Back in December of last year I bought myself a 3D printer (Creality K1 Max); undoubtedly the biggest issue with 3D printing is the reliable adhesion of the first print layer.
Even those operating commercial print farms suffer this problem, with many youtubers giving advice on this topic, from the glue concoction, print surface type/temperature etc. The K1 Max has a self-levelling bed, so this should not be at issue.

Having suffered my fair share of first-layer failures, I tried a number of the youtube advice techniques, but with very limited success.
Initially I thought that the purpose of the glue was to act as a release agent once the print was complete, but it is also important for first layer adhesion.

Through experimentation, I noticed that the glue from the glue stick lost its stickiness within a very short time on the heated print bed. On the K1 Max it takes almost 4 minutes from hitting start print until the printer starts printing. During print initialisation, the print head dwells at the front left (for circa 30 seconds) giving enough time (and space) to apply the glue to the print bed moments before the commencement of printing. Otherwise the print could be paused to allow glue application just prior to print commencement.

By using the above technique, I estimate that I have gone from a first layer failure rate of more than 1 in 10 to less than 1 in 20 prints.

I’d be interested to hear from others who might be suffering from first layer adhesion issues – whether applying the glue to the bed as late as possible helps.

 

Two things you can try is a layer of Kapton film. The sticky side goes on the bed. I don't know why it works but it does.

When I absolutely need the print to stick, I use a double sided tape made by 3M. I don't know where you can buy it. I just happen to have a roll and I'm running out fast.

In most cases I don't need to add anything to the bed. I just make sure that the bed is cleaned with isopropyl alcohol and that the first layer is well squished to the bed.

 

I’m reasonably happy with my failure rate at less than 1 in 20 (which mostly occur at the first layer, rather than becoming dislodged later during print). I keep a close eye on the printer to avoid producing a large bird’s nest.

I only wash my print bed with washing-up liquid & tap water; I’ve even been lazy sometimes and got away with no cleaning between prints – so I don’t believe exotic cleaning chemicals are needed to clean between prints.

 

I use a glue stick and have only had 1 first layer failure. But that was when I didn’t wash and redo the glue between prints. I apply before starting the pre-heat.

 

The Creality K1 Max goes through a self-levelling check/adjustment before each print (that takes around 4 minutes), during this time the print bed is heated to the initial layer temperature – which dries out the glue.

I guess if your printer is a model that starts print soon after applying the glue –then you won’t suffer the glue drying I’m suffering on the K1 Max.

Based on my observations, the ideal glue (for use on 3D printers) would be one that retains its stickiness (even at 60⁰C) for an extended period.