# llightweight vs all purpose.



## mark sr (Jun 13, 2017)

I almost always thin my mud because it makes it spread better. I try to avoid any heavy duty sanding. The smoother the mud is applied the less need for sanding, I don't really know if one ready mix j/c sands easier than another.


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## ClarenceBauer (Mar 4, 2005)

woodco said:


> So, I constantly float textured walls for wallpaper. If I use lightweight compound (whipped but unthinned) it goes on great and sands easy, but it is a little soft. The last time I used all purpose, it was a real b!tch to sand. Right smack in the middle fo the two would be a perfect for my application. Is there a way to make the all purpose a little bit softer, or lightweight a little bit harder? Does thinning it a little make it easier to sand? I dont thin because I do one coat, and I dont want it to shrink anymore than it already does.
> 
> Oh, and I am strictly asking about compounds, so please refrain from the 'technique' advice. I have a pretty good technique, and I can do plain walls pretty smooth, although not perfect.


Add some Ivory Lime to the All Purpose compound do not exceed 1 gallon container of DRY LIME per each full bucket of Compound. This mixture should trowel smooth no sanding required.
Just a question *why* not just use a compound that can be applied as smooth as glass no sanding required?


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## jeffnc (Apr 1, 2011)

I would not thin any more than the typical small amount used for skimming. It can't make it any easier to sand because the water simply evaporates leaving the exact same material behind, but just shrunken a bit more. Why do you have trouble sanding all purpose compound? I find it pretty easy.


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## JohnWL (Feb 28, 2019)

Adding a “small” amount of dish soap to USG AP green lid should reduce the density a bit, and I do stress adding only a small amount. The addition of too much soap can cause the fillers to become unbound when re-wet during priming resulting in the AP delaminating from itself.


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## Gymschu (Dec 12, 2010)

@woodco, years ago I worked with a husband and wife team of paper hangers and they had something special they used to float textured walls. It wasn't joint compound per se but it was the same consistency. If I'm not mistaken, it had a vinyl type additive in it that made it spread easier and to be truthful, I don't recall them doing much sanding. I wish I had paid more attention. They were highly respected and hung untold amounts of commercial vinyl. So, what I'm saying is that there is a product or was a product that existed to fill the need.


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## woodco (Jun 11, 2017)

jeffnc said:


> I would not thin any more than the typical small amount used for skimming. It can't make it any easier to sand because the water simply evaporates leaving the exact same material behind, but just shrunken a bit more. Why do you have trouble sanding all purpose compound? I find it pretty easy.


For a skimmed wall, all purpose is significantly harder to sand, at least it was the last time I used it... It just makes me wonder whats different about lightweight that makes it easier to sand... If I could replicate that with all purpose, to a lesser extent, I'd be happy.


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## woodco (Jun 11, 2017)

ClarenceBauer said:


> Add some Ivory Lime to the All Purpose compound do not exceed 1 gallon container of DRY LIME per each full bucket of Compound. This mixture should trowel smooth no sanding required.
> Just a question *why* not just use a compound that can be applied as smooth as glass no sanding required?


Well, Im only doing one coat over sometimes pretty rough texture. I try my damndest to do it as smooth as possible, but im not that good, apparently. Every taper I know that can do it without sanding has to do two coats.


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## JohnWL (Feb 28, 2019)

woodco said:


> For a skimmed wall, all purpose is significantly harder to sand, at least it was the last time I used it... It just makes me wonder whats different about lightweight that makes it easier to sand... If I could replicate that with all purpose, to a lesser extent, I'd be happy.


Lightweight AP has less limestone and more perlite than regular AP making it easier to sand..also, hollow microsphere fillers are used in lightweight joint compound to make it lighter & less dense than regular AP. Adding some soap to regular AP will result in a lighter/less dense compound which won’t shrink as much, plus will allow for a smoother application & less air bubbles by reducing surface tension.


