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Just realised I never replied back to this but thanks for your help.
This is the second frame I've done with the first not really being my cup of tea so won't be showing it! Few things is I thought I had done enough clear on the first coat but its seem like I haven't. The fork is perfect though. Couple more questions @general_greyharbour can I go over the clear again without sanding with wet and dry once its fully dried. Been over a week now since I done it.
I noticed that the Metallic Montana Golds sit on the frame way way better than the solid colours, which is good but limiting in terms of colours.
Lastly, I've been given a load circa 40 can of Cellulose spray paint, all new unused but from the research I have done the 2K lacquer won't sit well on top of this.. maybe 1K would work better but have you got any advice?
Juice.Bikes-
Quick answer on the clearcoat... you'll need to scuff it first on this instance or the bond will be sub-optimal. Otherwise it'll be like painting on glass... it will be sticky but there'll be no mechanical bond and eventually they could delaminate.
Generally speaking, nitro-cellulose paints don't need to be abraded between coats but on a rattle can clear, deffo scuff.
You're right about product mixing.
Good practice says that you should be using products with suitable solvent relationships.Get yourself some of these if you don't already... TEST PANELS
You should do a couple of these every time you paint... make sure your layers are going to bond well and that your recipes are suitable. Keep notes on the back regarding temperature, number of coats etc. Useful for repairs and also good for your portfolio... more importantly, if you goof, you'll ruin a cheap panel and not someone's bike!One thing that the visual appearance of a finish can't tell you is the strength of the actual bonds... if the bike looks good, that's cool but if the paint flakes off after a summer then you'll have people asking you why.
Extensive testing on panels will help you figure out the combos which work for you.
As you come to paint a greater quantity of colour product you'll come to learn things like... metallics can cover better BUT the caveat is, they show prep marks and imperfections more significantly... on your final image, there are a couple of dings in the metal around the seat tube insertion area... some colours would hide this much better but a silver-like colour such as you've used is going to make a highlight of that!
Good luck with it all.
general_greyharbour
Sounds like you've got enough to be getting yourself stuck in for learning, if nothing else!
In answer to your question on abrasives...
There are no hard and fast rules but the general approach should be to try and get as deep a scratch as you can, without it being so significant that it can be seen when the next product is applied. This scratch depth will vary depending on the products you use... even down to which colour BUT... loosely speaking...
On a steel frame you can key it with p120 and red Scotch.
On a aluminium you can go with p180 and red Scotch.
Be creative with blocks and shaped tools to get into every part of the substrate; if it doesn't have a scratch it it, that's where the bond will be weakest.
You'll know if you've done it properly because every scratch on the bike will be the same depth and have some uniformity. If you can see individual scratches in your key, then they are deeper than your key so you'll need to go deeper than 120, then back up again.
Be mindful of any edges on your hardware of course because you are removing metal.
Wear PPE and all that jazz.
Once you've got your epoxy on, if you're bold, Mirka Goldflex p400 will be excellent but this might be tricky and expensive so you could fare well with p600 too and use this for the step we spoke about earlier.
If you're to paint a silver or a silver like product with lots of mica, you'll need to key to 800 or even 1000 as these types of colour won't hide a 600 grit scratch and will in fact highlight your prep marks.
A good product to invest in here is a dry guide coat powder. Indasa, Mirka, 3m etc all make one... You take your primed bike, and cover it in black dust, then in the process of keying the primer, you'll be removing the black powder... once the powder is removed, the key is uniform and you can stop sanding. A few goes round with the powder and you'll master it. There is a less effective but common DIY method of this whereby you simply dust a splatter of product from a cheap spray can on the primed bike and go about keying.
For a slim budget, you can buy a mouth atomiser and dump paint into it then get finer atomisation without buying an airbrush... takes practice but it works.
Hope that helps.