How To Sublimate A Lunch Bag with DIY Sublimation Tools

Instructions

STEP 1: GET MY FREE LUNCH BAG DESIGNS

First, download my Sublimate a Lunch Bag designs from my free library – look for Design #644. Alternatively, you can use the Save This Project form near the top of this post and the design link will be emailed to you.

In the PNG folder, you’ll find four designs: a Cake pattern, a Cupcakes pattern, a Donut pattern, and a Lemon pattern. I made these designs with the help of AI art generation and adjusted them with image editing software.

The SVG and DXF files contain a pattern for a pressing insert to help shape the lunch bag when sublimating.

TIP: If you’re not sure how to download zip files, go to jennifermaker.com/svgs because the steps are similar for PNGs and Google Docs.

STEP 2: PREPARE YOUR LUNCH BAG DESIGNS

1. Use a ruler to measure the width of the imprint area from side to side.
   NOTE: My files are shaped to match the top design area curve of the bags in my materials list, but the sides and bottom are straight to make sizing easier.
   
2. Then, measure the height from the top of the curve just below the stitches on the sublimation area straight down to the bag’s bottom edge.
   NOTE: For the lunch bags I am using, the width is 11.25” and the height will be 7.5”. I recommend adding about 0.5” to the height (the paper isn’t large enough to add much more!) and 0.75” to the width for your print size as a buffer.
3. While you’re measuring, you might feel a ridge in the middle. That’s where the bag’s bottom comes into the design area when it’s closed, so the lower section is much thicker than the top. I’ll show you how to fix this soon. For now, record the height from the ridge to the bottom of the upper stitches.
   NOTE: Mine is about 5" and the width is the same as the design area.
   
4. Open Google Docs in the Google Chrome web browser on your computer.
   NOTE: You will need a free Google account to use the free Google Docs software.
   TIP: You can also download and open the Google Docs app, but be aware that you won’t be able to install or access any printer profiles from a mobile device, and you’re also limited in features, so I do not recommend it on a mobile device.
5. Click “Blank document” at the top left to open a new document.
   
6. Go to the “File” menu and select “Page setup.”
   
7. Check the box next to “Landscape” to better match the page orientation to the blank.
8. Change your “Margins” to “0” to use more of the page.
9. Change your “Paper Size” to match your sublimation paper size.
   NOTE: I’m using 8.5” x 14” or legal-size paper.
   
10. Click “OK” to apply the settings.
11. Go to the “Insert” menu, select “Image,” and select “Upload from Computer.”
12. Select the sublimation design you want to use.
    TIP: It’s probably in your “Downloads” folder.
13. Click “Open.”
    
    NOTE: The image may not appear at the correct size, but that’s ok.
14. Click the area that says “Untitled document” at the top and type a name for the file.
    TIP: Google Docs automatically saves your progress.
15. To resize the design, right-click the image and select “Image Options.”
16. Select “Size & Rotation.”
17. Keep the “Lock aspect ratio” box checked to maintain the design’s proportions and change the “Width” field to the measurement you recorded when measuring the lunch bag. The “Height” will automatically adjust proportionately.
    NOTE: For the lunch bags I am using, the width is 12” and the height will be about 8” with an all-over design. If you’re using a design without a background, make it 9” x 6” or smaller so it’s easy to center on the bag.
    
18. Click the image and select the “Wrap text” icon from the menu that appears below it.
    
19. Click and drag the image to the center of your page, as that ensures it won’t get cut off at the edges and you have plenty of space to trim the edges.
20. Go to the “File” menu and choose “Print.”
21. Select your sublimation printer under “Destination.”
    NOTE: If you want to decorate both sides of the lunch bag, change the “Copies” to “2.”
22. Click the arrow beside “More Settings” and select “Print Using System Dialog.”
    
23. Your options may look different - just make sure the sublimation printer is selected, that you “flip horizontally”, and select the highest quality matte paper setting.
    
24. Load sublimation paper correctly into your sublimation printer.
    NOTE: Check the packaging for information on how to load the paper.
25. Click “Print.”
26. Allow the prints to dry before handling them, as the ink can smear.
    NOTE: The printed design will appear lighter before pressing.
    
    

STEP 3: PREPARE YOUR SHAPED PRESSING SUPPLIES

NOTE: Using the pressing pillow and cardboard insert together will help ensure an overall even press by keeping the neoprene in the correct shape for a flat press.

MAKE A PRESSING PILLOW

1. Make sure the lunch bag has the zipper open but is closed correctly so the bottom is folded up and inside the lower section.
2. Place the bag flat on your work surface.
3. Check your measurements for the thin section in the bag.
   NOTE: My measurements were 11.25” wide and five inches tall for the thin area.
4. The pillow needs to be a bit smaller side-to-side so it can slip into place, so mark a rectangle the same height but about 0.75" thinner side-to-side on the cotton batting with a ruler and marker.
   NOTE: I made a 10.5” by 5” rectangle.
5. Cut the rectangle out with scissors.
   TIP: This doesn’t have to be perfect or pretty!
   
6. Insert the batting into the lunch bag to the ridge of the folded-in bottom.
   NOTE: Some of the batting will extend past the shaped top of the design area, which is ok.
7. If the ridge is still noticeable, add matching layers of cotton batting until they are even with the edge of the fold.
   NOTE: I used three layers.
8. Remove the layers of batting and stack them on a piece of teflon.
   
