The idea for this article on urethanes came from an individual I talked with at a home show in Victorville, California. I was thinking of doing a column on urethanes but this gentleman brought it to front and center. He was having trouble getting a urethane finish to last on his front door. I thought the column would be an easy one to research and write. Heck, how complicated can urethanes be? Well, I'll tell you what, I REALLY opened up a can of worms with this column!

Complex Chemistry

The paint, excuse me, I mean "coatings", industry is very complicated. Paints and clear coatings are a witch's brew of many different ingredients and chemicals. They are blended in various amounts to create different properties. The terminology can get so technical so fast it can make your head swim. My advice to homeowners and professionals alike is to stay away from the chemistry aspect of coatings and concentrate entirely on the labeling and instructions about each product. If you carefully read a product label, you often will find clues as to how the product will perform. Isn't that convenient! Who would have thought it was that simple!

For example, just about every urethane label I have read has a paragraph heading "RECOMMENDED USE". It is vitally important that you read this paragraph before you buy the product! Don't buy a urethane designed for floors to put on your exterior door. There are big chemical differences in the products.

Urethane vs. Varnish?

Old fashioned varnishes are not much different than today's urethanes. The major difference is purely chemical. Urethanes contain an isocyanate (what the heck is that?). Evidently an isocyanate is a chemical chain that contains nitrogen, carbon, and oxygen. When combined with a polyol like traditional linseed oil, you get a urethane!

Urethanes outperform traditional varnishes because they resist chemicals, scuffs, and scratches. For the most part, urethanes are also slower to yellow or amber.

Sunscreens for Wood

Ultraviolet (UV) light has garnered lots of publicity in the past 5 - 10 years. We have finally figured out that it destroys just about everything -our skin, vinyl siding, certain plastics, colors, fabrics, wood, coatings, etc. The UV rays are invisible but evidently have the same impact as those very cool phaser pistols you see in "Star Wars" movies and such. UV radiation blasts things apart on a microscopic level.

Adding pigments or colors to urethane will help them to significantly resist UV degradation. What, you didn't know you can add pigments to urethanes? You bet you can! In reality, urethanes or varnishes are nothing more than clear paint. In fact, if you are trying to match stained woods, it can be done by blending pigments into a urethane. I have done it on several jobs to match new woodwork with older stained wood. The look is dramatic. After you achieve the perfect color, you then apply two coats of clear urethane over the pigmented coating. Without this protection pigments might wipe off when cleaning or brushed against with a white article of clothing.

Doors vs. Floors

Wood exposed to the elements and weather turns into a living, breathing "creature". In other words it moves. Urethanes formulated for these applications have to be softer or more flexible than a urethane applied to a gymnasium floor. A wood door or exterior sign expands and contracts. If the urethane can't absorb this shock, it will simply pop off the wood.

Maybe your exterior door urethane failed because you put a floor urethane on the door? It could have also failed because it had too little UV protectors. The UV light could have destroyed the surface wood cells. These cells succumbed to gravity and took the urethane with it!

Water & Oil Don't Mix, or do...

Great strides have been made in coatings technology with respect to urethanes. Water "based" finishes are now available. However, it gets confusing from here on. Why? Because there are two main groups of water based clear finishes. The same is true for oil based as well. The best performing water based urethanes tend to be those that "crosslink". However, guess what? It will be tough, if not impossible for you to find these in your regular paint store or home center big box store. Sorry.......

Crosslinking - What is That?

When you apply a regular water based paint finish, the water begins to dry. The pigment and resin (glue) particles are pulled closer together. Eventually these particles are touching one another very tightly as the last little bit of water evaporates. The particles stick to one another and the surface which was painted. Each particle maintains its own personality, however, as it sticks to the particle next to it. There is no chemical crosslinking in this scenario.

Old fashioned linseed oil, many oil based urethanes, and some water based urethanes, however, chemically react as they dry or "cure". What really happens is that the urethane actually turns into one GIANT molecule of urethane. The individual particles crosslink and become one. As you might imagine, this type of finish is much more resistant to moisture infiltration and chemical attack.

You will never see anything on a urethane label about crosslinking. It is too technical. However, you will see mentions on the label about "non-yellowing" properties. Many people don't like a urethane to amber or yellow. If you want this property, you are going to pay for it in performance. The urethanes that do not yellow are NOT crosslinkers.....that's not something to be proud about if you are a urethane.

Hardness of Floor Finishes

Urethanes used on floors need to be very hard. Hardness is directly related to the amount or degree of crosslinking in a urethane. The more crosslinking, the harder the finish. Other ingredients(the oils or resins used)also influence hardness as well. Suffice it to say that price will often be a clue as to performance. The urethanes that contain more crosslinking capabilities or chemicals almost always contain more higher priced ingredients. This means more cost to us, the end user. Check the labels to see if this isn't true! Look to see what type of performance claims the manufacturer makes on the label. Read closely and you might just be surprised.

