PVC pellets. Photo: Rick Schmidt / Home Theater Hifi
Now that we have the stamper, we’re ready to start making records. The next part of the process is basically a giant waffle iron. Stampers for each side of the record are attached to a 100-ton hydraulic press. Pellets of PVC plastic - vinyl - are melted down into lumps that are around 3 times the desired thickness of the record. These vinyl lumps are called biscuits. The vinyl paper labels are placed on the top and bottom of the biscuit, and this label-biscuit sandwich is inserted into the hydraulic press. Steam from the hydraulic press heats and softens the biscuits just before the jaws of the press slam down. This imprints the ridges from the stamper into the biscuit, creating playable grooves with the audio information of the original lacquer and baking the paper labels into the center of the vinyl, no glue required. The imprinted vinyl is hardened in a cool water bath, excess material is cut from the edges, and and what has finally become a vinyl record is inspected for quality. If it does not meet quality control standards, the material is (sometimes) melted back into biscuits and sent back into the press.
Biscuit about to be pressed. Photo: RIP-V
Usually pressing plants produce a run of four or five records before the full order is produced. These test pressings are sent to the record label and artist for final approval on sound quality. If they hear something wrong, such as an egregious pop or other distortion, the plant might have to start the whole process from the beginning. Color vinyl can be made by using different colors of PVC pellets to create the biscuits. Biscuits can be hand-mixed to make various patterns, including splatter, color-in-color, A-side/B-side, and more. Vinyl Moon uses the splatter effect on many of our own releases - you can see how that’s done in the video below.
WHAT SOUNDS BETTER, BLACK OR COLOR VINYL?
This is a testy issue, but the bottom line is: the jury’s still out. Untreated PVC is a translucent color before a “carbon black” pigmenting compound is added, giving traditional vinyl the rich black color we associate with it. This “carbon black” acts as a homogenizing agent, which smooths the vinyl and reduces surface noise. Therefore, one argument is that black vinyl should be less noisy than colored vinyl as it has the most surface-noise-reducing compound present, with clear vinyl supposedly being the worst and opaque colored vinyl being better (as it contains more homogenizing agent than clear vinyl, but less than pure black).
Other critics and pressing plants claim the opposite, that translucent colors generally have less surface noise than opaque colors - Gotta Groove Records in Cleveland, for instance, has a handy guide of their quietest-to-noisiest vinyl colors HERE.
However, another argument says that ordering colored vinyl also means you are getting virgin PVC pellets, as opposed to recycled biscuits from a previous order at the pressing plant. Virgin vinyl can help the quality of a record as it often contains less dust and other imperfections that can be added when the material is heated and cooled multiple times.
HOWEVER however, others contend it can take molds, extruder lathes, and other pressing plant machinery a while to become totally optimized for each album pressing. Because orders for colored vinyl tend to be in smaller quantities, the equipment has less of a chance to be evenly heated and precisely timed. Though this might make a case for buying mass-produced records over small runs, rather than settling the black versus colored vinyl debate.
The reason this issue is almost impossible to settle is that thousands of little factors influence the quality of each individual record in the same pressing, let alone from album to album. From the differing characteristics in the original audio master, to effects of the location and machinery at a particular pressing plant on manufacturing precision, to the condition of the vinyl used, there's no way to say definitively that Method A is better than Method B in every single instance. And maybe that's part of why we love vinyl so much.
This author’s opinion is that the uncontrollable variables, the little pops and clicks that vary from record to record, are a crucial and unavoidable part of the vinyl experience. It means that every record - and, in many ways, every playback - is a singular experience. If you think (like I do) that colored and patterned vinyl looks great, that should be more important than chasing an unattainable level of perfection. Thanks to technological advances, you can get uncompressed & lossless digital audio files with surgical precision and clarity that will sound identical when passed from computer to computer. With vinyl, the musical experience is unique to you and that moment.
Sources: http://www.misfitscentral.com/appendices/appendix.php https://en.wikipedia.org/wiki/Direct_metal_mastering https://en.wikipedia.org/wiki/Production_of_gramophone_records http://electronics.howstuffworks.com/record-player3.htm http://gizmodo.com/5987010/how-records-are-made https://en.wikipedia.org/wiki/Electroforming http://www.discwizards.com/Vinyl/Audio-Mastering-and-Mixing-Tips--for-Vinyl-Lacquer-Cutting-and-Pressing.htm http://www.soundonsound.com/sound-advice/q-how-does-mastering-differ-vinyl-and-digital-releases http://www.themasterdiskrecord.com/2013/03/scott-hull-on-vinyl-part-five/