Preparation and Sanding

GF Milk Paints are self-sealing so it is not necessary to use primer.

You may use a white pigmented stain-blocking primer if you need to cover grain, paint light or white color on dark wood, or if you're painting a wood that is known to bleed, such as pine or mahogany. We recommend using General Finishes Stain Blocker, Kilz or Zinsser white pigmented shellac-based primers.

Warning: sometimes it is impossible to block bleed through. Always test. Not all projects with existing finishes are candidates for light paint colors. If this happens, start turning your thoughts to Lamp Black Milk Paint - that will cover a lot of problems.

We recommend the following technique:

1. Spray your project inside and out with Ozium Sanitizer.
2. Place a box or bowl of charcoal briquettes inside your project.
3. Cover your entire project with plastic and let it sit for 24 hours.
4. Clean your project with a Scotch Brite pad and a 50/50 mix of denatured alcohol and water. 
5. Sand the surface with a 150 or 180 grit sanding pad. We recommend Softback Sanding Sponges.
6. If there is still lingering odor, a coat of shellac may help.

1. Spray your project inside and out with Ozuim Sanitizer.
2. Place a box or bowl of charcoal briquettes inside your project.
3. Cover your entire project with plastic and let it sit for 24 hours.
4. Clean your project with a Scotch-Brite pad and a 50/50 mix of denatured alcohol and water.
5. Sand the surface with a 150-grit or 180-grit sanding pad. We recommend Softback Sanding Sponges.
6. If there is still a bit of lingering odor, a coat of shellac may help.

Never guarantee a finish on this era of furniture. Inform your customers of this issue and steer customers away from using light colors. Many mahogany pieces from the late 1920's to early 1930's have an aniline dye lacquer finish which can bleed through no matter how many times you paint or prime over it. Although ideal coverage over an aniline dye lacquer can never be guaranteed, the following two products have been known to minimize bleed through:

1. A stain blocking primer such as General Finishes Stain Blocker or Zinsser B-I-N
2. A shellac seal coat will usually stop most of the bleeding

Note: If you are trying to cover red mahogany with a white you may never be able to stop the bleed through. Stain Blocker is most likely to stop the bleed-through of all options listed above because it was specifically engineered to block the most persistent bleed-through.

Tips from GF:

1. Never guarantee a finish on this era of furniture. Inform your customers of this issue and steer customers away from using light colors.
2. Clean the project and apply 2 coats of General Finishes Stain Blocker with a brush, roller or by spraying. The first coat will absorb contaminants in the wood, causing a color change during the first application, and the second will seal the contaminants. More information regarding Stain Blocker here.
3. Another primer alternative is Zinsser B-I-N.
4. Use a dark paint color - there are some pieces that will never work with al light paint.
5. If none of this works, we recommend that you strip and refinish with a penetrating oil stain followed by a clear coat.

Stripping Recommendations:

1. Use a good quality citrus stripper or a soy gel stripper as they are more gentle than traditional chemical strippers.
2. Remove any remaining finish with 150 grit sandpaper.
3. Once you have removed the old finish, wash the piece down with a 50/50 blend of denatured alcohol and water to remove any residual oils and waxes.
4. Once these stages have been completed, it is safe to use any type of wood stain to restore the original look of the piece.

Although some companies promote their products as "no prep", that is nonsense. If you skip this step the finish can fail.

General Finishes standard for a good finish is it must adhere well and stand the test of time. 

1. PREP CLEANING:

Cleaning an existing finish removes dirt, grime and many common contaminants such as oil from hands. Dirt, grime, and oil prevent good adhesion causing the possibility of chipping, peeling and flaking - all signs of a failed finish.

We prefer a 50|50 mix of denatured alcohol and water because it does not contain phosphates, is inexpensive, readily available and does not require rinsing.

You can also use ammonia as a cleaner when using oil-based finishes. We do not recommend using ammonia with water-based finishes as it can cause the finish to blush (turn white).

50|50 water|bleach or 50|50 water vinegar solutions can be used as well - be sure to rinse with a warm, wet cloth and let the project dry.

