I like the luxurious feel of a heavy razor. Whether or not it shaves better I'm not sure.
I also like a razor around the 100g mark. I've developed a slight tremor in my right hand due to nerve damage from a workplace accident, so a slightly heavier razor keeps the shakiness down.The sweet spot for me is around 100g. Stainless steel seems to have an ideal density for razors. It creates a perfect razor size at this weight.
I used to be in the "heavier is better" camp, until I happened across a Wardonia razor made almost completely of urea plastic.
Totally agree with the sweet spot over time discovery... All the math and science aside it really takes time to find what weight works best for each individual. My sweet spot is somewhere between 70 - 100 grams, but my Standard Razor is perenially one of my best preformers and is only about 50 grams. The first time I really noticed a weight sweet spot was a few years back with a Parker Variant and an Ikon SBS w/ Bulldog handle about the same time. I found both uncomfortably heavy and have since paid closer attention to total weight when purchasing new razors... With a three piece razor you can change handles to easily customize the weight and balance but with adjustables you get what you get in most cases, so either you like it or move on.+1 for Ad Astra: You find a sweet spot with weight, over time, and everything else is too light or too heavy. I started the DE journey with a Merkur HD and hated it! Only after getting a Merkur Progress did I realize that I needed a more aggressive razor with more weight. Currently, a Parker Variant provides the best 2-pass shave (WTG and XTG). I intuitively tilt my head to the side on an XTG pass so that the weight of the razor is effective. When doing a 3 pass shave, the Variant is too heavy for a comfortable ATG pass, but the Merkur Progress, a slightly lighter razor, provides a comfortable ATG pass. I just cannot use light razors. Even a Fatboy is too light to provide a close 3 pass shave. YMMV...
Comrade Dyatlov approvesMy preference is 70-75 grams. Not too light, not too heavy
It all comes down to slight of hand. I have arthritic hands it isn’t the weight, you can control that easily. It’s the grip with arthritic hands, the smaller and lighter the item the harder it is to grip. All my brushes are large knot, easier and more comfortable to grip and hold. I prefer light razor heads and heavier short handles 14mm is better then 13mm In diameter. When I used a plastic slant it was difficult to use, it wasn’t the weight but the lack of weight which was uncomfortable. There was no balance it was too light and more difficult for my hands. Too light is worse then too heavy. Balance is choking up or down on the handle.An interesting question. It does seem to me that mass or weight (or the combination thereof) increases the aggressiveness and the effectiveness of a safety razor.
The downside is mass and weight can be counterproductive if the shaver has a painful arthritic hand.
I also agree with the points in the original question: that weight is good on a downstroke, irrelevant on a sideways stroke, and counterproductive on an upstroke.
I'd like to hear more discussion of this question, especially from any physicists on the forum.
Comrade Dyatlov approves
I had to google Comrade Dyatlov