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## ClarenceBauer (Mar 4, 2005)

woodco said:


> Well, Im only doing one coat over sometimes pretty rough texture. I try my damndest to do it as smooth as possible, but im not that good, apparently. Every taper I know that can do it without sanding has to do two coats.


Ok so you want a high build compound.
Delete adding Lime & replace the Lime with Gypsum perlite Plaster also know as Structo-Lite.
Sift the Structo-Lite using a screen wire & add to your All Purpose compound NOTE THIS will make the compound a setting compound you should be able to trowel this smooth, after the material has set to thumb print hardness to assist in smoothing it out use a spray bottle with water & mist as you trowel it.


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## woodco (Jun 11, 2017)

ClarenceBauer said:


> Ok so you want a high build compound.
> Delete adding Lime & replace the Lime with Gypsum perlite Plaster also know as Structo-Lite.
> Sift the Structo-Lite using a screen wire & add to your All Purpose compound NOTE THIS will make the compound a setting compound you should be able to trowel this smooth, after the material has set to thumb print hardness to assist in smoothing it out use a spray bottle with water & mist as you trowel it.


Thank you for that info. I trust what you're saying, but for my purposes, setting compound complicates my job too much. When I float walls, im in and out of the house in about an hour, hour and a half. I work with a 1" nap roller out of a 5 gallon bucket, usually just doing one wall, or a bathroom. I put it on the wall, and I scrape it off, point a fan on it, clean up, and tell the homeowners I will see them in the morning. If Im lucky, I have one or two other floats to do that day, then spend the next three days hanging paper on them. When I come back, I spend about 20 minutes sanding the wall, and get primer on it ASAP. Hang paper a couple hours later. 

Lightweight works great for this. The one problem is that its a little soft. Would it be okay to mix lightweight and all purpose? Im gonna try the bit of dishsoap like suggested above first though.


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## jeffnc (Apr 1, 2011)

Well, maybe LIghtweight is easier to sand, but I guess my point is, standard compound is so easy that it doesn't make any relevant difference to me. I've skimmed walls with it and not thought anything about any trouble when sanding it.


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## mark sr (Jun 13, 2017)

woodco said:


> Would it be okay to mix lightweight and all purpose?


I don't recall ever mixing lightweight with all purpose but there shouldn't be any issues in doing so [not sure it's worth the effort] I have mixed regular joint compound with a setting compound several different times with no issues.


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## JohnWL (Feb 28, 2019)

When floating walls to receive wall-coverings, I personally wouldn’t mess with the joint compound’s chemistry by adding a setting-type compound, perlited plaster, admixtures, or even soap, although I’ve probably installed hundreds if not thousands of linear yds of wall coverings over soaped mud installations done by drywall contractors w/out any issues. I’d hate the thought of having the joint compound or primer delaminate due to having added something not in accordance with the manufacturer’s PDS.

Have you considered just trying a mid-weight joint compound?


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## ClarenceBauer (Mar 4, 2005)

JohnWL said:


> When floating walls to receive wall-coverings, I personally wouldn’t mess with the joint compound’s chemistry by adding a setting-type compound, perlited plaster, admixtures, or even soap, although I’ve probably installed hundreds if not thousands of linear yds of wall coverings over soaped mud installations done by drywall contractors w/out any issues. I’d hate the thought of having the joint compound or primer delaminate due to having added something not in accordance with the manufacturer’s PDS.
> 
> Have you considered just trying a mid-weight joint compound?


Yes the manufacture of the Joint Compound does state " DO NOT ADD ANY OTHER PRDUCT TO THIS PRODUCT". 
My info for using Joint compound & Gypsum or Lime comes from my Plaster book dated 1897. Examples of some of the mixes.
Lime mixed with Corn Flour & Ground Rice.
In Greece - Italy they used Lime, Eggs, Butter Milk , Sand, Fresh Butter & water for a marble-like appearance.
Lime was also mixed with Jaghery .
In 1571 Lime , 350 Eggs Sugar & Gluten of Rice (page # 103)
Page #74 year 1802 Lime, Clay Oxide of Iron.
The year 1108 Whites of Eggs , Wort of Malt, & Lime.
1756 Lime & Cement consisted in a combination of CLAY with CARBINATE of LIME.
Selenitic Clay = Lime Clay & Sand.
Being Joint Compound is made up using Attapulgite & Kaolin clay it is compatible with other Gypsum & Lime products.
Other things that can be added to Lime Plaster.
The water from the root of Wort, potatoe water & other starches.