In cases where the project has a lot of buildup, we recommend scrubbing with a detergent such as Spic and Span first, followed by a rinse, and then by the 50|50 mix of water and alcohol. Let your piece dry thoroughly.

You can use commercial furniture cleaners such as TSP but check the label for phosphates - they will leave a residue behind that requires rinsing.

2. PREP SANDING:

The most critical part of finishing a piece of furniture happens before you open a can of stain or paint - it starts with the sanding. Prep sanding an existing finish further cleans the surface, removing built-up dirt, grime, and oil from hands.

Prep sand an existing finish with a 220 sanding pad.

3. BE CAUTIOUS OF CONTAMINANTS

Contaminants from dusting sprays that contain silicone will also impact the appearance and adherence of a finish - silicone is almost impossible to remove. Oil soaps and wax can also cause adhesion failures.

The most critical part of finishing a piece of furniture happens before you open a can of stain or paint - it starts with the sanding. Sanding is critical to creating a smooth surface. Use the following sanding sequences for new wood:

PAINT

For wood that is going to be painted, use 120-grit, followed by 150-grit.

WATER-BASED STAINS

• For closed-grain woods (such as Cherry, Pine, Maple, Birch or Alder) that will be stained with water-based products use 150-grit followed by 220-grit.
• For open-grain woods (such as Oak, Ash, Mahogany, Parawood) that will be stained with water-based products use 120-grit, followed by 150-grit, then 180-grit.

OIL-BASED STAINS

• Sand closed grain woods with no finer than 180-grit.
• Sand open grain woods with 120-grit followed by 150-grit, then 180-grit.

CLEAR-COATED WITH WATER-BASED PRODUCTS

For wood that will be clear-coated with a water-based topcoat, use 120-grit, followed by 150 or 220-grit.

CLEAR-COATED WITH OIL-BASED PRODUCTS

For wood that will be clear-coated with an oil-based topcoat, sand up to 150-grit.

Do not over sand with the final grits. You will create a surface that is so smooth it will not accept a finish.

Instructional Video: How to Prep Sand New or Raw Wood

You can clean your project with ammonia only if you will be working with an oil based finish. Ammonia can cause a water based finish to blush or turn white. If using a water based finish, a 50/50 mix of denatured alcohol and water is best.

Note: Avoid using oil-soap or silcone-based daily cleaners such as Pledge, Endust or Murphy's Oil. These types of products can contaminate your finish, preventing further applications of paints or topcoats in the future.  

Yes. Denatured alcohol is the solvent used in Shellac. A 50/50 mix is commonly used when conditioning wood before staining.

Never use mineral spirits to prep clean before applying water-based finishes.

You can correct this problem by cleaning again with a 50:50 mix of denatured alcohol and water.

Let your project dry 24 hours before applying water-based products.

If your current finish is chipping, it is failing to adhere correctly. The adhesion problem could be caused by several reasons:

1. Improper preparation: Cleaning an existing finish removes dirt, grime and many common contaminants such as oil from hands. Dirt, grime and oil prevent good ahesion causing the possiblility of chipping, peeling and flaking - all signs of a failed finish.
2. Contaminants from dusting sprays that contain silicone will also impact the appearance and adherence of a finish - silicone is almost impossible to remove. Oil soaps and wax can also cause ahesion failures.
3. The previous paint was a "chippy style" paint, such as an original casein based milk paint that does not contain the necessary resins for high durability

We would not recommend applying any of our products over a failing finish, because the underlying finish could continue to present adhesion problems. Your only recourse for a good result is to remove the current finish by stripping and sanding.

Rubbing alcohol is a generic term and is usually manufactured with isopropyl alcohol.

Different brands of denatured alcohol contain various denaturants such as bittering agents. The purpose is to discourage recreational human consumption by including additives that are bad tasting, bad-smelling or nauseating.

A 50/50 mix of either rubbing alcohol and denatured alcohol will work for prep cleaning. Both have good solvents that will remove dirt and grime.

Although some companies promote their products as "no prep," that is nonsense. If you skip this step the finish can fail. General Finishes's standard for a good finish is it must adhere well and stand the test of time.

