It's not always the case but, in some circumstances, you might find that the print file you've uploaded to your product isn't suitable for each variation. The main reason for this is the colours of garments you opt for.
Many customers stick to one colour of garment per design, so only one print file is needed, but what if you'd like your design printing on both a black and white t-shirt, for example? The print file you've uploaded for your white t-shirt will not be suitable to be printed on black, so you'll need to assign a different print file for these variants.
To do this, first log-in to your Inkthreadable account and head to your WooCommerce integration page, and click Manage WooCommerce products.
If you scroll to the bottom of this page you'll find the print file that's currently assigned to each of your variants. This can be left as it is - any print files added to your variants will override this file, but the variants that don't have any uploaded will default to this file. Scroll back to the top of the page.
Working from the top of this page you can start adding print files to any variants that require one. The design for this product is black, but since black can't be printed on black we'll need to upload a print file that's a different colour. White will contrast perfectly.
In the Inkthreadable product column, for each variant, there'll be an Upload button under the heading Print files. Click this button and upload the file you'd like to be used when this variant is printed.
Repeat this process for each variant (remember, any variant that doesn't have a file assigned in this way will default to the original print file) and when finished, click the Save button.
Your product will now be updated, and all variants will be printed using the print file you've uploaded.