Using a feather edge on cement render what am I doing wrong?

[RBN]

I thought this would have been asked before but haven't found anything in the seach.

I've been plastering for around a decade and recently decided to have a go at rendering my garage.

I battened off the large wall into smaller managable sections, followed the tips on here for preparing the substrate and getting the mix right and found it went on well (thanks everyone). I can get the wall looking pretty decent with just my trowel, but obviouly still need to remove the odd high spot and fill in the low spots.

BUT when I come to level off with the feather edge it all goes a bit wrong.

Either I push lightly and almost nothing comes off the wall, or (more often) with a firmer push the render sticks like glue to my feather edge and I pull big chunks of it off the wall. I have now tried this multiple times and keep getitng the same bad result.

When am I supposed to apply the feather edge? (how soft should the render be? completely fresh and wet? slightly firm to touch? etc)

How hard am i supposed to push it against the wall?

How flat and/or smooth should I be trying to get the wall with my trowel before using the feather edge to flatten. As a seasoned plasterer I naturally try to get it as flat as possible with the trowel.

How flat am I trying to get it with the feather edge? Perfectly flat or just a bit better than a trowel finish? If the latter how much of a dip/bump can I leave in mm?


regards RBN

 

[23vc]

It should be wet when you rule it, the more it dries out the harder it’ll be to rule off.
Are you ruling against a bead, or one of your battens? If so it should rule off a treat
Bit harder if you’re doing it freehand
Only thing I can think of from your description is it’s firmed up too much? With a standard chamfered featheredge you can use either side , square side to ‘cut it off’, chamfered side to ‘rule it in’ or flatten it
Ruling off will always take a few goes, with a bit of filling in between, it’s the hardest part imho, but you need to aim for it looking pretty decent with very few hollows, if you’ve want it to float up nicely and end up looking decent

 

[roy c]

Are you putting on a "scratch coat" first?

 

[stevethespreader]

When am I supposed to apply the feather edge? (how soft should the render be? completely fresh and wet? slightly firm to touch? etc)

How hard am i supposed to push it against the wall?

How flat and/or smooth should I be trying to get the wall with my trowel before using the feather edge to flatten. As a seasoned plasterer I naturally try to get it as flat as possible with the trowel.

How flat am I trying to get it with the feather edge? Perfectly flat or just a bit better than a trowel finish? If the latter how much of a dip/bump can I leave in mm?


regards RBN

if your a seasoned plasterer have you ever used a feather edge on floating indoors? As a rule of thumb lay on the render the width of your feather edge then rule it off and then carry on laying on you should not be messing around with the trowel trying to get a finish before its ruled off this will ruin the render by bringing the water to the surface but like 23vc says if you have sectioned it off and ruling off from beads it should be easy , and as roy asks are you using a scratch coat? Also are you using a plasticiser?

 

[23vc]

As a rule of thumb lay on the render the width of your feather edge then rule it off and then carry on laying on

Never heard that before but that sounds like a good plan to be fair, I’ll try that next time i do some.
Even tho my feather edge is 3 foot lol

 

[stevethespreader]

Never heard that before but that sounds like a good plan to be fair, I’ll try that next time i do some.
Even tho my feather edge is 3 foot lol

Well that's how I was taught , using say a 2m or so feather edge obviously you have conditions affecting how much you can lay on such as suction but generally lay on 6ft or so the length of your straight edge then check to see how it's firming up and act accordingly lol I suggest you get a longer edge their as cheap as chips in wickes , I used to have a 3ft one cut down from a 6ft from wickes me and another spread went half's lol I left that on a job in Bournemouth I was gutted so bought a small refina edge to replace it , don't take my word for it though there's a couple on here with much more render under their belt than me I'm sure they will tell you how they do it

 

[RBN]

Thanks for all the replies. I've not been able to reply until now due to problems with my pc.

It should be wet when you rule it, the more it dries out the harder it’ll be to rule off.
Are you ruling against a bead, or one of your battens? If so it should rule off a treat
Bit harder if you’re doing it freehand
Only thing I can think of from your description is it’s firmed up too much? With a standard chamfered featheredge you can use either side , square side to ‘cut it off’, chamfered side to ‘rule it in’ or flatten it
Ruling off will always take a few goes, with a bit of filling in between, it’s the hardest part imho, but you need to aim for it looking pretty decent with very few hollows, if you’ve want it to float up nicely and end up looking decent

if your a seasoned plasterer have you ever used a feather edge on floating indoors? As a rule of thumb lay on the render the width of your feather edge then rule it off and then carry on laying on you should not be messing around with the trowel trying to get a finish before its ruled off this will ruin the render by bringing the water to the surface but like 23vc says if you have sectioned it off and ruling off from beads it should be easy , and as roy asks are you using a scratch coat? Also are you using a plasticiser?

It certainly sounds like I am spending too long and trying to get too good of a finish with my trowel. Even when going between the battens I tried to get it as flat as I could with my trowel first assuming that the feather edge was simply to finish it off after getting it pretty much flat.

It does seem like it starts sticking to my tools (and coming off the wall) only after I have been working it for a while. No i have never used a feather edge before for any of my previous work.

Yes I am using a plasticiser at the amount recommended on the bottle (I think it said apply 150 to 300ml per 50kg of mix and I'm running around 250ish)

Are you putting on a "scratch coat" first?

Yes I applied a scratch coat. And applied the top coat 2 days later having wet the scratch coat first.


SO to clarify I should be aiming to apply the render quickly, not spending much time on trowelling. Then go in with the feather edge (i'll practice using the different sides). If it's wet/unworked enough it should adhere better to the wall and allow me to take some off/apply more.

Does that sound about right?

 

[23vc]

Yes. Just get it on and rule it off, no troweling.

 

[stevethespreader]

rbn A float is a must for render so get a float by rubbing up with a float you are opening the grain up a trowel will leave it with a closed finish

 

[John D v2.0]

using a plasticiser at the amount recommended on the bottle (I think it said apply 150 to 300ml per 50kg of mix

That sounds like a lot!
I'm no way am expert but just make sure that's right, check it doesn't say per kg of cement rather than of the finished mix.

 

[RBN]

JUST WANTED TO SAY THANKS! Following the advice given here went on to finish the garage and for a first attempt it looks great.

Keeping the trowelling to a minimum and using the feather edge promptly after apllying the render was the key. And something which would have taken me a lifetime to figure out on my own.

Happy days.

 

[stevethespreader]

JUST WANTED TO SAY THANKS! Following the advice given here went on to finish the garage and for a first attempt it looks great.

Keeping the trowelling to a minimum and using the feather edge promptly after apllying the render was the key. And something which would have taken me a lifetime to figure out on my own.

Happy days.

Did you use a float?