Applicator Information & Tips

FirmoLux™ is an All-Natural Authentic Italian Lime Plaster System1 that is the plaster and choice for Architects, Designers and Applicators worldwide.  We are the “Art of Venetian Plaster.”

Thank you for taking the time to learn about our products. Before you find out how great they are, we would like to offer you some simple information about our system, which will make you understand why and how our products work so well with each other. 

There are many professionals who offer various levels of experience when working with “Venetian Plaster.”  The difference between FirmoLux™ and the Venetian Plaster you know today is that the FirmoLux™ System for application is designed to make your experience with our product more enjoyable, easier to use, and ultimately more profitable. This System is meant to save you time, money and add value to your work and company.


What is “real” Venetian Plaster?

Today, there are a number misconceptions and ideas about Venetian Plaster.  Modern day “Venetian Plaster” and we use that term loosely, means many different things to many different people.  You might have heard the saying

“You can paint white stripes on a black horse and call it a Zebra, but it’s still a horse,” or was it paint black stripes on a white horse…I could never get it straight!

Well you can also put white plaster in a white plastic bucket and call it “Venetian Plaster” but in most cases it isn’t. There are many “so called” Venetian Plaster experts who really don’t know what real Lime Plasters are supposed to do and how they operate.  There are many companies that sell products under the label “Venetian Plaster.” 

If you sold one of these buckets to an artisan living in Venice 200 years ago, they would dump the bucket into the canal along with the salesman that sold it to them.

Modern Day Venetian Plaster (and just because it’s made it Italy doesn’t make it real) is a term used for many products that are supposed to “act” like plaster but should be called Faux2 Venetian Plaster”. Why? Because that’s really what it is!  These manufacturers are trying to improve upon nature.  They use the same products used in Italian Lime Plaster but add synthetic materials to assist in making the product act and look like Italian Plaster.  In the end, it’s a product that does not have the design or natural traits that allow it to work for the applicator and ultimately, is not in the customer’s best interest.  Faux Plaster will not age as gracefully, nor have the same redeeming attributes of plaster.  Also, you will find that the cost will often be greater than real authentic Italian Lime Plaster.

It is our goal to try and educate our customers so that using the FirmoLux™ system of application will make their experience with plasters more enjoyable and rewarding.  FirmoLux™ is unique to the industry since it is a true, all natural Italian Lime Plaster with less than 2% resins. This allows us to be a Green Building Product3 and environmentally friendly.

Our primers and plasters are made to be used together, and there is a “system” or logic as to why and how they work so well. 

Consider each line of our plaster like a puzzle piece.  Since they are all natural products, the puzzle pieces are made to be put together using the molecular similarity of the properties in the product which will enable you to put the puzzle together smoother & faster giving you the picture you want.

Now consider products that are not designed naturally and have no “system or logic” and molecularly are not designed to work together and sometimes fight the process.  These products have some of the same materials you’ll find in our product but they also include vinyl polymers, acrylics, cement and other chemicals or fillers. 

You’ll find that it’s difficult to put the wrong shaped piece into another puzzle piece, but if you work at it sometimes it will fit.  However, when you look at it, it just doesn’t seem to look right. Consequently, it makes your job harder, creates inefficiency and the end product is not what you set out to achieve.  Perhaps the finished result might have looked better if you had help from nature.

To understand this “system”, you need to understand that our products are produced with granules of minerals and aggregates that are different sizes for each product; in other words, our Marmorino Berlina™ has a granulation size of about 300 microns for all the minerals in that entire bucket, where a different product will have a different size granulation of minerals.  Why does this matter?

It’s important to understand that the fundamental properties and idea of FirmoLux™ is to maximize your ability to work with a product that is part of a system of products.  Granulation sizes, when dealing with natural plasters, are important because this is what makes your job easier. Understanding what kind of plaster is to be used for the type of effect or job that you are doing is ultimately going to make you an authority and expert to your clients that value your expertise and reward you for your knowledge and experience.

When we produce our product, we put the minerals through giant sifters like the one mom used to sift flour through when she made bread or cookies.  In fact, we refer to the lime as “Flour” when preparing to mix it with other aggregates to manufacture our products. We have different size screens or sifters that will filter the minerals to only allow the granule size we want in that product to pass into our mixing tanks. Those granule sizes are then all the same dimension.  In other words, all the granules of material in the product we are making are the same size or thickness which allows us to blend our product with like sized material.  We measure these granules in microns or micrometers4.

Let’s talk now about our products and the best system technique5 to use them.

First, remember we talked about Microns, and how every product’s granulation size is different, and measured in microns.  Our products range in microns from 3-700 microns in size. (0.003 – .700 mm).  The smaller the micron size the smaller the granulation, the larger the micron the bigger the granulation.  Feel the consistency of the MicroPrimer™ and you’ll see it feels almost like a cream and you can barely feel any granules. Then feel the Grassello and you feel very small grit.  Now feel the Intonaco Mezzo™ or Marmorino Piatto™ and you’ll feel and see the granulation because they are the largest.

