Liphook wrote: ↑Thu Feb 15, 2024 3:58 pm
Fine work indeed Rockape! Did you spray /bake that external paintwork? I'd be interested to know your material choices and techniques used, provided of course that's not giving your restoration secrets away
Of course Liphook, no problem.
First of all, all my (few so far) restorations are an unknown from a durability and longevity point of view; hopefully they will hold up, but only time will tell?
They say preparation is everything (and it is!), so I spend some considerable time getting every speck of the original finish off the metalwork, which is mainly with 600 grit wet and dry and a LOT of elbow grease followed by 1500 to 2000 grit paper.
As you probably know Mitchell paint is pretty tough stuff, impervious to paint strippers and extreme heat, so it is always a painful job!.
Once I have the metalwork prepared, I clean thoroughly with isopropyl alcohol, and using rubber gloves, mask off and mount the part for clear access to all areas (I use a block of hard foam packing with cotton buds to hold the body; a large zip tie and cotton buds to support around it, through the rotor shaft hole. The side plate is mounted on a wooden block (as described later).
I then apply a couple of coats of Upol Acid 8 etch primer from Halfords, then clear out the paint in the Mitchell script using a scribe from a watchmakers screwdriver set (I do this a couple of hours after spraying, while it is still slightly soft to prevent it from chipping around the grooves. Etch primer will not adhere to paint, so that is why my metalwork is always completely old-paint free before spraying.
The next stage after a few hours drying time is the Halfords red primer sealer coat (I try to keep this as thin a coat as possible), then etch out the script again (scary stuff!).
Sand lightly with 2000 grit wet and dry for a smooth surface for the final top coat (avoid sanding any edges, unless you really have to)
The Halfords rattle can paint was recommended to me by a professional sprayer, but ultimately, an air brush job would get you a supremely good result, though I'm not sure about putting acid etch through an air brush?
After 24hrs I apply the top coat (three or four light coats, but I spray to a 'wet' coat for best results).
For this I use VHT high temp black enamel, satin finish engine paint from Frost auto restorations, which has to be baked for best results, but I have elected to let it harden over time; it has proved to be quite tough even after a week or so (fewer coats on the script, for better paint clearance). It dries quite quickly, and I wait 15 minutes between coats.
Once dry (I allow around 3 hours before etching the script, but I cant tell you if this is best or not; it is always a concern that if the paint is too hard, it will chip outside of the groove?My worries may be unfounded, however (I'm relatively new to this)? I would suggest practicing on a spare sideplate to get the best time frame; sadly I have not yet done this.
I can tell you that clearing out the script paint too early, will make it stick to the scribe and create gooey mess....not good!
So...this is where the anxiety starts to grip you as you lower the scribe to the script for the last time, and if you have shakey hands like me, it is a real problem!
I mount the side plate on a wooden block with holes for the gear pillars and AR dog pillar, and use a bit of packing to lift it slightly from the block.
I use the same wooden block and an inspection lamp for etching out the paint from the script. In theory, the lack of etch primer in the groove, should allow the paint to lift out nicely. Don't rush this! And if the scribe stops, don't be tempted to push a little harder; come in from the other side of the blockage. It is so easy to mess this up in the final straight.
Assuming all went well, wait a few days and polish lightly with Carnuba wax, which is kinder than T-cut, but still very effective; try not to cut through to the primer (a few wipes and inspect)..
That's about it really, a very amature perspective, of which I am very open to criticism and schooling (anything to help to achieve a great result).
To add: in my photos you will see the cotton bud ends sticking up from the reel body; These are screwed in to the holes, and continue through the foam and are taped off at the back where they emerge. I now cut these cotton ends off, as they get in the way, and can cause problems.
Some pics show the sideplates before paint clearing, but I always clear the script after each process.