1. Prep Sanding
   • The most critical part of finishing a piece of furniture happens before you open a can of stain or paint - it starts with the sanding. Prep sanding an existing finish further cleans the surface, removing built up dirt, grime and oil from hands.
   • Prep sand an existing finish with a 220 sanding pad.
2. Prep Cleaning
   • Cleaning an existing finish removes dirt, grime and many common contaminants such as dusting sprays, cleaners and oil from hands. Be especially careful in areas where hands are likely to touch (near knobs on cabinets and the tops of bannisters, for example). Dirt, grime and oil prevent good adhesion causing the possibility of chipping, peeling and flaking - all signs of a failed finish.
   • We prefer a 50/50 mix of denatured alcohol and water because it does not contain phosphates, is inexpensive, is readily available and does not require rinsing.
   • You can also use ammonia as a cleaner when using oil based finishes. We do not recommend using ammonia with water-based finishes as it can cause the finish to blush (turn white).
   • 50/50 water/bleach or 50/50 water/vinegar solutions can be used as well - be sure to rinse with a warm, wet cloth and let the project dry.
   • In cases where the project has a lot of buildup, we recommend scrubbing with a detergent such as Spic and Span first, followed by a rinse, then by the 50/50 mix of water and alcohol. Let your piece dry thoroughly.
   • You can use commercial furniture cleaners such as TSP but check the label for phosphates - they will leave a residue behind that requires rinsing.
3. Be Cautious of Contaminants
   • Contaminants from dusting sprays that contain silicone will also impact the appearance and adherence of a finish - silicone may be impossible to remove. Oil soaps and wax can also cause adhesion failures.

This response is true of prepping and existing finish on furniture, but kitchen cabinets are more problematic because they are work areas where grease, steam, food splatters and oil from hands are common. Prep is basically degreasing and abrading the surface for better adhesion. Oil or substances on hands really show up on a failed re-finish around doorknobs and hands if the surface is not cleaned thoroughly.

Because of this, General Finishes believes there is no such thing as a "no prep" paint. We would be leading our customers down the path failure if we touted our products as such. Dirt, grime, oil from hands, wax, dusting sprays that contain silicone, oil soaps or wax prevent good adhesion causing the possibility of chipping, peeling and flaking - all signs of a failed finish. This is the number one reason we see for finish failure. The second is not allowing enough dry time.

The heart of the problem is that we often don't know what was used on the cabinets previously. If dusting sprays that contain silicone have previously been used, the risk of finish failure is high. There are no guarantees with silicone - it is almost impossible to remove. Here are our recommendations. It sounds like a lot of work because it is - charge more.

CLEANING AND PRIMING:

1. Scrub with a degreasing detergent such as Spic and Span or Dawn soap first. Follow with a thorough rinse to remove all the soap.
   
   WATCH this video about cleaning with Dawn detergent.
    
2. Clean with a 50/50 mix of water and denatured alcohol. Let your piece dry thoroughly.
   
   We prefer a 50/50 mix of denatured alcohol and water because it does not contain phosphates, is inexpensive, is readily available and does not require rinsing. You can use commercial furniture cleaners but check the label for phosphates - they will leave a residue behind that requires rinsing.
    
3. Scuff sand with a 320 Grit Klingspor Ultra Flex Sanding PAD (or 400 grit sandpaper) and remove the dust. There are other sanding PADS out there - just make sure the grit is not too aggressive or you man sand down corners and edges down to bare wood.
    
4. Put down a coat of General Finishes Sanding Sealer. GF Sanding Sealer can be used over cleaned and prepped existing finishes that will create a strong barrier with superior adhesion properties. The resin particle is larger so it builds fast, and finish sanding is a breeze.
   
   (Note: We cannot comment on other sanding sealers because several on the market state dry times that are so short that our paint and stains would fail.)
    
5. You can apply Gel Stain over the sanding sealer after 24 hours.
    
6. You can apply paint or water based stain over the sanding sealer after 3 hours.
7. You can apply a white primer over the sanding sealer if you want to color correct for a white paint.

OTHER CLEANING INFO:

• You can use vinegar, bleach or ammonia solutions, but our experience shows they are usually not aggressive enough for kitchen cabinets. We do not recommend using ammonia with water-based finishes as it can cause the finish to blush (turn white).
   
