I have not seen many reports - actually rather none? - on hydro dipping a deck followed by glass frit on this forum, so I would like to share my experience here with you in some greater detail. I hope I will not be too redundant though, but since I have hardly any prior experience and/or knowledge of the whole process this may happen at times. It took me about 1 month to complete the deck, but I have been mostly working on the weekends. However, obtaining all the required materials took about another 1-2 months prior to starting, but I am sure that you can do it much quicker ;-).
The hydro dipping instructions, i.e. points 1-11, follow a basic protocol from company (MST Design). There may be better protocols out there and some of the steps detailed below may be unneccesary or even wrong; up to you to correct me on this 
.
Shout out to @Briman and @Sender who got me trying.
Here are some pics on the end product and its many flaws. Overall, however, I am rather happy with it.
Here’s what I did:
- Sand the deck
(I don’t remember with what paper I did that, but probably it does not matter much though; looks like I used 240 or something like that)
-
Clean the deck with a silicon remover
(Work with gloves after this step to avoid adding lipids et cetera) -
Apply a primer
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Spray paint the deck (2x; usually white)
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Fill and prepare your water bath at 25-30°C
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Cut your hydro film
- Place your hydro film (with the sticky side pointing down) in the water bath
This may well be the most tricky part, in particular if your working alone. Holding the film diagonally helps to avoid bubbles when placing the film onto the water surface. Wait for 90 seconds after placing the film on the water surface.
- Spray the activator on the hydro film
The film becomes noticeable shiny/reflective after spraying the activator. Wait about 15 seconds.
- Dip your deck
Go slowly on this from back to front or vice versa and at an angle of about 45°.
( sorry for the terrible picture
)
- Wash off gently any non-attached remaining film rests under warm running tap water
Be careful with this. If your foil is not well attached you may damage it, at least it happened to me a couple of times.
All the white spots on the deck are places where the film did not attach well, i.e. mistakes. I would say quite a lot!
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Let the deck dry for at least 12 hours (overnight)
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Apply 2K clear coat (4x)
I did not want to destroy the hydro film with the sanding later. Thus, I decided to spray 4 times 2K clear coat on the deck. 1 time = 1 can of 2K clear coat (not cheep).
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Sand the deck with 800-1200 paper (thanks @Sender and @Briman!)
I don’t remember exactly but I think I used 1200 or 800 paper. Since I put enough clear coat in step 12 it did not damage the design of the hydro film at all. To me that was the most crucial step. -
Apply epoxy coat (4x)
I applied 4 times the epoxy coat and sanded the board with 400 paper in between before the glass frit. I never worked with epoxy before and had no idea that it will harden the paint brush over night too! Thus you either need many paint brushes or, alternatively, just wrap you paint brush tightly in some gloves for example and put it in the freezer. This way you can reuse it the next day. Much better in my opinion!
I had many flies etc sticking to my deck, since I was working outside
… at least, as a novice, that gave me an idea that chances were that the glass frit may stick too
(The best way to get your epoxy out from your calibrated cylinder? Just let it stick!)
- Sand the deck with 400 paper
- Repeat steps 14-15 four times
- Apply a 5th layer of epoxy and apply glass frit
(3 pictures above are just after adding the glass frit)
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Apply 1 layer of epoxy over the glass frit
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Sand the deck with 400 paper
If you work more carefully than me you can probably avoid that step. However, I had lots of epoxy running down the side of my deck which resulted in largely uneven surfaces on the sides and underneath. I therefore had to sand everything except the top of the deck again to make it smooth!
I even sprayed the whole roadside again in blue 2 times.
- Apply 1-2 coats of 2K clear coat
Done.
Pictures of the final results are depicted on the top of this post.
PS: And now begins the build …