Now let’s talk about that puzzle again.  Have you ever tried to put a piece in the puzzle that is not meant to go there? If you are determined you can make it fit, but:

  • it won’t be easy to put it in the puzzle and
  • It won’t look as good when you’re done.

Now let’s assume we have two pieces of that same puzzle that are a perfect match and the puzzle piece slips into place just right.   This is the same principle for Italian Lime plasters, using the granulation sizes, allowing the plaster to work together as a system or team of products.

If we were to look at plaster under a high-powered microscope, you will see:


The first coat of product works best when you use a larger micron product, followed by the 2nd coat using a smaller micron product.  Your final product and finish will exhibit a complete and polished look.  It also works well if you use the same micron product for your base and finish coat, allowing for a harmonious feel and texture.

Introduction to Application Technique


  • If you mix your own colors to blend into your products, then we suggest using colorants that are made for lime or can tolerate a level of pH13.   Colors with Iron Oxides work the best.  Remember that lime is a living organism, and the molecules are moving and working all the time once it’s applied to the wall.  Using the correct type of colorants made for lime is important, especially in an exterior application where you have exposure to weather and the sun’s UV rays.  Color can also shift over time if the colorants are not fresh, designed for lime and mixed properly.

When involved in a job where there are several buckets of the same color, it’s important to “Box”6 your product to achieve a more even color.


  • Prepare your wall to make sure it is clean from any dust or dirt particles, especially from any oil or grease. If an application is over existing painted surface, clean surface and remove any paint that is flaking and repair the wall of any damages or holes.
  • The most common and traditional method of application is when you’ve finished preparing your wall, apply your primer either diluted or undiluted depending on the type of primer and the substrate condition.  (See section on Primers). 
  • Apply primer and allow the primer to dry for at least 12-24 hours before application of any finish plaster.

Plaster 1st Coat

  • Your primer is already dry and you have prepared the plaster for the application (stir plaster well before using). When you tint your plaster with colorants, be sure to mix well allowing for consistent color throughout.
  • While using a stainless steel finishing trowel7, you will be laying the plaster down in a thin coat trying to level the wall at the same time.  If the wall or surface is porous (e.g. brick), push the product into the surface as you apply your first coat. 
  • First coat applications can use a medium to large trowel, depending on the comfort of the applicator.
  • You will apply the most plaster on your first coat, but be careful not to apply too much product, which will not give you an even leveling coat. 
  • A result of putting too much product down on your first coat, especially with products that have a value of 300 or more microns, is that you will begin to see cracking on the surface (cracking like on an old masterpiece) as it dries which we call “shrinkage or reduction8”. 
  • If this occurs begin applying less plaster on future applications. You can reapply over those areas pushing the product into the surface.  Some applicators mist the area to dampen it so that they can get a better joining of the products and will come with experience and with knowing your products.
  • After the 1st coat has dried or almost dry, you can then begin to apply your 2nd coat.

Plaster 2nd Coat

  • While applying the second coat, either with a smaller Micron product or the same size micron product, you want to push the product into the 1st coat.  Never push hard if the 1st coat is not completely dry.  Some applicators will dampen the 1st coat with a sprayer to help application work easier but it’s not necessary.  These are application techniques you’ll develop when you begin to learn your products.
  • A result of applying product incorrectly is if you see the plaster rolling up behind the trowel as you’re applying the 2nd coat. It’s normally a sign that the 1st coat is still too wet or that it has been burnished and is too smooth.  This is different for each product.  If this occurs and it pulls the plaster off the 1st coat, then a patch job is necessary to repair that damaged area. 
  • Patching is better learned on sample boards.  Trying to recreate problems is sometimes the best way not to ever have them.  Remember, practice and learning about your products will make you the professional and you’ll stand out from the rest of the competition.
  • Before the 2nd coat dries and about 20 minutes after applying the 2nd coat (if the 2nd coat is your last coat), go back over that surface and “close off” the finish. Closing the surface is a procedure that is used to give finality to the finish and ultimately a complete look.

Plaster Closing

  • Closing9 the surface is a procedure that is used to give finality to the finish and ultimately a complete look.
  • You take your clean trowel with no plaster or dirt on it and push the plaster lightly into different directions. Up and down side to side and bottom to top.  You will see a “cream” come from the surface that is caused by melding the producttogether and giving it a smooth finish.  DO NOT reuse this cream and put in a separate container and NEVER MIX the “cream” with your fresh product that you are using to apply.