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## JohnWL (Feb 28, 2019)

Great stuff! What’s the book’s title? I’d love to pick up a copy if it’s still in print.

I’ve added a fair share of somewhat unorthodox ingredients to hard plasters, and have also added USG Perlited Plaster to USG AP premix at or more than your recommended proportions for doing faux dimensional bricks on walls.

Unlike paint, wall-coverings do however add mechanical stresses to the joint compound/substrate which can sometimes cause the primer to shear off the compounds, or to cause the compounds to shear off a previously painted substrate. A lot of the heavier and more rigid natural fiber wall coverings have a tendency to seasonally expand & contract, sometimes resulting in the above mentioned shearing and puckering at seams. I’ve seen it happen all too often. I’d be less inclined to add something to AP not in accordance with the manufacturer’s spec under an expensive wall covering, if in the event it did compromise to material resulting in some type of failure.


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## jeffnc (Apr 1, 2011)

JohnWL said:


> Have you considered just trying a mid-weight joint compound?


This might be the best answer. I've never actually seen this stuff available, but I don't frequent the big specialty suppliers. It specifically mentions skim coating. It is listed on both Home Depot and Lowe's websites, but is not available from either one.






Sheetrock® Brand Midweight™ Joint Compound | USG


Sheetrock® Brand Midweight™ Joint Compound's vinyl formulation makes it an ideal drywall mud for finishing over fasteners, bead and trim.




www.usg.com


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## ClarenceBauer (Mar 4, 2005)

JohnWL said:


> Great stuff! What’s the book’s title? I’d love to pick up a copy if it’s still in print.
> 
> I’ve added a fair share of somewhat unorthodox ingredients to hard plasters, and have also added USG Perlited Plaster to USG AP premix at or more than your recommended proportions for doing faux dimensional bricks on walls.
> 
> Unlike paint, wall-coverings do however add mechanical stresses to the joint compound/substrate which can sometimes cause the primer to shear off the compounds, or to cause the compounds to shear off a previously painted substrate. A lot of the heavier and more rigid natural fiber wall coverings have a tendency to seasonally expand & contract, sometimes resulting in the above mentioned shearing and puckering at seams. I’ve seen it happen all too often. I’d be less inclined to add something to AP not in accordance with the manufacturer’s spec under an expensive wall covering, if in the event it did compromise to material resulting in some type of failure.


The book I have is Plastering Plain & Decorative.
By William Millar 
Published in 1897 by B.T. Batsford, High Holborn, London.
I have had this copy for the last 30 years cost than was $ 750.00 
You can now purchase a hard copy from Donhead Publishing Ltd. @ a cost of $150.00 to $200.00


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## jeffnc (Apr 1, 2011)

Man that is HARD CORE old school.


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## ClarenceBauer (Mar 4, 2005)

jeffnc said:


> Man that is HARD CORE old school.


 Look at what OLD SCHOOL can do ( BEFORE )


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## ClarenceBauer (Mar 4, 2005)

ClarenceBauer said:


> Look at what OLD SCHOOL can do ( BEFORE )
> View attachment 637612


 After OLD SCHOOL completed


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## ClarenceBauer (Mar 4, 2005)

ClarenceBauer said:


> After OLD SCHOOL completed
> View attachment 637615


Another picture of how Old School can use the old method to make it look original. 








This is the same picture that is in the Master of Plaster web site.


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## woodco (Jun 11, 2017)

If I new there was such a thing as midweight, I definitely would have tried that before coming on here. IDK where to get it though.


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