• Never use steel wool with water based products because the particles can become embedded and rust. Some alternatives are Klingspor Synthetic Wool and Merka Mirlon 1500 synthetic wool.
   
• Steel wool is still an acceptable option with oil-based finishes. GF recommends using oil-free 0000 wool from Liberon because it doesn't shred as easily as the hardware store brands.
   
• NEVER USE mineral spirits to prep clean before applying water-based finishes. You can correct this problem by cleaning again with a 50/50 mix of denatured alcohol and water. Let your project dry 24 hours before applying water-based products.

PROTECT YOURSELF
There are two ways to protect yourself:

1. Use a contract and have customers sign off on a warranty. It is extremely exhausting and frightening to be faced with a customer angry over a failed finish. You cannot warrant a finish over unknown substances. Here is a suggestion for your contracts:
   
   We cannot warrant finishes over an existing piece of furniture without knowing the history. If products containing silicone dusting powders, oil soaps or waxes have been previously used on the piece, they may contaminate a new finish and prevent adhesion. In these situations, it is best to strip and sand the entire piece. Occasionally, a previous wax finish or silicone may be impossible to remove.
   
   ______(Initials) I acknowledge that this piece has never been waxed/polished with a silicon-based dusting spray or cleaned with oil soaps.
   
   ______(Initials) I have no knowledge of waxes, silicone-based dusting sprays or oil soap products being used on my cabinets.
    
2. Take the most used drawer or door in the kitchen and test your finish schedule first. And charge for it.

Possibly - it will depend on the quality of the stripping and sanding.

If done correctly, and all of the existing finish is removed, the stain will penetrate the same as on raw wood.

If the sanding and stripping are incomplete, the grain and pores of the surface are sealed more, and will not accept stain as easily. More stain may be needed to accomplish the same color as on original raw wood, and longer dry times will be required, especially for thick stains, such as General Finishes Gel Stain.

Although both items are labeled as 220-grit, the pads are softer with a less aggressive scratch pattern.

With use, a 220-grit pad will soften very quickly to the equivalent of 400-grit sandpaper - making used pads ideal for finish sanding between layers of topcoat or prep sanding an EXISTING finish.

220-grit sandpaper is too aggressive for finish sanding but works well for the final round of prep sanding of open-grained raw wood such as Cherry, Pine, Maple, Birch, or Alder.

Pads are our favorite. The pads last a long time, can be rinsed to remove sanding residue and also have the benefit of being flexible, making corners and edges much easier to sand.

Putty comes in two forms, pre-colored or as a stainable wood filler designed to fill minor imperfection such as nail holes, cracks, and gouges in the wood surface. Putty will display stain a bit differently than wood, so it is not a "perfect" fix, but a good one.

The goal is to get the best possible color match to either the color of the raw wood or the color of your existing finish.

The easiest route is to buy a putty that is pre-mixed with color. Both Famowood and Timbermate make colors of putty in several shades. Famowood is available in both oil-based and water-based formulas. Timbermate is an interior grade water-based filler and comes in 13 pre-mixed colors.

Be careful to note if you are buying a solvent (oil) based putty or a water-based putty. Either will work as long as you observe opposing dry times when switching as you would do for finishes.

DRY TIMES:

• Water over oil: a minimum of 72 hours
• Oil over water: a minimum of 24 hours

If you cannot purchase the right color match, you can tint the putty with stain to create a custom color. For example:

• Timbermate is a water-based putty and can be mixed with water-based stains. We recommend darkening the putty with products such as General Finishes Water Based Wood Stain in Espresso or a General Finishes Dye Stain color.
• Famowood is an oil-based putty and can be mixed with oil-based stains. For example, you could darken the putty with General Finishes Gel Stain in Java.

TO USE:

• Prep sand your piece. If you are using with an existing finish, thoroughly prep clean and scuff sand your project first.
• Press wood filler into defected area.
• When dry, sand flush with surrounding surfaces after approximately 15-30 minutes, depending on temperature, depth of fill and whether the putty is oil or water based.