Bottom Line:

Do you want a high performance urethane? If so, stick with an oil based one. They resist chemicals better, usually have a higher gloss, they do not raise wood grain, and are almost always more durable than water based urethanes. If you want the ease of rinsing your brush in water or want a non-yellowing film, you will not get long term performance. The choice is yours to make.

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Urethane Manufacturers / Types

Every paint (coatings) company has a urethane/varnish line. I would need a 10 page bulletin to list the different brand names of each manufacturer. As discussed in other articles, the properties of many of the urethanes are similar when comparing ones used for SPECIFIC purposes. In other words, as long as you use the right urethane for the right thing, you should do fine. I have listed a few companies that I know to make great urethanes. That is NOT to say that companies that are not listed make inferior or lower quality products. Remember, use price as a roadmap. Low cost urethanes may give you sub-standard performance!

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Urethane Application Tips

Read the Label Instructions!!!! Carefully!!

The first thing you are going to notice, especially if you choose to use a water based urethane, is that there are many things you can't do when you use a water urethane. For example, maybe you have had great success in the past sanding with steel wool. Those days are gone. Why? Because you leave very small pieces behind which will rust when you apply the urethane!

You may also find out that a previously applied finish has to be completely removed. This can be a bummer! Read the label application instructions carefully.

Surface Preparation is Everything

Your finial finish will be only a few thousandths of an inch thick when dry. Small imperfections will show through the finish. High gloss products magnify surface defects such as sanding imperfections, sanding scratches, bumps, hammer marks, etc. If you want a surface like glass, you must get it to a glass like finish before the finish is applied.

A water based urethane will absolutely raise the grain slightly. This is not a problem. Let the finish dry as recommended on the label. Then sand the finish lightly to knock off these high spots. When the second coat is applied, you should not have any grain problems whatsoever.

Clean, dry, dust-free surfaces are a must. Do not underestimate the importance of this. Remember, the urethane "sticks" to whatever is at the surface of the wood. If it is wax, dirt, dust, etc., don't be surprised when the urethane peels off in large sheets. I know this from experience. I urethaned the beautiful floors in a house once. Too bad I didn't remove the wax that the previous owner had applied!

Stir - Don't Shake

I always have to watch myself around urethanes. As soon as I pick up a can I want to shake it as I do with paint. Shaking urethanes introduces tiny bubbles within the product. Sometimes these bubbles will not disperse before the finish dries. If this happens you have big problems!

Sand Between Coats - Time Applications!

To get a mirror like finish you must lightly sand between coats. To get maximum adhesion between coats, it is important to apply the second, third, etc. coats as soon as the manufacturer says it is permissible. Why? Because often the previously applied coat will chemically and mechanically bond to the following coat. This can really make for a durable finish. Don't let days or weeks pass between coats.

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Paint Removal -  Tips and Techniques

Choose the Right Product

Paint removers are not all created equal. Grab the wrong product from the shelf and you can easily get poor performance. Take 10 - 15 minutes while at the store to READ THE LABEL. Note what surfaces it will harm. Pay attention to the consistency of the finish removal solvent. If you are working on a vertical surface or a ceiling, the stripper better be a paste or a very thick gel.

Do Finish Removal Chemicals Leave Behind Harmful By-Products?

Not really. The active chemical ingredients may cause you the user to get sick if you inhaled the fumes for hours on end. However, once the paint or clear finished is removed and you wipe the surface with clear mineral spirits, you will be OK. This is true even if you are stripping baby furniture!

Required Materials to do Stripping Work

You will need rubber gloves, eye goggles, plastic sheeting to protect floors and surrounding objects, paper towels, a plastic or steel container to place stripped paint in, toothpicks for fine detail work, a stripping pad, plenty of steel wool, different scraping tools and regular tools to remove hardware.

Getting Ready to Strip

Paint that is transformed back into a liquid state by stripper will stick again to a surface. For this reason you must put down drop cloths to protect objects from the gooey paint. Newspapers or cardboard will work fine in small areas. Work in a well ventilated area but do not place a fan near where you are working. Wind will cause the strippers to dry prematurely. Excessive heat will also decrease the performance of strippers. You will get great results working in temperatures between 60 and 80 degrees F.

Stripper Application

This is a critical aspect of the job. You absolutely must follow the directions on the can. Each product is different! For example, some thick gel strippers must NOT be brushed on like paint. You can only brush in one direction. Read the label and pay attention.

