonding surface, and while the print will look great right off the press it will almost certainly flake and peel off in the first wash (you’ll know it when you see it – the ink will literally peel off in large, connected areas; it’s like peeling the shell from a hard boiled egg). If a garment is pre-treated well but then not cured properly, the image would experience noticeable fading after the first wash, and there would most likely be areas where slight flaking is evident; however, in the case of too much pretreat there will be little time for fading to occur, as much of the image will be destroyed right away in the first wash.
- If you add too little pretreat fluid, the print will look faded and splotchy, regardless of how well your DTG printer is operating. Even the best white ink printed at the best possible settings will look like garbage if your pre-treatment layer is not done properly! Practice this step until you have become an expert, and your time will be well spent.
- Crank the pressure up as much as possible when actually curing the pretreat fluid on the garment – you can reduce the pressure significantly for the actual curing of the printed image (not shown in this brief tutorial), or use a separate heat press altogether. A pneumatic heat press will provide more consistent, even pressure, without the need to work extra hard opening and closing a high-pressure heat press.
- When manually pre-treating a garment, take care not to spray too much on the seams or sleeve-lines – since these areas are raised slightly more than the body of the garment, they will receive slightly greater pressure under the heat press, which could ultimately cause light white pretreat marks to appear on these areas (sometimes they will show up as light white marks on the garment, while other times they will manifest as a mildly reflective sheen that looks different than the rest of the garment). Of course this effect will be less noticeable after the first wash cycle, but the best way to control this is to avoid spraying the sleeves / seams as much as possible.
When using DTG printing as a decoration method, there are many additional steps that are not necessarily required for traditional decoration methods (such as screen printing). For example, many people are not aware that we must spray a liquid “pretreatment” chemical on all dark garments before they can be printed using the DTG process; this additional step is required to ensure that the white ink that is printed onto the garment does not “soak in”, literally disappearing before your very eyes.
In addition to the requirement that we must currently pretreat all dark garments, we are often asked to pretreat light garments as well (the improved color vibrancy and washability on light garments is worth the extra cost) – once again, the pretreatment liquid acts as a “barrier” to prevent the CMYK inks from soaking into the garment. Without this pretreatment on light garments, the print would appear slightly more faded, although still acceptable (whereas dark garments literally cannot be printed without the pretreatment step).
During the curing process, the pretreatment can discolor slightly, and can sometimes leave a slightly off-white residue that may be interpreted as a stain of some sort. This is entirely normal and should disappear with the first wash of the garment. If you want to test it out, try wetting a clean cloth and gently wiping around the edges; you should notice that the effect is minimized, which should offer some reassurance that the first wash will indeed take care of the phenomenon. When pretreatment is applied to certain light garments, the curing process will sometimes cause a light “yellowish” box to appear around the design – again, this is most often caused by normal discoloration of the pretreatment fluid on the garment, which should come off in the first wash. The pretreatment residue is completely harmless (just don’t try to eat your shirt and you should be fine) and is used by any person who is using a DTG printing system; unfortunately it is simply a fact of the industry at this point.
Aside from the possible discoloration of the pretreatment fluid itself, you may also notice a “box” around the printed design – this box is can sometimes be caused by the pressure from the heat press (used for curing the inks) forcing the fibers down into the garment. Since we are applying high heat and heavy pressure for an extended period of time, this box will sometimes be noticeable until the garment goes through the first wash cycle. Additionally, thicker items such as fleece, and items that contain polyester will usually have a harder time masking the difference between the area that has been heat pressed and the area that has not; once again, the first wash should take it back to normal.
Some garments will show an enhanced version of this effect, while other garments will show no signs of the pretreatment area at all – at our sister company (www.fusionlogisticsgroup.com) we try to encourage all of our clients to select garments based on the following criteria:
- How well they print
- How well they wash after curing
- How well they accept the pretreatment fluid
DTG Print Solutions is pleased to have been given the opportunity to become an early BETA tester for the ViperONE automatic pretreatment machine, which is being delivered to the market by i-Group Technologies, LLC (the same team that brought out the original Viper automatic pretreatment machine). For many years, our sister company Fusion Logistics Group has gotten by with the traditional Wagner HPLV sprayer for manual pre-treatment application – the results were not always perfect, but the process has become far more forgiving and manageable in recent years. Printing thousands upon thousands of shirts has made our staff incredibly knowledgeable regarding the manual application of pre-treatment, and we have come to accept this as a normal part of the DTG printing process. Although we have indeed tested other automatic pre-preatment machines in the past (including one which sat dormant in our shop for over a year before we got rid of it), none have ever delivered upon our expectations of reliability, consistency and quality. That all may have changed, however, with the introduction of the new ViperONE pre-treatment unit.
