Applying a Template to a Product
Generate real mockups for a specific product and design by combining a saved template with a new design graphic.
Overview
Once you've created a mockup template, applying it to a product is the core workflow for generating variant-specific mockups. You combine a saved template (which defines colors, base mockups, and placement) with a new design graphic to produce composite mockup images for each color variant.
This process happens entirely within PrntFlow and results in new images being uploaded to your Shopify product media and assigned to the correct variants automatically.
Step-by-Step: Upload Product Mockups Workflow
Select a Product
Use the product search box to select a Shopify t-shirt product from your store. The product should have color variants to take advantage of PrntFlow's per-color mockup generation.
Tip: If you navigate to this screen from the "Products without mockups" view on the Dashboard, a product may already be pre-selected for you, saving a step.
Select a Template
Choose a saved template from the dropdown menu. The template defines which colors are available, which base mockup image belongs to each color, light/dark shirt groupings (if configured), and how your design should be placed and rendered.
If you've set a default template in Manage Templates, it will be pre-selected automatically to speed up your workflow.
Note: If you haven't created any templates yet, the UI will prompt you to create one first before you can proceed with uploading mockups.
Upload Your Design Graphic(s)
Upload the design graphic you want to appear on your t-shirt mockups. PrntFlow uses a two-slot system to handle different color groups:
Slot A (Required)
This is the default graphic used for all colors, or specifically for dark-colored shirts if your template has light/dark color groupings configured.
You must upload at least one graphic to Slot A to proceed with mockup generation.
Slot B (Optional)
If your template has light/dark color groupings configured, you can upload a different graphic to Slot B for light-colored shirts. This is useful when you need light text on dark shirts and dark text on light shirts.
If Slot B is left empty, all colors will use the Slot A graphic regardless of grouping.
Supported formats: PNG, JPG, WEBP, AVIF
Maximum file size: ~50 MB per graphic
Dimension warning: If your uploaded graphic's dimensions differ significantly from the test graphic used when creating the template, PrntFlow will show a warning that placement might not be exact. You can still proceed, but you may want to adjust the template or resize your graphic for best results.
Generate Mockups
Once you've selected a product, chosen a template, and uploaded your design graphic(s), click the "Generate Mockups" button to start the process.
PrntFlow will composite your design onto each color's base mockup using the placement and settings from the template, then upload the generated images to Shopify and assign them to the correct variants.
Progress Indicators:
You'll see real-time progress as PrntFlow works:
- • Rendering mockups X/Y – Compositing your design onto base mockups
- • Uploading mockups X/Y – Uploading generated images to Shopify's Product Media API
- • Success toast – Confirmation message when all mockups are uploaded and assigned
On success, a "View Product" button will appear, linking directly to the Shopify product page in your admin so you can review the newly uploaded mockups and variant assignments immediately.
What You'll See in Shopify
After PrntFlow finishes generating and uploading mockups:
New Images in Product Media
The generated mockup images appear in the product's media gallery in your Shopify admin, just like any other product image.
Variants Associated with the Right Mockup
Each color variant is automatically associated with its corresponding mockup image. When a customer selects a color on your product page, they'll see the correct mockup for that color.
Troubleshooting & Edge Cases
What if the template has colors the product doesn't?
Those extra colors are simply skipped during generation. PrntFlow only generates mockups for colors that exist in both the template and the selected product. For example, if your template includes Black, White, Red, and Yam, but the product only has Black and White, PrntFlow will generate mockups for Black and White only.
What if the product has colors the template doesn't cover?
Those product variants won't receive new mockups from PrntFlow during this upload. They'll keep their existing media (if any). If you want mockups for those additional colors, you'll need to create or update a template that includes them.
What happens if I hit the hourly upload limit?
The Launch plan includes a 1 GB per hour upload quota for generated mockup images. This quota covers both the base mockups you upload when creating templates and the composite mockup images PrntFlow generates when applying templates.
If generating a batch of mockups would exceed your hourly limit, PrntFlow will reject the upload before processing and show an error message like: "Hourly upload limit reached. You can upload 1GB per hour on the Launch plan." You can wait for the quota to reset (at the top of each hour) or optimize your mockup file sizes to fit within the limit.
What if Shopify rejects an image for being over 20 MB?
Shopify has a hard limit of 20 MB per product image. If PrntFlow generates a mockup that exceeds this limit, the app will warn you and offer to retry the upload as a JPG at reduced quality.
If even the reduced-quality JPG is still too large, PrntFlow will show a fatal error message indicating that the mockup cannot be uploaded at that size. In this case, you'll need to use smaller base mockup images or lower-resolution design graphics when creating your template.
Are existing product images deleted?
No. PrntFlow only adds new images and links them to variants. It does not delete any existing product media. When you generate mockups, the new images are uploaded to your Shopify product media gallery and assigned to the appropriate color variants. Your existing images remain in Shopify unless you manually delete them. Even if you uninstall PrntFlow, all mockup images it generated will stay in your Shopify store.
Can I regenerate mockups if I change my design?
Yes. You can apply the same template to the same product as many times as you want with different design graphics. Each time, PrntFlow will generate new mockup images and upload them to Shopify. You can manually remove old mockups from the product media gallery in Shopify if you no longer need them.