Sit Back and Relax

The biggest mistake people make with strippers is removing them too early. A stripper will develop a protective skin or sometimes appear dried out. In many instances it is still working. You need to leave it alone and once again follow the instructions for dwell time - the time the paint removers must sit and work.

Scraping and Rinsing

Plastic scraping tools work best. Hard metal scrapers can gouge wood softened by the stripper. Use toothpicks or large hardwood splinters to remove paint from grooves. A stripping pad dipped in mineral spirits will remove the fine paint film after you have scraped away the heavy deposits. Steel wool should only be used on varnish only.

Author's Note: We've received other questions about similar problems. Here's one from Leigh, in Columbus, OH.

"I have a cement pad/stoop located in front of my front door. The previous owners painted this a dark brown. The paint is chipping off. I was wondering if you could please tell me how to remove this paint? The pad is in good condition, and I would much rather prefer a 'natural' cement color! Thank you! "

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Paint Removers - Performance Guidelines

There are many companies that make paint removers. However, there are just a few leaders in the field. Some paint removal manufacturers make products for commercial and industrial applications. I have hunted for the ones that make products for you and me - i.e. homeowners. Many of the products below can be found at local hardware stores, large home centers, and paint stores.

As you will see from the guidelines below, you have to be very careful about selecting the right paint or finish solvent. There is no one miracle paint stripper that is universally safe on all surfaces! Take your time and make sure that you pick the right one. For example, let's say that you intend to strip paint from some delicate aluminum object or thin aluminum siding. If you purchase an alkaline stripper you have got problems! The stripper will eat away and etch the aluminum! Read the labels, especially the area of the label that speaks to Precautions!

Several of the companies below have very handy pamphlets and charts that help you select the correct stripper. Klean-Strip is one in particular. Their chart lists properties such as strength, thickness, speed, wet time, water washability, etc. I suggest you call all of the manufacturers and request their product literature. It will be well worth it!

Dumond Chemicals, Inc.

Dumond Chemical makes the Peel Away product. This is the paste like remover that requires a special paper so that you can remove up to 30 layers of paint in one application! They make 4 primary products:

• Peel Away 6
  This safe remover is specially designed for fine furniture restoration. It will remove urethanes and varnish without harming or discoloring wood. In addition, it can remove many layers of latex paints and varnish from virtually any surface.

• Peel Away 7
  This tough remover will attack and remove tough coatings such as oil paints, epoxies, urethanes, traffic paint, chlorinated rubber, automotive paints, etc. It is safe on many substrates including hardwoods and aluminum.
• Peel Away 21
  This stripper is safe for virtually any surface and will remove many household paints.

Klean-Strip

Klean Strip makes a wide range of residential strippers. You name it, and they have it. They have many different stripping products. They range from furniture stain removers to adhesive/mastic removers.

• Premium Stripper
  This is a stripper for latex and oil based paints, urethanes, epoxy varnish, varnish, shellac and lacquer. It comes three ways: #1 KS-3 Thick Brushable Paste for tough jobs. #2 Easy Sprayable is a thin bodied stripper that is water washable. Be careful as the water rinse can raise wood grain. #3. Convenient Aerosol stripper is great for small projects.

• Heavy Bodied Paint Remover
  This product is a moderately thick stripper that cuts through multiple layers of old finish. It is water washable. It is great for painted metal.
• Strip-X Stripper
  Removes paint, varnish and stain. Water washable and clings to vertical surfaces.
• Klean-Kutter Remover
  A thin liquid remover made to remove clear finishes. Great for antiques.
• Deep Down Stain Stripper
  This product helps you remove stains from wood. Penetrates virtually all clear finishes. Sold in a spray can.
• Fiberglass Stripper
  Use this to remove paint from fiberglass. Water washable.
• Adhesive Remover
  A heavy-duty paste for removing old floor covering adhesives, mastic, contact cement, asphalt and latex adhesives.
• Citristrip
  A stripping gel that contains no methylene chloride. A great orange scent allows you to work comfortably indoors.
• Gillespie Furniture Stripper
  Removes multiple layers of paint from wood furniture in a flash!

Parks Corporation

Parks makes a full line of paint and clear finish removers. they also make a paint deglosser for increasing adhesion if you are going to repaint over glossy paints. Call them for sure and ask for this brochure by title: The Facts About Finish Removal.

• Pro Stripper II
  This removes oil, latex and clear finishes safely.

• Pro Stripper
  Fast acting methylene chloride. A semi-paste.
• No Drip Strip
  Semi-paste. Clings well to vertical surfaces.
• Liquid Strip
  Liquid formula great for detailed furniture restoration work.
• Furniture Refinisher
  Removes old furniture finishes and dirt. No need to sand or scrape. Simply recoat with new clear finish.
• Adhesive Remover
  Removes hardened adhesives beneath floor tile, ceramic tile, paneling, etc.
• Wipe - It - Off
  Removes dried latex paint spills or spatters without affecting underlying oil based or urethane surfaces. Great for clean up after painting those bedroom walls without making sure the drop cloth was close enough to the wall!

