Repairing hairline cracks in plaster
Hi folks,
I received a call recently for some friends, looking for help with their plaster. They live in an old home (built in the 30’s), and vibrations from the road reconstruction in front of their house this last summer left their front two rooms with a series of hairline cracks, most running from the corners of door and window headers up to the ceiling, and some others running more or less parallel with the lathe. Insurance will cover the repair. The insurance estimator came out, and provided them with a written estimate that specified that a plasterer out to recover the affected walls with a skim coat of plaster.
Is the insurance estimator suggesting the best way to address this issue? The cracks are all hariline, with no chipping, breakout, etc. The walls are textured, so I can see how simply affixing a new plaster veneer over the entirety of the wall might be cheaper and faster than filling with patching compound, sanding, and painting.
I’d be very interested to hear from anyone with experience along these lines, especially plasterers.
Thanks for your time and help,
Michael
michael.j.m.carlson@gmail.com
Replies
Old Plaster Master taught me this .
You need a misting bottle, a couple of old toothbrushes, plaster mix, and either rags or a sponge and bucket.
Mist the crack , use a toothbrush to clean it out well. If you have air, gently blow the crack out.
Mix up a stiff plaster batch (not much at a time) re-mist the crack ( if you used air), use the toothbrush to brush and force the plaster into the crack, filling the crack to the surrounding surface or just proud of it. .
Wait until the plaster is nearly set and use the rags or sponge to GENTLY wipe the area around the cracks clean , being careful not to gouge out the filled crack.
Let it dry well and paint it
The OP was asking about hairline cracks. What's the width range you've used this technique on?
-- J.S.
From hairline ( the kind of crack that seems to just taper off into the field of the plaster wall) up about 1/4 " after cleaning out the loose debris.
I am not a plasterer or drywaller by trade, This is just a trick a very fine older plasterer taught me on a job some yrs. ago. I have used it more than once and always had success with it.
Lacking plaster at hand I have also used floor patch material (The stuff the vinyl/lino./ marmoleum installers use) to achieve the same results. Have to be careful with that though, the chemicals in it bleed though paint and leave it "burned " Like painting over "hot mud", so it requires a good coat of something like kilz before any other painting.
sharpen the V cutter / punch on an old style can opener into a gouge and open the hairline craks a bit befor using dovetail's method...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
That is a good point, I agree.
works like a champ...
good for removing loose material too...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Priceless information Dovetail, many thanks to ya!
blue
whats the best way you know, to make old plaster look like a new house?
Find a good local plasterer.
Seriously , I am not a plasterer, while I have repaired some during my career I wouldn't know what to tell you with any assurance that my advice is of merit.
Might try starting a new thread asking specifically what it is you want advice on and see what you can troll up from the pro's here.
for hairline cracks use drywallmud or hotmud and repaint; your going to get new cracks anyway. If you want no more cracks ever , your going to have to start from basics. Either demo down to the studs, check for any weaknesses, put new blue board and replaster. Or if your feeling lucky put netting [chicken wire] over old plaster and then your standard two or three coats. I prefer the patch and paint method because I'm lazy and don't have much money. have fun.
DW mud is too dissimilar...
patches don't seem to stay...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Agreed. My old time plasterer recommends a plaster product called EasySand 90 for beginners. He also recommends digging out cracks to about 2" wide to be sure that the stresses are all released, and the remaining sections of plaster aren't putting any loads on each other. Also, to undercut the edges of the old plaster so the new goes behind it and is held like a dovetail.
Cracking problems fall into two basic categories: Normal settling and shinkage, or deep structural/foundation trouble. If cracks keep coming back, you have to look at the big picture and be prepared for bad news.
-- J.S.
That'd be a half dovetail...
2' is a bit excessive isn't it...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Edited 12/5/2006 1:26 pm by IMERC
I thought so, too. The only place it would help to go wide is if the adjacent pieces have shifted out of plane with each other. Wider makes that easier to hide.