9. Wrap the teflon around the cotton and staple the three open edges as close to the batting as possible.
   
10. Use scissors to trim the excess teflon close to the staples to finish the pillow.
    
11. Re-insert the pressing pillow into the flat bag so that it sits against the ridge of the folded bottom to form a smooth surface from the zipper to the bottom edge.
    

MAKE A SOLID PRESSING INSERT

NOTE: SVG and DXF files are provided and can be used if you choose to cut cardboard on a cutting machine. See my tutorial on cutting cardboard with a Cricut for more information.

1. Download and open the free version of Adobe Acrobat Reader.
   
2. Open the “template” PDF.
3. Click “File” and select “Print.”
   
4. In the Print menu, select your normal printer, not the sublimation printer.
   NOTE: Your settings may look slightly different than mine depending on your computer and printer, but use my choices as a guide.
5. For “Size” select “Actual Size” so the template will fit the bag.
   
6. Click “Page Setup” and next to “Paper size” select 8.5” x 14” or legal size paper.
   
7. Click “OK.”
8. Make sure you have legal size copy paper loaded correctly into your printer and click “Print.”
9. Use scissors to cut the printed template along the lines.
   
10. Use a marker to trace the template on a piece of cardboard.
    
11. Use scissors to cut the cardboard to the right shape.
    
12. With the pressing pillow still in the lunch bag, put the solid insert inside ABOVE the bag’s folded bottom so it reaches the corners and stops just below the zipper, creating a smooth sublimation surface.
    
    NOTE: If your lunch bag has sewn details at the edges, try to adjust them to be consistently flat with the sublimation surface (you can sublimate over them, the ink may just be a little inconsistent where the details make the bag textured) or move them to the curve to avoid them.
    
    
    

STEP 4: SUBLIMATE YOUR LUNCH BAG

IMPORTANT: As with all sublimation projects, turn on a fan and open a window to improve your ventilation before beginning.

1. Pull out the paper trimmer’s guide extension.
   NOTE: You can also use scissors.
2. Place the printed images face up so the lower edge of the design is along the cutting line.
   NOTE: If your design doesn’t have solid edges, roughly align the element edge you can see and the result will be within the buffer area we added to the sizing.
3. Press the paper’s long edge up against the top guide to make sure the cut will be straight.
   
4. Hold the paper in place and lower the fold-down ruler with the blade onto your material.
   NOTE: You can press down on the ruler to keep the material in position, just don’t get close to the blade.
5. Use your other hand to press and drag down on the blade and draw it down the straight line in a smooth motion.
   
6. Use the paper trimmer to remove the white space on the other two straight sides of the design.
   
7. Use scissors to trim along the curved top to remove the last of the white space.
   
8. Turn on the Autopress and set it to 400°F / 204°C for a 10 second preheat.
   TIP: If you’re using a different heating method, see my Sublimation Cookbook for additional details.
9. Place a piece of white cardstock onto the pressing mat.
   
10. Place the neoprene lunch bag onto the cardstock with the pressing pillow closer to the work surface and the cardboard insert above it, making sure the sublimation surface is even.
    
11. Use a lint roller to clean the surface of the lunch bag.
12. Place a piece of white uncoated butcher paper over the lunch bag and preheat it for 10 seconds with light pressure to remove wrinkles and moisture, then let it cool.
    NOTE: The bag may appear to bubble upward in spots after heat is applied. This is normal with neoprene and will go away as it cools.
    
13. Remove the butcher paper.
14. Gently bring the print’s sides together to make a very small crease (avoid the ink) at the middle of the top edge.
    
15. Place the trimmed print face down onto the lunch bag making sure the design’s curve fits just below the stitched seam where the zipper is and the middle crease is centered below the handle.
16. Use several pieces of heat resistant tape to secure the print’s upper curved edge to the bag.
    
    NOTE: The tape might not want to stick to the fabric’s surface due to the texture, so use a few pieces and press them down well.
17. Smooth the design tightly to the bag straight down, then use a piece of heat resistant tape to secure the paper’s bottom edge to the uppermost folded section of the blank.
    
18. Smooth the design out from the middle to one short side edge and add a piece of heat resistant tape to curve the design around the edge and secure it to the neoprene fabric.
    
19. Repeat for the other short edge.
    NOTE: Some of the paper’s bottom corners won’t touch the bag because of its curved bottom when folded, but the overhanging design will make sure your pattern covers the sublimation area. Make sure there is protective white cardstock under the entire bag and design to protect your pressing area from ink during sublimation pressing.
20. Place a piece of white uncoated butcher paper large enough that you can safely hold the edges down with your hands away from the heat source over the lunch bag and design.
21. Keep the press at 400°F / 204°C and set the timer to 60 seconds for pressing the first side.
22. Press over the protected lunch bag and when the time is nearly up, grasp the butcher paper by the edges and hold it down to keep pressure on the bag and design BEFORE the press automatically opens..
    
23. When the time is up, hold the butcher paper down for about a minute in case the neoprene puffed up so that the surface and ink can settle without moving.
    NOTE: The press will be hot, so keep your hands away from the edges.
24. Hold the paper and bag in place for a minute to cool, then remove the papers to reveal the finished surface.
    
25. Allow the bag to cool.
26. Flip the bag over.
27. Remove the cardboard insert and slide it into the bag on the other side of the pressing pillow to make the undecorated surface smooth.
28. Repeat the Steps 1-25 to sublimate the second side using fresh protective cardstock and butcher paper to avoid transferring excess ink.
    

STEP 5: SHOW IT OFF

Here are my finished lunch bags!