If you have extensive experience with a specific printer model and you've been happy with the print results there, it can sometimes be a little jarring moving to a different printer model. It's difficult to exactly replicate print performance between two different printer models, especially when moving from inkjet to laser or vice versa. With that being said, there are a few additional steps to try that may improve the print quality with the HP Color LaserJet Pro M454dw.
It sounds like you're already using appropriate paper type settings for the weatherproof polyester laser material. I haven't used the HP Color LaserJet Pro M454dw, but I have a couple similar HP models available and I've never felt the need to move up to the heavyweight designation when using this material. I typically stick to one of the standard photo or glossy material types, but labels or heavyweight glossy should definitely work as well.
There are a couple of more advanced troubleshooting techniques that you can use that may improve your print results. These are detailed in the manual for the printer model, which I've linked to below:HP Color LaserJet Pro M454dw Manual
You're going to want to take a look at the "Troubleshoot Print Quality" section that starts on page 105. There is a pretty expansive selection of troubleshooting methods detailed in this section, but based on your the feedback you've provided I'd recommend looking at:
- Calibrate the printer to align the colors (page 111)
- Print and interpret the print quality page (page 111-112)
- Check the EconoMode settings (page 112-113)
- Adjust print density (page 113)
The whole section is worth skimming through, as there may be some other suggestions that are applicable, but the topics listed above seem like they'd be the best to focus on initially.
I hope this helps. If you need any additional information please just let us know.