# HELP - How do I prevent shiny box when pressing vinyl on 100% poly dri-fit shirts?



## embprints (Sep 13, 2016)

Hello,
I have to do some names on the back of 100% polyester dri-fit shirts
and even though I have Chemica Hotmark Revolution vinyl that can press as low as 230 F with recommended medium pressure, 
I'm still getting a very faint shine where I pressed them (using a heat press pillow too). I did a test wash to test the vinyl since first time using this brand and it shiny box is still there!

Any ideas?

Siser tech support (when I used easyweed on the last order that used 100% poly) suggested that I do a press of the WHOLE shirt to remove the first shiny box! 

BTW, I still do a 2-3 sec pre-press on the 100% polyester shirts to remove moisture? That is when the first shiny box appears.

Thank you so much!


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## pmzirkle (Oct 5, 2014)

There is no need to prepress poly shirts. They do not trap moisture.


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## Dekzion (May 18, 2015)

pmzirkle said:


> There is no need to prepress poly shirts. They do not trap moisture.


I beg to differ there.
they may not in CA but in the UK it is a must to pre-heat them to remove moisture.
Pressing the whole shirt is the way to go.
They end up a lot better presentation wise as well when neatly pressed.


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## embprints (Sep 13, 2016)

Dekzion said:


> I beg to differ there.
> they may not in CA but in the UK it is a must to pre-heat them to remove moisture.
> Pressing the whole shirt is the way to go.
> They end up a lot better presentation wise as well when neatly pressed.


Thanks for the reply.

I live very close to ocean water, so I may need to still pre-heat the 100% polyester shirts then...but I will try it without closing my heat press completely?

Do you press the whole shirt before or after applying the vinyl? When doing this to 100 % polyester shirts, aren't lines left on the shirt where you overlapped when pressing different sections? (my press is just 15"x15")


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## embprints (Sep 13, 2016)

pmzirkle said:


> There is no need to prepress poly shirts. They do not trap moisture.


Thanks for the reply.

Hmm...that makes sense especially since they are Dri-Fit. I live near the ocean in California and now that it's winter the air seems very moist, do you think preheating or pre-pressing would be unnecessary still?


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## splathead (Dec 4, 2005)

I'm surprised you're still getting a shine at 230F. What color shirt? What brand?


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## embprints (Sep 13, 2016)

splathead said:


> I'm surprised you're still getting a shine at 230F. What color shirt? What brand?


Thanks for viewing my post and for the reply.

*Photo attached

Yeah, I'm very surprised too. I did a lot of research in this forum before I did any pressing and before posting this question, and many people were able to press at 300+ F with no issue.

Right now dark/forest green 100% polyester from Eastbay.com is what I am testing on. Last week pressed on dark green Nike 100% Poly Dri-Fit tank top singlets at 265 using Easyweed, per Siser Tech support's instructions. Tomorrow will be pressing names on the back of dark green Nike 100% Poly Dri-Fit long sleeve performance shirts called "The Nike Tee" from Eastbay.com using Chemica Hotmark Revolution vinyl which is meant to be used on heat sensitive materials at 230-245 F and medium to high pressure.

BTW, I do a 2-4 second prepress (at 230-245 F) to remove moisture, and the box already shows...but I assume this first box is just caused by the moisture leaving.

Washing, rubbing, or lint brush didn't remove the box from the completed singlets or from pressed test shirt.

I've started using a rough/textured teflon sheet instead of parchment paper or smooth teflon sheet. And Ive set my pressure to just being considered medium pressure...so when I do my pressure calibration using a half sheet of paper, it might still slide out, if I pull hard enough or I turn my pressure knob to the right by half a turn. The rough teflon and just enough pressure, seemed to help a little.

The shirts are provided by the local high school (dark green is one of their school colors) who we recently became a vendor for, and now their athletic director is giving us all their business..so far. They aren't as picky as their school clubs, since they just need the team shirts done fast, but I take pride in what I do and what I give my clients.

***BUT today, about an hour ago, I think I figured a solution to remove the shiny faded box....home iron! I came across an old posting in this forum that suggested it, so I tried it out, and so far so good. I basically set my home iron to 280-320 and just "blend" away the shiny box lines.

