Thursday, February 27, 2020

High Temperature Masking Tapes for Baked and Powder Paint Finishes

One of the most popular ways to finish metals is to use paint. Traditional automotive paints and newer powder paints (powder coating) require baking to achieve the correct finished look. In this post I will be discussing the options that are available for each.

A big limiting factor is that automotive paints and silicone don't mix. Any contamination by silicone prevents the paint from drying correctly. This is a bummer because silicone adhesive is capable of withstanding much higher temperatures for longer periods of time than acrylic or rubber adhesives.

Because of this I can only recommend a high temperature crepe paper masking tape.  This is like regular masking tape except it has a much higher temperature range.  These tapes can generally withstand 325ºF (163ºC) to 350ºF (177ºC) for between 30 minutes and 1 hour.  You should always check the manufacturer's spec sheet to make sure of the parameters.  After the bake cycle these tapes will remove cleanly, generally in 1 piece. If you bake the tape at a lower temperature you can get a longer exposure to the heat.  If you drop down to 230ºF (110ºC) you can go from a bake cycle of 30 minutes to 1 hour. These tapes are generally used in roll form but die-cut shapes are available. Even if you aren't baking, I recommend using the high temperature masking tape because it will remove easily without leaving residue.

Another automotive tape that has high temperature application is fine line masking tape.  Fine line masking tape is much thinner in cross-section that standard masking tape so there is a smaller ridge of paint build up along the masking line.  These tapes are often used in pin striping and other detail work. They can usually go to 250ºF (120ºC) for up to 30 minutes.

Powder coating is a process where dry paint (powder paint) is sprayed onto the item to be painted.  The item is then placed in an oven and baked at temperatures up to 400०F (190ºC). The powder melts and flows together creating a durable, seamless finish. This requires the use of silicone adhesives that can withstand up to 500ºF (245ºC) for an hour or more.

There are two tapes that are used for the majority of masking in powder painting; polyimide
and polyester. The polyimide is a sort of bronze/brown color and the polyester is usually green. Both of these tape are available with silicone adhesive. The big difference between the two is that the polyimide backing can go up to 500०F (245ºC) while the polyester backing can only go up to 400ºF (190ºC).

Many parts that are powder coated have surfaces that need to remain free of paint for a variety of reasons.  In some instances you can use standard rolls of tape but many times the pieces need to be die-cut into a special shape. Thankfully this is easy to do.

The last type of tape for powder coating is self-fusing silicone tape.  It is used on tubes or rods where you are wrapping the tape completely around it. This tape has no adhesive on it so it can't leave residue.  To use it simply overlap it slightly and it will bond to itself.  To remove just cut it off.

If you have any questions or if you need samples of these tapes please feel free to get in touch at 1-800-882-7348 or

Happy Taping!!

Friday, February 14, 2020

Acrylic Foam Tapes

Just over 40 years ago 3M shocked the tape world (as they often do) with a new product group called VHB (Very High Bond) tapes.  These tapes featured a very dense foam core paired with ultra high performance acrylic adhesive that creates a very permanent bond on most non-porous surfaces.  The combination created tapes that offered unbelievable performance when used correctly. When these tapes first came out there were only a limited number of varieties for fairly straightforward applications.  Today there are dozens of different products for almost any application you can think of. Industries that use these types of tape include aerospace, automotive, appliances, signs, and displays.

These tapes have properties that make them superior to mechanical fasteners (rivets, screws, nuts and bolts, even welding).  Because the foam core of the tape expands and contracts with the ambient temperature they can eliminate stress fractures on exterior signage.  Their ability to absorb vibration makes them perfect for machinery and motor vehicle applications. Last but not least they are fast, clean and easy to use saving significant time and money over mechanical fasteners.

For many years (decades) 3M enjoyed a virtual monopoly on these type of tapes because no other company could make anything that had close to the same level of performance.  This lead to the two biggest issues with them: they were extremely expensive and they had limited distribution. Well all that has recently changed.

Today there is a competitor to the VHB line from the upstart company AFTC.  AFTC was started in Europe and today it is a global organization that offers acrylic foam tapes that offer the same or better performance than VHB products yet they are 35% to 50% less expensive. They are marketed under the Silver Tape brand and I can say that they do everything they promise.

The key to getting a permanent bond is to choose the right tape and then prepare the surface correctly. Then you have to apply it correctly to insure a perfect bond. If you do these things you will have great results and happy customers. Let's talk about the tapes first.

One of the most popular styles are the clear foams.  They aren't really foam but rather solid clear urethane that acts like a foam.  These tapes are perfect for acrylics and glass.  They work really well on metals and painted surfaces as well. Because they are clear they aren't as visible in the finished product.  They are very popular in signs and displays where seeing the tape would detract from the finished product.

There are also standard tapes that are white or light gray in color.  They are designed for use on metals (bare or painted), some plastics and painted or varnished wood.  They can also be used on brick and finished concrete with very good results. They are widely used where the use of mechanical fasteners is impractical from an installation or appearance standpoint. Recently a cold temperature version has been developed that can be applied at temps as low as 30 degrees Fahrenheit.

Another newcomer is tape designed to stick to powder coated metals.  Powder coating has become very popular in recent years because it produces a very durable finish.  The downside is that you can't really bond to it effectively because one of the components of the powder is wax.  The wax allows the powder to flow together when it melts and create that durable finish.  This same tape can also be used on low surface energy plastics like polypropylene and ABS.

Next is proper surface preparation.  These tapes can be extremely finicky and they won't give you maximum performance if you skip this.  The key to success is to make sure the surface is clean and dry.  If you use a standard cleaner like Fantastik or Formula 409 you should get a nice clean surface.  Some surface require a little more than this. If you are sticking to glass you should use a silane treatment to prepare the glass for adhesive.  The silane treatment fills in any imperfections in the surface of the glass.  Here is a link to a 3M technical bulletin on the subject:

Another surface that needs prep is aluminum.  When aluminum is extruded into bars or angles it is covered with a lubricant to help the process.  This lubricant can get into the surface imperfections of the aluminum and it will prevent a strong bond.  It is recommended that in addition to cleaning you should use an abrasive pad (Scotch Brite or similar) to rough up the surface to help get a clean surface. Do this before you use the cleaner.

I also want to talk about acrylic sheet.  One of the components that go into making acrylic sheet is acrylic oil.  If the acrylic isn't cured correctly there could be significant amounts of acrylic oil left in the acrylic.  You can tell if this is the case by touching the acrylic.  If it feel greasy then you have a problem.  It will be very difficult to achieve a strong bond.

Finally comes the actual application of the tape.  One of the worst things you can do is touch the adhesive with your fingers.  The oil in your skin will contaminate the adhesive and reduce the ultimate bond strength.  It could cause the tape to fail in the field.  Handle the tape by the edges of the roll.  If you do have to touch the adhesive to start the roll try not to use the end where you touched it.  Cut it off and throw it away. Once the tape is applied rub it down with a squeegee or roller to obtain maximum contact of the adhesive.

One of the interesting properties of these tapes is that the adhesive bond gets stronger over the course of 72 hours (3 days).  If you can, try to avoid maximum stress on the tape for that period.

If you have questions regarding the use of acrylic foam tapes please feel free to get in touch at or give us a call at 1-800-882-7348.

Happy Taping!!!