-- J.S.
I'm partial to 30 min mud and float the cracks out 4 or 5"
also any thing wider than about 1/4" is a multi-step process...
1st step.. fill but leave the fill a bit shallow... 20 min is good mud for this.. really wide cracks... add CC sand to the mix... use ice cold water to mix with to delay the fire off time..
2nd step.. trowel or knief flat..
3rd step.. float and blend in the repair..
cracks smaller than 1/4" step 2 and 3..
tried D-mix once... won't do that again...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
"tried D-mix once... won't do that again..."
Me either!! Either the real thing (I use Imperial plaster) some hot muds, or as I said earlier, floor patch. Of everything I have used real plaster leaves me with the smoothest finish when done.
I don't open the cracks any more than needed to clean them out, I learned from mistakes that I could cause more damage by scraping too much in an attempt to clean up a small crack.
And yes, some cracks have reappeared over time, this is a patch , it doesn't address whatever underlying causes there are. Making sure the dust is removed from the crack and ensuring that you dampen the crack, not just the surface, but the sides and bottom ) seem to be keys to the success.
If cracks reappear because things are still moving, perhaps a flexible material like caulk would work better. In that case, scraping it out to maybe 10 -20 times the amount of anticipated movement would minimize the percentage of compression or elongation the material would need to handle.
-- J.S.
how would you get the caulk to look like the original smooth finish..
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
That's probably a challenge for the manufacturers, to come up with a material that will dry without shrinkage or expansion, retaining the surface made by the putty knife. Of course it would change a little as the building moves, but if the change is like 5% or less, it might not show as much as a crack would.
-- J.S.
I can't invision the asthetics flying with using caulk...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Interesting thread...I was just in the local hardware store, saw any number of new (to me, anyway) premixed Dap patching compounds....one was "elastic", & the list of ingredients included some hydrocarbons....Someday maybe I'll try them ;-)Most of the hairline cracks I come across are on walls that have at least two coats of flat latex on then, so I don't worry about getting a slick plaster finish and use standard hot mud to tape...and use paper tape...if there is enough movement going on for the crack to re-appear, it won't show through the paper, since there generally isn't enough stress to rip the embedded tape...and then finish with regular mud...as long as you get the base clean, and let everything cure well, it works for me
has any of this been helpful..
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
You tried D Mix and didn't like it?!!!!!
Please tell us more?
blue
shrunk..
bond between the D-mix and old plaster seperated...
cracked within it's self..
had to go back on my dime and redo everything in 5 rooms.... to include repaint....
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
bond between the D-mix and old plaster seperated...
I remember that D- from d-mix was against bonding agents.
david.
-------------------------------------------------------------------------------------------
eureka.
59185.8 in reply to 59185.7
Hi Marv.
The bonding agent can create big problems some times.
You can use it on new surfaces where you don't have the possible delaminating problem. The bonding agent can soften the previews paint and cause the paint to come loose......
..together with the d-mix.
I use it once and it turn out to be the best wall stripper.
The joint compound on the other hand is ...a bonding agent. This thing sticks to anything.
YCF Dino
Edited 12/10/2006 10:46 am ET by davidwood
I remember that D- from d-mix was against bonding agents.
the D-mix it self seperrated ...
no bonding agents. in any capacity, were used or injured in the making of these repairs...
bond between the D-mix and old plaster seperated
I eventually had two parrarell cracks at every repair instead of the original just one I had started with...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Bond here is the reference to the mechanical joint between the D-mix and old plaster...
not bonding agents..
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
I'm lost here. Go over the application and we can avoid the problem in the future.
david
truely lost or just somewhat bewildered???
at what point did you loose yur way???
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
I eventually had two parrarell cracks at every repair instead of the original just one I had started with...
Lost between the cracks? Me not you.
you was using the d-mix for what application and at what ratios?
are you saying to use D'mix???