I have attached a file show a test I did this morning using the iron. Hopefully, you can see the box on the left clearly. Its more noticeable in person. I will wash this tomorrow morning after 24 hrs, to make sure my temp and pressure settings are good enough for the vinyl, and to see if the box returns. I haven't tested on the shirts the school gave me because they are about $30 each and they had the company screen print the school logo on the front. For now, I am going to just do my best to minimize the shine, and pray that the iron will "erase" it away.

BUT my original question still is...how do I prevent this shiny/faded box?


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## Dekzion (May 18, 2015)

dark colour shirts are notorious for changing colour when heated, that's probably why you are 'blending' the colours with a hot iron,you're changing the rest of the shirt colouring too.


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## embprints (Sep 13, 2016)

Dekzion said:


> dark colour shirts are notorious for changing colour when heated, that's probably why you are 'blending' the colours with a hot iron,you're changing the rest of the shirt colouring too.


Thanks for the reply!

So this means that there is not much more I can do to prevent the shiny/faded box since Im pressing on dark colored 100% polyester shirts?

Now that I think about it, many of the posts I found here talking about 
pressing on 100% polyester at 300 F successfully,may have been from the sublimation section which means they used white poly shirts. And the ones who did press vinyl at 300+ F may have been light colored shirts too. The rest just didn't find a solution.

At least I know that this may be common for dark colored shirts. I was starting to think its user error or that my temperature readings on the heat press are way off. Ive been doing temp tests on my press for the past two days using an analog meat probe, a digital meat probe, a brand new Weber bbq grill temp probe and an IR gun. My IR gun readings are 10 deg F different from the heat probes...so I was worried my temp was too high. but even at 230 F, if my reading was 10-15 deg off, I should still be in a safe range for 100% poly....yet I still get the shine box.

Siser tech support even suggested heat pressing the whole shirt to get rid of the shiny box....but I havent tried that because I have a 15"x15" heat press so I will have to press the shirt in sections, and that can add lines all over the shirt where I would have to overlap.


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## tfike (May 2, 2011)

I live in Pennsylvania and our poly shirts retain some moisture, I guess that's just a California thing. I think moisture causes cancer out there just like everything else. LOL Another reason you could still be getting that shine is because when you're pressing the shirt you're crushing the polyester fibers. I've been told that a lot of the moisture wicking fabrics, the fibers are actually hollow tubes and when you press the shirt you flatten those tubes out and that can cause it to have that shiny look.


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## splathead (Dec 4, 2005)

embprints said:


> pressing on 100% polyester at 300 F successfully,may have been from the sublimation section which means they used white poly shirts. And the ones who did press vinyl at 300+ F may have been light colored shirts too. The rest just didn't find a solution.


Sublimation is pressed a lot hotter than 300F. It's not that shine doesn't happen on white garments, its that it's white so you can't see it. We have no qualms sublimating white polyester at 374-400F. But any other color, forget it.

We routinely press vinyl at 300 on dark polyester and rarely experience the shine. Every once in a while we may get an edge of platen line, but it's hardly noticeable. 

I just looked at 10 personal dark poly shirts I've pressed on Nike, Under Armor and Sanmar and none have shine or lines. I'm thinking what you do see washes away after a while. 

One thing we do that it looks like you are not is we place the the entire shirt on the platen. So any lines/shine we have is 16X20 inches (size of press) . If that makes sense. If you're using pillows, use one the same size as your press.


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## embprints (Sep 13, 2016)

splathead said:


> Sublimation is pressed a lot hotter than 300F. It's not that shine doesn't happen on white garments, its that it's white so you can't see it. We have no qualms sublimating white polyester at 374-400F. But any other color, forget it.
> 
> We routinely press vinyl at 300 on dark polyester and rarely experience the shine. Every once in a while we may get an edge of platen line, but it's hardly noticeable.
> 
> ...



Thanks for the reply!

I think you hit it right on the nose when you said that you press the whole shirt when pressing. Siser tech support suggested something similar but to remove lines. I have a 15x15 inch clamshell, so it could work on most of the shirt sizes the high school students wear. I just didnt do it because most of the posts here said to minimize contact with the shirt and suggested using a small pillow. I think I tried it once without a large pillow or threading the shirt through the platen and the seams on the back of the shirt caused shiny lines on the front of the shirt that I was pressing the design on.

Do you still use a pillow to deal with the seams? 

I started using a 10x10 pillow I made for the first batch of 100% poly shirts I did last week, but if its just better to press the whole shirt like I normally do with cotton shirts, then I will go back to doing that!

Do you thread your shirt onto the platen or just lay the whole shirt on top or use a pillow?