Author's Note: We've received other questions about similar problems. Here's one from Leigh, in Columbus, OH.

"I have a cement pad/stoop located in front of my front door. The previous owners painted this a dark brown. The paint is chipping off. I was wondering if you could please tell me how to remove this paint? The pad is in good condition, and I would much rather prefer a 'natural' cement color! Thank you! "

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When Kathy (my lovely wife) and I were dating, one of our hobbies was to purchase and refinish antiques. The antique market was really beginning to boom in the early 1970's. We still have many of the objects we purchased. Often the pieces of furniture needed help. I don't know how many gallons of paint stripper we used, but is was significant! It used to drive my Dad crazy, as sometimes in the colder months we would strip furniture in the basement of my house. The methylene chloride fumes would permeate the entire house.

Two years after we were married, Kathy and I purchased our second home. It had a gorgeous solid oak handrail, spindles and intricately carved newel post. We spent 5 days and nights restoring it to its original beauty. I believe we caused a shortage of paper towels and toothpicks in Cincinnati during this time period! Needless to say, we both became fairly proficient at applying paint stripper and removing clear finishes and multiple layers of paint. I only wish that some of the products made today would have been available to us 25 years ago!

30 Layers of Paint at Once....?

Not on my best day could I ever have removed 30 layers of paint in one application. Today you can purchase a high powered stripper (Peel Away I) that will do just that. The stripper is a thick trowelable paste that aggressively attacks layer after layer of paint. It is especially suitable for safely removing lead paint. By softening the old paint film it creates no hazardous lead dust. Virtually every old house contains lead paint. It can cause serious health problems. Just ask my neighbors who almost lost their dog to lead poisoning. The dog chewed on some woodwork in the basement that was covered with lead based paint.

Safe Strippers

The old strippers Kathy and I used contained volatile toxic chemicals such as methylene chloride. These old strippers were very fast acting. In the interest of public safety and limiting corporate liability, stripper companies developed "safe" strippers that use non-volatile organic compounds to soften paint films. The tradeoff for safety is speed of removal. The new strippers now take hours to do their jobs. It is a worthwhile tradeoff. Old strippers could soften a paint film in 5 - 10 minutes. It is not uncommon for the newer safe strippers to take hours to perform their magic.

Performance

Consumer Reports published test results in their June 1992 issue. They tested some of the new safe strippers. The report states that they felt that the Peel Away product "..was the fastest, easiest to use, and most effective." I highly recommend that you go to your local library and check out this simple report. It may help you make a decision when deciding which stripper to purchase.

It is important to realize that performance of strippers is dependent upon making sure you match the right product to the paint. This is not always easy! I don't know about you, but I find it virtually impossible to distinguish a latex paint from an oil based paint once they have been on a surface for 10 or more years.

The older methylene chloride strippers (which you can still purchase!) can remove 4 to 5 layers of oil based paint in a single application. However they usually don't do nearly as well on latex paints. Some of the safer strippers do the exact opposite! They work great on latex paint but do poorly on oil paints.

The point is this: If your stripper performs poorly it may not be a bad product! You may have to switch products or types of stripper. In addition, the paint film may consist of different types of paint. You may have 4 layers of latex paint on top of 5 layers of oil paint. It is not uncommon. This may require you to switch stripper during the middle of the job.

Harming the Substrate

Some of the newer "safe" strippers are very caustic. They have a very high pH and as such can actually degrade, corrode or pit metals like aluminum or magnesium. Some of these same strippers can discolor beautiful hardwoods like the oak handrail Kathy and I stripped.

You must be very cautious when purchasing the strippers. Read all of the Precautionary Warnings on the label before you purchase or use the products. There are strippers that will safely and effectively remove any finish (paint, varnish, urethane, lacquer, epoxy paint, chlorinated rubber, traffic paint, paint from masonry, etc.). You just have to take your time and match the stripper to the correct finish AND substrate!

Protect yourself as well. Strippers can really burn your skin and eyes. Wear rubber gloves and eye goggles when working with these products. Do not work in confined poorly ventilated spaces. If you do, your Dad may come and get you like he did me!

Author's Note: We've received other questions about similar problems. Here's one from Leigh, in Columbus, OH.

"I have a cement pad/stoop located in front of my front door. The previous owners painted this a dark brown. The paint is chipping off. I was wondering if you could please tell me how to remove this paint? The pad is in good condition, and I would much rather prefer a 'natural' cement color! Thank you! "

Click here to read about an interesting tip for storing leftover paint.

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