Finally, another good putty is Color Putty. They make both water and oil-based versions in ready-made colors. This is a soft putty that can be used AFTER the project is finished to fill nail holes or small imperfections.

ALWAYS TEST filler, stain and finish combinations on a small area before applying to your project.

Ideal Conditions are 70 degrees F and 50% humidity. Refinishing furniture in a space that is below or above the 65-75 degrees F range can lead to problems, and a space below 55 degrees F is definitely too cold.

WATER-BASED TOPCOATS

One issue caused by cold temperatures with water-based topcoats is the development of dimples in the finish called Orange Peel.

The colder your space it is, the longer you have to wait between coats. Cold temperatures slow the dry time and affect how quickly the finish will level, harden and cure. Our easy rule of thumb is; if it is cold enough to wear a sweater it is too cold to apply a water-based finish.

If you must apply WATER BASED TOP COATS in cool conditions, add General Finishes Accelerator to speed water evaporation from the finish. Make sure the finish and the surface of the piece you are working on are at room temperature. You can warm up the finish by placing the can in hot water for 5 minutes beforehand, and if possible, move the piece back into warmer temperature after applying finishes for the 7 days of cure time.

OIL-BASED FINISHES

Oil-based finishes are not as affected by cooler temperatures, but lower temps will still slow the oxidation of the finish. GF again suggests moving the piece back into warmer temperature after applying finishes for the 7 days of cure time.

You can apply oil-based finishes in as low as 60 degrees if necessary.

WARNING: Applying OIL BASED finishes near an open flame or combustible heater is VERY DANGEROUS. The mineral spirit mixes with fumes from kerosene, for example, creating an unsafe environment.

Conversely, if you are working in HOT, DRY climates any WATER BASE finish will dry faster. General Finishes Extender can be added to water based products to increase dry time in those situations.

Ideal temperature to store product: 65-75 degrees F. Garages are not a good place to store any finish.

NOTE: We have been asked whether it is OK to paint in a 50 degrees F shop if the paint is stored at a safe temperature beforehand, and the finished piece is moved into a room with a safe temperature to dry. This approach might work, but it's risky.

See video tutorial: Tips on Storing Leftover Finishes

MDF (Medium Density Fiberboard) is tricky because there are several grades of MDF and the quality varies.

If you cannot determine the quality of the MDF, play it safe and use best practices. The concern is with the edges and ends. The core of MDF is compressed sawdust, glue and resins so when you apply paint to those areas it soaks right up.

1. Sand the edges and ends very well with 150-grit sandpaper, then apply a light coat of filler (such as Timbermate water-based wood filler or even joint compound). That will seal the open pores, making it easier to obtain a smooth and consistent finish when painting. The sealing of the ends is even more important than wood because MDF will swell upon contact with moisture.
2. The front and back of MDF are pressed and sanding during production, but should also be primed with a primer such as Kilz, Bin 123 Primer, or either General Finishes White Undercoat or General Finishes Stain Blocker to ensure a better outcome. Then follow with two coats of paint. MDF is not as absorbent as natural wood, so wait 2 days between coats of paint or primer.
3. Also, MDF also tends to cast a brown color. If you are using white paint, you can apply a coat of a light gray paint such as General Finishes Seagull Gray Milk Paint first to counter the brown instead of primer, and then apply a few coats of white over it. Let each coat dry 2 days before adding the next.
4. If you can determine that the MDF is of high quality, White Undercoat, a lower price point, is sufficient.

Sanding Sealer can be used on MDF, but the better choice would be White Undercoat or Stain Blocker. Both build faster and would probably require one less coat than Sanding Sealer.

As always, we recommend that you test your procedure on a hidden area of your project to ensure the product adheres well and achieves the desired color.

Never use mineral spirits to prep clean before applying water-based finishes.

You can correct this problem by cleaning again with a 50/50 mix of denatured alcohol and water.

Let your project dry 24 hours before applying water-based products.

White haze can develop when preparing an existing lacquer finish for re-coating. The haze needs to be removed before applying another finish.

To correct during oil based applications such as Gel Stain, sand lightly with sandpaper or a gray Scotch-Brite pad and then wipe down the surface with mineral spirits. Once the mineral spirits has dried completely, apply Gel Stain.