Thanks!


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## embprints (Sep 13, 2016)

tfike said:


> I live in Pennsylvania and our poly shirts retain some moisture, I guess that's just a California thing. I think moisture causes cancer out there just like everything else. LOL Another reason you could still be getting that shine is because when you're pressing the shirt you're crushing the polyester fibers. I've been told that a lot of the moisture wicking fabrics, the fibers are actually hollow tubes and when you press the shirt you flatten those tubes out and that can cause it to have that shiny look.


Thanks for the reply!

I live in Northern California, 20 minute walk from the ocean/bay water, so the air is full of moisture here, so I plan to still do a prepress to remove the moisture. When I prepress cotton shirts, I press for 5 secs, air out the steam, then another 5 secs, or else I wont get all the moisture out!

As for cancer, in our area its probably caused by the oil refineries not far from here or the fact that some housing communities were built on top of old land fills/ garbage dumps.

The crushing of the polyester fibers makes sense. Im trying to do the minimum amount of pressure needed on the 100% poly shirts. I plan to test wash on a test shirt tomorrow morning ( 24 hr wait) to make sure that the temp and barely medium pressure settings I did this morning will be good enough to prevent the vinyl from peeling off.


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## splathead (Dec 4, 2005)

embprints said:


> Do you thread your shirt onto the platen or just lay the whole shirt on top or use a pillow?


No I definitely thread. Both for poly and cotton. Otherwise, even on a t-shirt, you'll get a collar impression on the back of the shirt.

We always use a 16X20 pillow on our 16X20 press when doing polyester. It eliminates hard platen edge press lines on the shirt. And it at least disperses any press shine to the outer edges of the shirt, away from the design, making it that much less noticeable. 

Free tip: For those of you who don't have a threadable press, having a pillow the same size as your press allows you to thread your garment directly on the pillow which serves the same purpose as a threadable press.


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## Dekzion (May 18, 2015)

Agree with that Joe, I also use table top protector, the stuff with fibre (which happens to be polyester) one side and the brown solid back as an insert if I need to go near seams as it just lifts the shirt above them. it's also cheap enough to chop into smaller sizes to lift logo's clear. Tiles and slates bed into it by the way taking the print round the edges.


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## embprints (Sep 13, 2016)

splathead said:


> No I definitely thread. Both for poly and cotton. Otherwise, even on a t-shirt, you'll get a collar impression on the back of the shirt.
> 
> We always use a 16X20 pillow on our 16X20 press when doing polyester. It eliminates hard platen edge press lines on the shirt. And it at least disperses any press shine to the outer edges of the shirt, away from the design, making it that much less noticeable.
> 
> Free tip: For those of you who don't have a threadable press, having a pillow the same size as your press allows you to thread your garment directly on the pillow which serves the same purpose as a threadable press.


Thanks for the great info!

I am going to make a 15x15 pillow today (since I plan to start pressing these shirts tomorrow), and try it out since my press is not threadable unless the shirt is very large or the design is close to one end of the shirt.

Btw, heat press pillow are kind of soft Or are they firm but with a little bit of "give"? I've seen some made using high density upholstery foam on youtube. The ones Ive made recently are made out of teflon sheets with foam placemats in the middle. 

Do pillows cause issues when it comes to pressure requirements?(Easyweed Stretch needs heavy pressure)

Thank you again!


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## embprints (Sep 13, 2016)

Dekzion said:


> Agree with that Joe, I also use table top protector, the stuff with fibre (which happens to be polyester) one side and the brown solid back as an insert if I need to go near seams as it just lifts the shirt above them. it's also cheap enough to chop into smaller sizes to lift logo's clear. Tiles and slates bed into it by the way taking the print round the edges.


Thanks for the reply! That's really interesting. I'll check out some table top protectors. Thanks!


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## splathead (Dec 4, 2005)

embprints said:


> Thanks for the great info!
> 
> I am going to make a 15x15 pillow today


Since you make your own, no law against making one bigger than your press. Try a 16X16 or a 16X20. Much easier to thread larger shirts on your pillow that way.

My next pillow purchase will be larger than 16X20 if I can find one. 

Pillows usually start off kinda hard but gets soft over time with use. 

You can adjust pressure to anything you like while still using a pillow.


