Does anyone here have the Rossa PG? How do you like it? The Rossa PG seems to be nice from what Portaspresso shows on their website, but I have some concerns about the aluminium rather than bronze construction (aluminium typically cools down way too fast when exposed to air) and the fact that the pumped air seems to become in direct contact with the brew water (how clean is the air coming out of a bicycle pump?). The Rossa HC is very nice, but with the PG I guess it is easier to focus on getting the desired pressure profile... Any thoughts?

I have the Rossa PG Air and I am very pleased! There is plenty of mass in the unit so it holds temperature very well. I do two warm up fills and a third for extraction.

You want to use a decent pump in good condition. The air from my Lezyne Alloy Floor Drive Pump doesn't add any smell to the air. It takes 4 pumps to charge the air cylinder to over 9 bar, about 140 PSI and this allows a 6 bar extraction. I have a shock pump for travel and that takes quite a few more pumps to reach 9 bar.

I'm really having a great time experimenting with different pressure profiles. A whole new world of flavor at lower pressure. I have so much more control over the process than I do with my Rocket Giotto Evoluzione V2, especially water temperature and pressure. I control the initial charge of the air cylinder and the valve provides very precise control over the release of that pressure. I can ramp the pressure up as slow or fast as I desire and hold the pressure at any point I choose.

Cleanup is extremely simple. The puck knocks out dry. Wipe out the basket and dry everything off. Done. No back flushing, no removing and wiping down the shower screen and no descaling.

I'm also extremely pleased with the Rosco Mini hand grinder. My Rocket Mazzer Mini Type B has been unplugged since the Rosco arrived and the Giotto is only used for frothing milk these days.

Thanks bridaw. Have you checked by any chance with a milk thermometer the rate at which the water temperature is going down once the machine is warmed up? For the HC I have read that the temperature was going down from 96C to 91C after a minute, which is pretty good.

Also, is the aluminium anodized or naked?

Thanks!

The aluminum is bare. I use a milk thermometer to make sure I don't overshoot my desired extraction temperature. I have been experimenting with lower temperature and pressure since I couldn't do that easily with the Rocket. I have watched the milk thermometer for 10-15 seconds and was satisfied the unit holds temperature well. After you preheat it only takes a few moments to screw on the filter basket, carefully invert and start the extraction.

I saw your post so I boiled some water and preheated the Rossa PG Air to 200F and hit my timer. I really should have used the probe on my Fluke FoodPro Plus but this isn't a very scientific test. The temperature was 193F after one minute, about 186F after two minutes and 180F after three minutes. It is about 75F in my kitchen.

Thanks. So heat retention is good then. I guess one could always insulate the device a bit to improve things further. About the aluminium, it must tarnish quite a bit over time if it is not anodized?

I'm happy with the heat retention but I've been experimenting with pre-shot temps in the lower 190s (F). Most of the time I consume the shot immediately after extraction so 200F is way too hot. I can dial in tasty shots on my Rocket but I'm loving these extractions at lower temp and pressure so much more. You can preheat the device hotter than the final extraction water temperature if you choose.

You could always purchase the Rossa TR Air with the optional Pressure Adapter. That would add quite a bit more mass and I considered going that route. I had a pleasant email conversation with Ross about my dilemma and ultimately decided on the Rossa PG. I'm very pleased with my decision.

The device isn't heating the water so I'm not really concerned about the 50 or so seconds of contact with the extraction water. So far tarnish hasn't been a problem but my understanding of tarnish is a nice patina is a good thing. A thin surface layer of aluminium oxide formed from exposure to air prevents further oxidation. In this application I'd prefer that natural process over anodizing any day.

That said, it stays very clean inside the device because the basket is the only thing contacting coffee. I give it a quick (optional) rinse under hot water and dry with a towel that wasn't washed with fabric softener or dried with static sheets. It dries quickly because it retains so much heat.

Thanks, this is a good idea about buying the TR + a brass pressure adapter. Another option I guess would be to buy the HC, and if I don't like the screw system, remove the piston and have an adapter machined to fit the air tank from the PG.

Edit: I tried looking for toxicity information for both aluminium and brass, and from what I have found, it seems that aluminium is not worse than brass. Stainless steel would be better from a toxicity point of view, but it does not have a very good thermal conductivity, so it would be difficult to warm up. Does my reasoning make sense or not?

kreyszig wrote:Thanks, this is a good idea about buying the TR + a brass pressure adapter. Another option I guess would be to buy the HC, and if I don't like the screw system, remove the piston and have an adapter machined to fit the air tank from the PG.