Our staff was eagerly anticipating the arrival of the new ViperONE pre-treatment machine, long before it actually arrived – since we got our hands on a very early concept model, we had to be patient while the necessary adjustments were made by the manufacturers; we were kept informed during the entire process, and when our delivery date came it was like an early Christmas. At some point in the mid-afternoon, I received a call from my production manager to inform me that the pre-treatment machine had arrived – he asked me what I thought we should do with it, and my response was “Well if you feel so inclined, feel free to set it up and take a look at it – otherwise I will be in the shop in a few hours”… Imagine my surprise when the response from the other end of the phone was “Phew, thank goodness – I already unpacked it 20 minutes ago and have been pre-treating shirts with it!”
This anecdote speaks to the ease at which my staff was able to unload the unit (which, by the way, is incredibly compact), set it up and begin implementing it into our production process; although they were in the early evaluation stages, they had no trouble getting it ready to go with almost no direct guidance or instruction. Ease of use is an incredibly crucial factor these days, especially if you plan to utilize paid employees to do your bidding while you’re in Vegas blowing all your earnings on Blackjack…
As mentioned, the unit is physically compact and occupies a much smaller space than the original Viper pre-treatment machine. This makes it easy to integrate into a small production area, where space is a valuable commodity. Our initial feeling was that there could have been a little more money put into some of the construction materials used to build the unit – in particular, we felt the slide rails were not as sturdy as we were used to seeing on other equipment. We discussed our feedback with the manufacturer, but the feeling seems to be that any improvements in this area would add quite a bit to the manufacturing costs – since we do not build or source the parts, we will have to take their word on that!
The machine utilizes a drawer-style design which involves the main body of the unit (where the actual drawer is), an upper spray mechanism and an assortment of tanks / bottles to dispense and recollect the pre-treatment spray; the machine also requires a small air compressor unit to operate (not included), which is a departure from the original Viper design (which utilized electronically controlled spray nozzles, rather than pressure nozzles). To be completely honest, we were unsure how well the single-nozzle design would work out, considering we have never seen a single-nozzle unit that performed to our specifications – now that we have had some time to fully evaluate the system, we are pleased with the consistent and smooth results we have been able to achieve thus far. Although we notice that the outside edges seem to vary from the center of the spray area, slightly, our experience has shown that this subtle discrepancy has almost no effect on the quality of the prints we are getting on our Neoflex printers. The improved quality and repeat-ability we are able to achieve now in our pre-treatment department has surpassed even our most optimistic expectations, and our printing business has been positively impacted by this change – any slight difference in spray volume seems unnoticeable in the printed image, as the improved quality we are now getting far outweighs any concerns we may have had.
EASE OF USE
Our employees had little difficulty setting up the machine and pre-treating the first couple of shirts – in addition, Brian Walker was kind enough to provide some thorough documentation, including a user guide that helped indicate how much fluid should be applied to get the best results. When dialing in the machine, there is a knob which you turn either direction to increase or decrease the amount of air flow, thereby affecting the volume of pre-treatment that is ultimately applied; we found that it can be a little tricky to determine the “zero point” for the dial, due to the fact there is no hard-stop when turning the dial counterclockwise. A trick we were shown is to rotate the dial until we felt resistance, at which point it was at the “zero point” – from there, each full rotation would increase the spray volume incrementally. This process is fairly simple, although it does not eliminate the need for someone who truly understands the pre-treatment process to be available during production, in case something needs to be dialed in again – since most brands / styles / colors require varying levels of pre-treatment to be applied, the machine would need to be re-adjusted on a fairly frequent basis.