To correct for water-based applications, just sand lightly or scrub with a gray Scotch-Brite pad and wipe off the dust. Never use mineral spirits when using a water-based finish.

No, because the particles can become embedded and rust. Some alternatives are Klingspor Synthetic Wool and Meka Mirlon 1500 synthetic wool.

Steel wool is still an acceptable option for oil-based finishes. GF recommends using "oil-free" 0000 wool from Liberon because it doesn't shred as easy as hardware store brands.

Citrus strippers such as CitriStrip have a wax in them to keep the product from drying out after it's applied to the surface. Mineral spirits is recommended after the stripping solution because it's important to break down those waxes before getting started. However, mineral spirits is not compatible with water-based products.

On projects where a water-based product will be used, we recommend cleaning with Acetone which evaporates quickly and removes any residue. After using Acetone, wash with the 50:50 mix of denatured alcohol and water.

If you have already cleaned with mineral spirits, we recommend that you clean the surface with a 50:50 mix of denatured alcohol and water before applying the water-based product. 

GF's recommendation: (there are other great sanders in the market. These are the ones we are familiar with) Most pros own more than one sander as they are designed for different objectives.

SANDERS

1. Festool and Mirka systems are designed for the serious, high production professional.
   • Festool is a system not limited to just sanding equipment. All Festool tools hook up to the Festool's dust collection. For those of you in the Chicago area, JCLicht carries the full Festool line.
   • The Mirka is a great sanding system and is comparable to the Festool. Higher-end users report finding this system worth the cost.
2. Bosch offers the GET75-6N 6 In. Dual-Mode Random Orbit Sander with decent performance at a more palatable entry-level pricepoint and also makes a great dust collector.
3. SurfPrep will adapt to any dust collector. Surf Prep's foam sanding pads are now compatible to several models of sanders in other brands.

DUST COLLECTION

Any good shop vac will adapt to any sander that has a dust port connection. Rockler sells a great adaptor to connect your shop vac to any sander. Woodcraft offers Festool and sells many models of dust collection.

SANDPAPER AND OTHER ABRASIVES

• Check out the pricing on sandpaper for all sanders at Klingspors Woodworking Shop. Klingspor is an abrasive manufacturer that has options for multiple sanders. They have 9-hole paper that fits all Festool sander for half the price of most other places.
• All the Festool sanders are 9 holes on 5" sizes including the 5" Jetstream. The 6" models have 17 holes.
• Mirka makes Abranet which is a mesh abrasive pad that works on all types of sanders.

SIZE

• Most customers would find the 5" is suitable for furniture and cabinets. We use the big 6" Rotex on large flat surfaces like tabletops.
• Surf Prep excels at the specialty 3x4" rectangular shaped cabinet sander and their big 3 2/3" x 7" sanders for flat tabletops.

Finish sanding is the process of sanding between or before the final coats of topcoat. There are several options.

Be careful about just using numbers. For instance, the 220 grit sanding PAD is equivalent to 400 grit SANDPAPER. Sanding pads from different brands have similar names but different grits. Also a note on sanding pads - we like to abrade new ones a bit on raw wood and not use them straight out of the box. Used 220 sanding pads are perfect for that final sand before topcoat.

Another option for that final finish sand is synthetic steel wool. Most companies have the same color system: Green = coarse, Red = medium, Gray = fine, and white = super fine. For example:

• The Mirlon Gray Scuff Pad Total 1500 is equal to 1500 grit sandpaper or a very- well used 220 sanding pad.
• Mirlon's other scuff pad is Maroon with an equivalent of 360 grit and uses aluminum oxide as the bonded abrasive (2/0-3/0 Steel wool equivalent). The Grey Mirlon pads use Silicone Carbide as the bonded abrasive (4/0 or finer steel wool equivalent). So nice as you just don't debris from the pad.

Yes. Cedar naturally contains oil, which prevents a finish from polymerizing (cross-linking or attaching together), slowing down the dry time.

Wiping with mineral spirits prior to application will help. Increase dry times as well. Regarding prep-sanding Cedar for a finish, sand to 180-220 because it is extremely soft wood.