Plaster Burnishing

  • Burnishing10 is a term that is used to give a smooth and polished look to your finish. It is not always a desired look nor does it have to be done.   This is a procedure that will be determined when the product texture is determined in advance.
  • Burnishing is when you use your trowel at about a 45° angle and honing your trowel over the semi-dry surface. 
  • This is a procedure that you most certainly should practice on sample boards.  We never suggest practicing any procedure on your client’s walls.
  • When you burnish your finish, you will begin to see high degrees of shine and gloss. Remember that the smaller the micron and the more lime and marble in a product, the more shine. The best products to burnish are any of the Marmorino products, and especially the Grassello.
  • The Metallic plasters are not designed to be burnished, however burnishing them will provide for a different look.  The metallic plaster naturally is more of a satin  finish looking product.
  • The Intonaco Mezzo can be burnished, but the results are more matt along with more design interest.

Sealers and Waxes

Penetrating Sealer11

  • We recommend the use of sealers for exterior walls especially walls that can expect extreme weather and exposure.  The use of sealers on interior walls is suggested in splash areas like behind kitchen sinks, near stoves and ovens, and in bathrooms near or in showers stalls where excessive water could damage the finish.
  • We don’t recommend sealers to be used for all cases over lime plaster as it defeats the purpose of the breathability of the product.
  • We recommend an American made extra strength penetrating sealer that we sell.  This sealer is a masonry sealer and is natural / neutral in color.  It is a penetrating sealer that can be used on exterior and interiors surfaces.  It is made for a pH13 level that is found in lime.


There are different waxes that are used and favored by different applicators and FirmoLux™ distributes what we feel are the best designed for lime finishes.  Our waxes are imported and manufactured in Italy.  We have a liquid wax called DécorWax™ and a hard wax called Spatula Wax.  Each wax has different characteristics and application styles.   Most waxes are not used on exteriors, but we have heard of applicators using them to help with design and color enhancement before applying sealers.

DécorWax™ and Natural Bee’s Wax
  • DécorWax and natural bee’s wax are liquid waxes that come in 1 Liter bottles or jars. Both can be color tinted to add effect to your finish application and is sometimes used to correct or change the color of the final finish. 
  • The wax will always deepen the color and add contrast to your finish, so it is highly suggested that when showing samples to your clients that they see samples with wax if you plan to use wax on your finished wall. 
  • This wax is applied with a sponge, soft cotton rag or roller and brush.  Wipe off any excessive wax immediately to avoid streaking.  The wax will penetrate the plaster on porous finishes, and the yields will vary depending on texture and products used.
  • Use a clean cotton rag or cheesecloth to polish the wax after drying, and do not allow the wax to dry too long before polishing.

Spatula Wax
  • Spatula Wax is a thick petroleum based wax that is applied more commonly with a trowel or smooth spatula type trowel.  (make sure edges are smooth and rounded, and that corners are rounded if you use a spatula)
  • When Spatula wax is applied is pushed into the plaster and troweled on like plaster and work time is much faster.  It is important that after 10-30 minutes from application time, that you wipe off any excess wax that is on the surface and to hand polish


  1. FirmoLux™ Products are meant to be used together as a System, making them work harmoniously to archive the ultimate design and luxurious look and feel for your project.     
  2. Faux is a common French word used in the English language and its translation means Fake or Imitation.  The word is, and commonly used in the decorative and painting industry.
  3. A Green Building Product is a product that has a very little environmental impact and is mostly a natural building substance.
  4. Micron or Micrometer (µn), 1 micron (µn) is 1:1000 of a millimeter (0.001 mm) and 100 microns is equal to 0.1mm (1/10 of a millimeter). A human size hair or a grain of sand is about 150 microns in diameter.
  5. System Technique. FirmoLux plasters are system products designed to work together so that the applicator will have a better application experience, as well as being able to create and endless amount of textures that will make you stand out from other Italian Plaster Applicators in your market.  Remember, the simple rules will be the start of a good working knowledge of Authentic Italian Lime Plasters.
  6. Boxing your product is taking an empty bucket and taking half the contents of one bucket and the mix the buckets together so you have a more uniform or consistent color.  Usually, box 4-5 buckets so the same color would work well especially if they are large walls.
  7. Stainless Steel Finishing Trowels are specially designed for Italian Lime Plaster finishes.  Stainless steel is important because lime is caustic and will cause normal metal trowels to rust and ruin your application.  Finishing trowels have a curved edge so it is better to push the product into the surface and aids in burnishing.
  8. Shrinkage or reduction is a result of the plaster drying and the spaces between the larger microns of product evaporate, dry or shrink to fill in the space.
  9. Closing is a term for finishing the surface coat and can be done before burnishing.  Closing is not always necessary in every application but is dictated by the texture and design to be achieved.
  10. Burnishing is a term that is used to achieve a high polished or glassy/glossy look on the finish.  Burnishing is not necessary for all application and is only used when the desired texture is indicated.
  11. Penetrating Sealers are not necessary for most interior applications but recommend for exterior applications.
  12. Waxes are not necessary for most interior applications but can be used to enhance the design look and for extra protection.
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