Once the machine is dialed in for a particular garment style or color, it becomes a simple process to just load the shirt, close the drawer and press the “GO” button – in fact, you could almost hire anyone to perform this step over and over again, as long as the person who was actually dialing in the machine knew what they were doing (I would not leave that step to just any random employee, since it will ultimately determine the quality of the prints you will be getting). Before I had even arrived at the shop to inspect the unit, my production manager had already set up the machine, dialed it in and had several employees pretreat some shirts to test it out – the only issue that came up involved one particular employee holding the green “GO” button for an extended period of time, which apparently causes the spray nozzle to get stuck in the back position with the spray coming out full steam ahead… The solution, I am told, is to make sure your employees do not hold the green “GO” button for an extended period of time! Makes sense to me, and we have not had that issue since we became aware of it.
The price range of the ViperONE pre-treatment machine is projected to fall between $3,500-$4,000 – while this may seem rather steep for a secondary piece of equipment, many shops will find the added consistency and quality to be well worth the investment. After thoroughly discussing the price issue with my production manager, we are in agreement that although it seems expensive when you look at the fundamental construction of the machine, the value that it provides our business far exceeds that number and it is well worth the investment, regardless of the build cost – this is an example of a product being worth “well more than the sum total of it’s parts”. As many people who are running their own DTG print shops will tell you, the stress and frustration (not to mention wasted prints and resources) of the manual pre-treatment process, while completely manageable if you put your mind to it and monitor the process closely, is one of the biggest hurdles that stands between them and long term success; if you could remove the headache and stress that this step causes, and ensure that a full run of 100+ dark garments will print the same from the first to the last garment, would that be worth the price tag to your business? For us, the answer is yes.
An automatic pre-treatment machine is not the first thing a startup DTG print shop should be looking into – before you begin to automate this process, you should become an expert by manually applying pre-treatment to hundreds if not thousands of shirts. Without this thorough and fundamental understanding of the way pre-treatment works and what affects the ultimate quality of the print, you will always struggle to make the process work effectively. Additionally, if you are only printing a few dark garments per day, the time and effort involved with setting up the machine and subsequently flushing it out when you are done is simply not worth it; due to the nature of the pre-treatment chemicals used by most DTG ink manufacturers, it is not recommended that you leave anything sitting in the machine overnight.
If you are printing 30+ dark garments per day and feel that you have a decent understanding of the pre-treatment process, you might consider adding an automatic pre-treatment machine to your arsenal – the ViperONE has proven to be a great choice and is allowing us greater confidence in our process from start to finish. Each garment is loaded onto the “platen” and the drawer is manually closed – once you are ready to spray, you simply press the green “GO” button and the nozzle travels across the garment to apply the pre-treatment; the entire process only takes a few seconds, so it is easy to pre-treat 60 shirts per hour without breaking a sweat. If someone were to really hustle on the machine, I wouldn’t be surprised to see 120+ shirts per hour being pre-treated with little difficulty.
Rather than spraying the shirt once, we have found that we get better fluid deposit on the garment when we lower the volume down and press the “GO” button twice, instead of once; we subscribe to the professional painting philosophy that “two light coats are always better than one heavy coat”. By laying down two light passes instead of one, we seem to get smoother pre-treatment results with more consistent fabric penetration – this is especially important when printing on porous cotton (such as standard vs. ring spun), or fleece materials. Additionally, we have not eliminated the “brushing” step that precedes the heat press – after we spray each garment, we quickly brush it down with a high quality Wooster brush, to ensure that fibrillation is minimized.
At the end of the day, we are very happy with the ViperONE automatic pretreater, and our thanks go out to the team at i-Group Technologies, LLC! This device may even allow us to begin offering “pre-pretreated” shirts to some of our local DTG customers, providing them even greater control of their own printing process while they build up the necessary volume to justify the purchase of an automatic machine – we believe the difference in print quality and consistency speaks for itself. As i-Group Technologies, LLC makes this product commercially available, watch for it to appear on one of our product pages for you to purchase for your own DTG print business! Remember, if it doesn’t work for us in our own production facility (www.fusionlogisticsgroup.com), we won’t recommend it!