I tried D-mix for old world plaster crack repairs...
I believe because of the dissimilarities in materials it gave me very poor results primarily being the DW compound as the culprit...
the up shot is I won't ever use D-mix in this application again because it was a very expensive redo... (5 rooms w/ cielings) I won't experiment using D-mix on something like this either.. to me it'd be too risky...
I'll stay with the proven methods that work well and make the client along with my wallet happy...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Edited 12/10/2006 5:18 pm by IMERC
Some people try to repair Fords with Chevy parts too.
I never did get a real handle on what he was saying...
kinda like the replacement part thread...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
Bond.
James Bond._______________________________________________________________
What would Scooby do?
" You tried D Mix and didn't like it?!!!!!"I don't like it either blue. Tried it once and found my way does the same job faster.
Sherwin Williams makes a product called "Builder's Solution" which is a high build 'surfacer'..Basically an extremely thick primer. They even advise that you can add joint compound to it to thicken it even more. It sprays on w/ an airless. Works great. No troweling or squeegeeing and no odd-sized coffee cups of PoP to worry about. A whole lot less trouble than d-mix, methinks.
Hmm, I would answer that but it would only be a half answer. ;-)
Yo say that DW mud is too dissimilar. Do you use patching plaster or plaster of paris?BruceT
Edited 12/5/2006 2:32 pm ET by BruceT999
not plaster of paris...
hot mud..
hot mud with sand added..
really large holes and cracks get the real thing..
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
"for hairline cracks use drywallmud or hotmud and repaint; your going to get new cracks anyway."I can attest to the fact that DW mud leads to the crack returning. We've just chalked it up as patina.
Nonono - you don't really want to make old plaster look like drywall, do you? You can get a nice finish skimcoating using the D-mix method, discussed at length in another thread, but it will look better than drywall - IMHOP!
**wondering how we went from "hairline cracks" to whole room renovations**
lol
whats the best way you know, to make old plaster look like a new house
tear it all out and new rock..
3/8 rock over...
replaster, spray generously with paint and back roll for roller print texture...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
If you don't want the cracks then it has to be taped. If there are hairline cracks everywhere then laminate with 1/4" rock or get fiberglass mesh in 3' rolls and skim coat the entire wall with that as your base. If you want to just tape the existing cracks, then do it with fiberglass mesh, and float it from there. Cracks return unless treated right. If you want a plastered room and the look of plaster, then tape the cracks and live with what is. A plasterer will tell you to skim with an entire mesh coat or demo and start fresh.
I'm in the middle of plastering just such an animal right now in fact for an old customer of mine.
There's plaster (brown, lime and guage), and there's joint compound. Two different animals. Then there's all the others that lie in between.
michael,
i have a good friend who had been a painter and wall paper hanger for 20 years.
when he married a doctor he retired from the trade for a tougher stint as "mr.mom" to their new family
when he was a paper hanger-we always thought him to be a bit obsesive/compulsive/anal-retentive?---- at any rate, not to long ago he showed me a room in his house( old house,small town)------- hairline cracks in the plaster. He installed some kind of material----- sort of a cross between a wall canvas and a mesh---- then re-painted.
i thought it looked great- there is a texture to it so if you want a glistening smooth surface it's not for you-- but if you like a little texture it might be just the thing.
stephen
my guess it was this stuff
http://www.spec-chem.com/nuwal/index.htm
I have used it in a couple of rooms on badly cracked plaster and in over 10 years not one crack has come back. I swear by it, great stuff.
Go back to the #2 post from Dovetail. He pointed out the main secret to patching, to prevent shrinking crack patching. It is not dissimilar patching compounds that prevents bonding nor the type of the patch.
The reason why your patches crack, shrink or reappear is that you ALL forget to wet or mist the patching surfaces. A bone dry surface will suck out the moisture too quickly which reduces bonding and strength.