Topspin against backspin.

If you could post a short video of yourself looping against pushes and chops I'm pretty sure  you'd get some help.  Without seeing your stroke, timing, blade angle, and stroke plane it is impossible to give precise suggestions.  Do you have access to a coach?

Assuming you don't have a coach handy, it might be best to work on this against medium or even medium light pushes - at least until you get the timing down and get more relaxed and comfortable with the stroke.  ANY tension (too much grip pressure, tight hand, wrist, forearm, elbow...) tends to really drop blade speed, which is a killer. 

As mentioned before, timing is critical.  Your backswing should immediately (or darn near immediately) flow into your stroke.  Don't drop your blade too early!  Your backswing is like winding a spring - but a spring that only stays wound for an instant.  If you stop at the bottom of your backswing too long, this "spring effect" tends to disappear.  Bend your "playing hand" knee as you rotate your shoulders back and down, then push off with it when you swing forward and up.  Your off arm should move with your playing arm!  Imagine they are tied together with a string.  Use the off shoulder and arm to pull up and around.  This gets your shoulders and core involved.  Feel free to add a little "elbow" through contact. Finish the stroke high.  Even "really high" is ok - whatever helps you get the feel.

Watch any top player playing a chopper (plenty on youtube or ITTF-TV).  Ignore their "Kill" loops for now, but pay close attention to their normal and control loops.  See how relaxed they are.  Watch their timing.  Watch their stroke angle.  Watch their blade angle.  Watch their movement and positioning.  Watch their finish position.  Watch several players and see if you can find one with a similar body type/playing style as you - or kind of close.  It isn't essential, but some players are longer and slower (e.g. Samsonov) and others are quicker (FZD or ML) Next, get in front of a large mirror and duplicate what they did.  Do it very slowly.  VERY SLOWLY.  Get every detail perfect - ready position, foot position, posture, backswing, blade angle(throughout), stroke plane, (imaginary) contact, finish, return to ready position.  Do this many, many times - yes, your family/friends, and pets will think you are crazy - it will really help.  This "shadow training" will help teach yourself how to put it all together.  Doing it slowly - even painfully slowly - works fine.  Your brain needs to learn the sequence and positions - these are the same at any speed.  After doing this carefully for several hours (over a couple days) you can gradually speed up the shadow strokes - but be careful to keep everything in the correct sequence and hit all the correct positions.  I recommend doing this a bunch before trying to play. This will help you get your technique down without stress or confusion - or fear of failure.  Sleep on it at least twice - your brain can do magic overnight!

I recommend not opening your blade too much.  "Open blade" strokes can help get the ball over the net, but yield a less spinny ball that is pretty easy to attack.  This type stroke is finet as a deceptive "dead loop", but it is normally only effective when mixed in with normal, spinny loops.  I do not, however, think it a good learning tool for a proper spinny loop.  Also, while I'm sure there are some who really have this shot down, most (admittedly these lower level - guys and gals struggling to learn to loop) that I see using the open blade technique are fairly erratic - tiny blade angel changes seem to have big effects on the trajectory.

Good Luck!

bes

I suspect what I was actually doing last time wasn't so much looping it back but simply pushing it (with racket at 90 or slightly open) back really fast. That player in particular has much stronger backspin, and I had no luck at the time looping it back except for a few lucky shots. I will try the technique I found the other day next time...   But I had zero luck with simply using my knees and a vertical stroke. In this case, my rubber might simply be too fast for me, and too susceptible to spin.

No, I'm not going to record my practice and put it online. It would be too embarrassing. 

Yes, I have coaches but one of them only speaks Chinese... lol.

For what it's worth, I don't have much of a problem using the vertical stroke technique to return backspin shots in multiball practice. It's only against a full-on chop that I have problems.

And what does hardbat technique have to do with modern table tennis? Are not hardbats more or less spin-free (or at least not susceptible to spin).

There are a pretty good number of folks at my club that too often use their rubber as a crutch.  Rather than getting into position and actually stoking the ball, they often reach out and bump it, wrist it, or do several other things I don't have names for.  Often these lazy half-hearted strokes "sort of" work thanks to their rubber, but they still aren't generally effective or consistent. 

Putting a hardbat in their hands is the quickest way I know to illustrate (to them) that they are not actually stroking the ball.  After they see that the ball just drops or bounces short of the net when they are too passive or simply stroke across the ball, they usually realize they need to actually stroke forward if they want to hit the far side of the table.  Even a short session with a hardbat can really help their stroke.  As a bonus, their footwork usually also improves since it is easier to stroke the ball when you are in a "decent" position.

For the record, this experience has damaged none of their inverted games - every one of them was soon hitting better - often much better - shots with their inverted.  I'm certainly not promoting hardbat as a cure all, but the fact that it isn't inverted doesn't make is useless - even for inverted players.

bes

Practicing in front of the mirror is better than using a hardbat.  Hard bats have their benefits but note that the racket angles are different.

The real feedback should come from a higher level player/coach watching or analyzing your stroke, which is why people who are not willing to post at least some of their practice online, even if temporarily, are not going to get any fixes if they don't have someone coaching them in person.  IT's too easy to lock in and shadow practice bad habits in this sport because the mind likes to deceive itself.  We all look like Ma Long in our heads, but the camera always tells the truth.  Moreover, the camera's truth is only visible to those who can see what it is really saying.

Spin quality is only one of many important things - optimal technique has things like stroke consistency or making the body parts function properly together built into it as well, and you aren't going to tell that by looking at the spin on the ball.  That said, the spin on the ball reveals timing, and that should always stay with you or improve even when your technique changes.

Also, modern table tennis includes a wide variety of surfaces including short pips with no sponge.  Depending on the equipment that you are using, hardbat techniques can be directly or indirectly relevant.

Oh, OK. For some reason I was thinking hardbat was just with the wood...

baribari, I see you aren't a fan of 1080p smart phone cameras that be attached to a tripod these days and replayed back instantly in HD. Fair enough. Maybe I'm wrong and my advice is misinformed.

In relation to the YoutTube video of Austalian player William Henzell, I know a guy that coached him for quite a few years and still helps him with his game etc. I could ask him about this "vertical stroke" if you like?

By typical I meant shot off-hand. I know it could be useful in most cases (judging overall form), but I think in this case you would need high-speed video (much slower than smartphone slo-mo). The difference between going into the net and getting onto the table is pretty slim when you're looping a hard chop.

I would welcome any details on the strokes of high-level players, of course!

This works even better when hitting vs glass or wood (2nd best) rather than the wall - I have a big closet with a big glass door (thick glass - no damage) and position the table there - the amount of underspin on the 2nd ball is really incredible - it also works hitting against a wooden door preferably not solid. Yet no matter how monstrous the backspin is I swing up AND forward, and maintain a 75 degree angle - of course a lot of racket speed and power - this is the only way to produce a quality dangerous shot - if the aim is just to get the ball back on the table it's a different thing - but in that case pushing back makes more sense. 

Thanks so much for smileys pgpg. It certainly appears that I need them as I resorted to posting humor that was solely for my own entertainment. 

As baribari likes William's play off backspin, I'll ask William to post some tips here.