Edit: I tried looking for toxicity information for both aluminium and brass, and from what I have found, it seems that aluminium is not worse than brass. Stainless steel would be better from a toxicity point of view, but it does not have a very good thermal conductivity, so it would be difficult to warm up. Does my reasoning make sense or not?

I searched about corrosion before making the purchase. My experience with hard anodized cookware is the layer eventually wears, flakes and microscopic fissures in the coating can lead to corrosion. Stainless of course simply stains less and isn't stain proof. I believe aluminum is more corrosion resistant than stainless, weighs half as much and is less expensive.

The quoted bit below is found at this link. There is a lot more information out there.

Aluminum is actually a very active metal, meaning that its nature is to oxidize very quickly. While a weakness for most metals, this quality is actually the key to its ability to resist corrosion. When oxygen is present (in the air, soil, or water), aluminum instantly reacts to form aluminum oxide. This aluminum oxide layer is chemically bound to the surface, and it seals the core aluminum from any further reaction. This
is quite different from oxidation (corrosion) in steel, where rust puffs up and flakes off, constantly exposing new metal to corrosion. Aluminum's oxide film is tenacious, hard, and instantly self-renewing.

If you still are not comfortable with the bare aluminum, contact Ross at Portaspresso. Perhaps if there is enough demand he would make a Rossa PG Air from the same materials as the HC.

bridaw wrote:I searched about corrosion before making the purchase. My experience with hard anodized cookware is the layer eventually wears, flakes and microscopic fissures in the coating can lead to corrosion.

Fair enough

bridaw wrote:Stainless of course simply stains less and isn't stain proof. I believe aluminum is more corrosion resistant than stainless, weighs half as much and is less expensive.

Well there are all kinds of "stainless" steels. 304 has a very good corrosion resistance. Stainless has a poor thermal conductivity as I mentionned though, so it is probably not the best material for this unpowered application.

bridaw wrote:If you still are not comfortable with the bare aluminum, contact Ross at Portaspresso. Perhaps if there is enough demand he would make a Rossa PG Air from the same materials as the HC.

Thanks. I sent him an email today about my dilemma. I will see what he replies. It would be great if he could make a brass PG!

On a related but slightly different topic, do you think Ross' statement that the Rossa devices can match or exceed the results from any machine with a seemingly good consistency is reasonable? His arguments are compeling and since I saw that the temperature can be well controlled with these devices, I currently don't see how it could not match the results obtained with the best commercial lever machines, particularly when using the PG or the TR + pressure adapter

kreyszig wrote:Thanks. I sent him an email today about my dilemma. I will see what he replies. It would be great if he could make a brass PG!

On a related but slightly different topic, do you think Ross' statement that the Rossa devices can match or exceed the results from any machine with a seemingly good consistency is reasonable? His arguments are compeling and since I saw that the temperature can be well controlled with these devices, I currently don't see how it could not match the results obtained with the best commercial lever machines, particularly when using the PG or the TR + pressure adapter

A brass PG would be nice. It would be really heavy. I was surprised at the satisfying heft of the Rosco Mini.

There are a few threads that discuss the portapresso system and people focus on cost and fail to realize this is an excellent espresso making system allowing precise control that happens to be portable. Of course you must provide your own hot water.

Yes, I believe the Rossa/Rosco can equal and exceed the results of systems 3x the cost.

Long-winded answer: Back in early November I spent $3100 on a commercial grinder and a plumbable rotary pump semi-auto HX machine. I began roasting single origin beans every week so I started single dosing the grinder. Thanks to everything I've learned while lurking here, I've been drinking the best espresso I've ever had in my life and it keeps getting better as I improve in consistency on the roasting side. I'm no expert but I know what tastes good to me and I was making great stuff on the Rocket/Mazzer setup before the portapresso "travel" system showed up. The Mazzer has been unplugged for weeks and the Rocket occasionally froths milk once a day. I'm a solo coffee drinker that makes 1-2, sometimes 3 double shots a day so the Portapresso system is all I use now.

I can't really say I wish I could do it all over again and save a bunch of money because it was my journey with the Rocket that led me to the Rossa/Rosco. I never would have spent the money on this setup until I got proficient on the Rocket and realized the Rossa offers more control in a portable system. Once it showed up and I tasted the results, it is all I want to use. It is interesting how much different the same bean, same roast, same grind can taste with a different pressure profile or temperature. In such a short time I went from newbie to cutting edge. The "9 bar is optimum" crowd doesn't know what they are missing. As more people experiment with pressure profiling maybe some day semi-auto machines will offer precise temperature and real-time pressure control with USB ports for user programmed varying pressure profiles.