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## embprints (Sep 13, 2016)

splathead said:


> Since you make your own, no law against making one bigger than your press. Try a 16X16 or a 16X20. Much easier to thread larger shirts on your pillow that way.
> 
> My next pillow purchase will be larger than 16X20 if I can find one.
> 
> ...


Oh, I wouldn't have thought about making one larger than my press!

Because my current pillows were made with a stack of placemats in the middle, Ive noticed that they have become firmer after a day or two of use of many pressings. The pressure and the heat seems to be compressing the foam. lol Im thinking of using fabric from some old XXL and 3XL shirts as "filling" for my new pillow, with maybe a thin flat board in the middle or maybe at its base so its not so flimsy or too soft.

Thank you Splathead and everyone for the great replies and info! 


I'm so grateful & glad I found this forum a little over a year ago. My business has grown so much since then, and you guys have been there for me whenever I had questions or issues!


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## into the T (Aug 22, 2015)

embprints said:


> Thank you Splathead and everyone for the great replies and info!
> 
> 
> I'm so grateful & glad I found this forum a little over a year ago. My business has grown so much since then, and you guys have been there for me whenever I had questions or issues!


i agree, many good posters here

it's been a great knowledge resource


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## Lees Custom (Mar 1, 2013)

I have found this almost unavoidable on some brands when sublimating at 390* which is significantly higher than what you are doing. I also have seen it happen when doing vinyl like you are talking about which is one of the reasons I do not print on garments brought in by people that are 100% Poly.

However, I never press the entire shirt, nor do I use a pillow larger than my press. I have found when I do and my pressure is too high, I get an actual indent in the fabric as only the part under the press is subject to heat and pressure.

If it is just a shiny box, I would tend to think your pressure isn't too high, but it is more the direct contact to the platen. You can try covering it with white craft/butcher paper or a Flexible Application Pad from Stahl's. If the paper isn't bleached white, it may stain a white shirt. I do this when sublimating and it works rather well and keeps the dye off the pres to avoid it getting on other garments. Not sure how many times you can reuse the craft paper as I throw it out after one print. It does tend to burn and get brittle, so I would just chuck it. It is cheap any way.

With the flexible application pad, increase temp 10* or time 8 seconds as the pad will affect the print if you don't. I would also increase the pressure either +5 or about a half turn of the knob. Also, when you peel it off the shirt, it will be rather hot as it holds the temperature as it is basically thin rubber.

Teflon sheets in my experience will still give you the shine, so I would avoid them unless you put craft paper under it.

Hope you find a resolution to the issue that works for you! In my experience, and from talking to local colleagues there seems to be various ways to get around that issue.


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## splathead (Dec 4, 2005)

embprints said:


> Because my current pillows were made with a stack of placemats in the middle, Ive noticed that they have become firmer after a day or two of use of many pressings. The pressure and the heat seems to be compressing the foam. lol Im thinking of using fabric from some old XXL and 3XL shirts as "filling" for my new pillow, with maybe a thin flat board in the middle or maybe at its base so its not so flimsy or too soft.


You may want to invest in one from one of the heat press suppliers. I would think yours could get hard & lumpy pretty quick. Lumpy will cause the vinyl not to stick completely. Hardness increases the likelihood of press shine.

Commercial pillows use a solid piece of heat resistant foam and the pillow 'case' are 2 teflon sheets sewn together. They cost $25-$30 for a 16X20.


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## Dekzion (May 18, 2015)

Garden swing and chair seats are usually filled with polyester fibre.


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## PolyPains (Aug 21, 2021)

Hey guys so has a clear solution been figured out here? I'm having the same problem.


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## DrivingZiggy (Apr 24, 2017)

Suggestions for Polyester Shirts?


Having the typical frustrations of heat pressing on Polyester. Generally always happens on any but I like the Sport Tek posicharge but usually have scortching marks where the platen area leaves a glossy square. Yes, I've lowered the temp. This will happen even at around 250 which tells me maybe...




www.t-shirtforums.com


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## PolyPains (Aug 21, 2021)

DrivingZiggy said:


> Suggestions for Polyester Shirts?
> 
> 
> Having the typical frustrations of heat pressing on Polyester. Generally always happens on any but I like the Sport Tek posicharge but usually have scortching marks where the platen area leaves a glossy square. Yes, I've lowered the temp. This will happen even at around 250 which tells me maybe...
> ...


That's my other thread. Was hoping for more insight.


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## DrivingZiggy (Apr 24, 2017)

D'oh! Got me with the multiple threads asking the same question.


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