Pinballs

Finally, the playfield of the Whoopee has been completely restored. Pictures of the complete process can be found here:

I've done the following:

• Thorough cleanup, using meths and Red Devil
• Sandpapering, 400 to 240 grit
• Levelling of playfield inserts and refill of all scratches and chips:
  
  
• Paint touchup using acrylic paint (primary colors and my own mixes)
  
  
• Repainted insert black circles
  
  
• Vitrification using transparent glossy product, 3 coatings
  
  
• Lustring with orbital smoother
  
  
• Cleanup of all plastics using washing-up liquid
• Changed all rubbers
• Cleaned all switches and stepper units using 240 grit sandpaper
• Cleaned all balls and metal parts using HCl acid

Note about cleaning metal with acid: the balls were completely rusted. See this picture for reference:

After using acid, they turned out like this:

Worry not. Polish them gently and they'll turn very nice, see as the process goes on:

Here's my little vitrification HOWTO:

For starters, the playfield must be stripped naked of all parts and perfectly clean, without residual detergent. I recommend "rinsing" using water and/or glass cleaner (which is very volatile and leaves no trace). Once the playfield is ready:

1. Sandpaper it (grit 400 to 240)
2. Remove dust residuals using glass cleaner
3. Cover the playfield while it dries out, to avoid new dust
4. Prepare the vitrification product. I used a monocomponent Transparent Glossy product (brand "Syntilor"): it must be gently moved up & down to blend the product. I say gently because if you shake it too harshly, tiny bubbles will form which will be very difficult to get rid of
5. Apply the product using a lacquer roll. It makes it very easy to apply the product uniformly across the whole playfield
6. Let it dry for 6h, protecting the playfield against dust (any speck of dust at this point will be forever trapped in the vitrification)
7. Sandpaper, 400 grit
8. Repeat the above 3 steps 2 times (total: 3 coatings)
9. Depending on the desired effect, you will either not sandpaper the final coating (for glossy finish), or sand it very gently with an orbital smoother at 400+ grit for satin-finish
10. Finally, polish the playfield using P5 polish paste. BEWARE: do not wait more than 24h between the final coating and polishing. After about a day, the vitrification is so hard it's impossible to polish

Note: during the whole process, the playfield must be perfectly horizontal (use a spirit level).

Here's the final result: