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Heat Lock Guide

 

Required Items:
- Veneer
- Heat Lock™ Adhesive
- Glue Roller

Optional Items:
- Masking Tape
- Scissors
- Veneer Saw
- Veneer Softener

Iron-On Veneering With BetterBond Heat LockT

Heat Lock BrochureFor small or curved projects, Heat Lock™ is a superb adhesive that takes only a small amount of practice to master. It is highly recommended that you experiment with veneer scraps before tackling your first project.

Some veneers do have a tendency to split under heat. The rapid shrinkage causes the wood fibers to weaken and come apart. To minimize this, you can set the iron to put out some steam and be sure to use a cloth between the veneer and the iron.

Remember that any cracks or splits already existing in the veneer will get larger under heat so start with a section of the veneer that is free of any splits. Since the edges have a tendency to split, its always best to oversize the substrate and veneer. Then cut it down to size when the veneering part is done.

About Iron-On Wood Veneering
This technique for applying wood veneer has been around for awhile and there have been as many successes as there have been stories of disaster. For each failed panel I can always point out at least one of the following causes:

  • Lack of Adequate Heat - It is critical to allow plenty of time for the iron to reactivate the glue. Don't rush the process. Theoretically, the veneer should be hot enough that you wouldn't want to touch it.
     
  • Drying & Curing - Once applied, Heat Lock has to dry before the ironing process can begin. Drying typically takes less than 25 minutes. You can proceed with the ironing process as soon as the glue is dry but do not wait more than a few hours to complete your project. After a short while, the adhesive polymers begin "cross linking" which makes it difficult to reactivate the glue.
     
  • Using the Wrong Adhesive - It is easy to find websites and articles with claims that plain yellow glue can be used for iron-on veneering. This is partially correct. The problem with yellow glue is that it doesn't dry hard. Instead, it remains semi-flexible and this creates a problem known as veneer creep. Seasonal changes in humidity cause the wood cells in a veneer to expand and contract. If the glue is not strong enough to prevent the creeping action, the veneer will eventually bubble and delaminate. Essentially this means that many of the yellow glue success stories are really just temporary success stories.

Preparing The Substrate
Make sure the substrate (the area you want to veneer) is clean and lightly scuffed with 100 grit sandpaper. Heat Lock will work with a variety of substrate materials such as wood, plywood, MDF and particle board.

Applying Heat Lock™
If you are using a straight-grained wood, it's a good idea to "dry iron" the veneer before applying the adhesive. Set the iron to the medium-high setting and gently move the iron around the veneer until it is warm. This will pre-shrink the veneer to minimize any splitting.

Heat Lock can be applied with a paint brush, foam roller, or glue roller. Two coats of adhesive may need to be applied to the substrate if you use a paint brush or foam roller. However, a glue roller has the tendency to apply the adhesive a bit thicker (approx. 9/1000") and, therefore, is the ideal choice. Unlike contact cement, Heat Lock disperses no volatile organic compounds (VOC's) so it can be applied indoors.

Do not thin Heat Lock. It's formulated for optimum flow directly from the bottle.

Start with the substrate by applying a zigzag pattern of adhesive to the surface. Use the roller to spread it out evenly. Be sure to cover the entire surface. The key is to apply a uniform coat. If the veneer adhesive drips over the edges, it can be cleaned up (while wet) with a damp rag.

Next, apply the adhesive to the veneer in the same manner as the substrate. The best method is to cut the veneer slightly oversized and tape the edges down to a scrap board. This will prevent the glue from getting on the veneer face during application. If the adhesive does get on the face of the veneer, a clean finish will be difficult.

The surface of the substrate and veneer should appear evenly covered after drying. A second coat of adhesive is frequently necessary.

Clean Up
The uncured adhesive will clean up with warm water. Rinse off the roller or brush immediately after use. The adhesive begins drying quickly so do this now while the veneer and substrate are setting up.

An Ounce Of Prevention
A spritz of veneer softener on the surface will give the veneer some flexibility if it's very wavy, buckled, or high in moisture content. Some species such as maple, bubinga, and hickory have a tendency to split when excessive heat is applied. Veneer softener will greatly minimize this issue.

Bonding The Veneer
Wait for the glue to dry before proceeding with the clothes iron. It typically takes 20 to 30 minutes for the glue to fully dry. Once the glue has dried, do not delay the iron-on process. After 6 hours, the adhesive becomes increasingly difficult to reactivate.

Turn the clothes iron on and set it to medium/high with a small amount of steam. On some irons, this will be the "cotton" setting which is approximately 193°F. Allow a minute or two for the iron to heat up. Now is a good time to use scissors or a razor knife to trim off the edges where the veneer was taped over. This will prevent you from accidentally using the dry veneer surface on the substrate.

Place an old cotton or flannel shirt over the veneer face and begin ironing from the center and work toward the edges. Apply even downward pressure giving the full veneer area ample time to heat up, reactivate, and bond. Be sure to keep the iron moving at all times.

Allow an additional 1 to 3 hours for full bond strength.

Inspection
After the veneer has cooled off, check the surface for any areas that feel uneven. You can re-heat any areas that did not properly bond. These are areas where the glue was not fully heated.

Lastly, check the edges of the veneer for loosening. Moderate upward pressure with your fingernail should not lift the edges. If it does, re-heat the veneer and check it again.


If you're still unsure of the final bond, spritz the surface of the veneer with water. Allow the water to sit for 3 to 4 minutes. This will cause the veneer to swell and any poorly bonded will bubble-up. Just re-heat those areas and you're done!

Don't forget to turn off the clothes iron when you are finished!

Finishing The Veneered Panel
Lightly sand the veneer being careful to avoid sanding through the veneer itself. It can be tricky so do this by hand. It's best to let the adhesive fully harden before staining/finishing the veneered surface. Since Heat Lock cures hard, practically any stain or finish can be applied.

Check This Out
For tricky veneers that have a tendency to split under the heat of the iron, you want to try this alternative method.

  1. Apply the softener to the veneer and iron it to dry it. Let's call this "pre-softening".
  2. Apply the Heat Lock to the veneer and substrate and let it set up. Don't wait too long after it is dry to continue.
  3. Use the iron, with slightly less heat than previously used, to adhere the veneer to the substrate.
  4. When you are done, spritz the veneer face very lightly with softener. Let it sit with the softener on it until it dries on its own (no ironing).

Helpful Ideas
Bookmatching or any other veneer seaming technique can be very difficult with Heat Lock due to veneer shrinkage from the heat of the iron. However, there is a "work-around" for the problem.

To solve the shrinking problem, you can place a straight piece of clothes hanger wire about 2" away from the seam. Then iron down the seam. Next, pull the clothes hanger wire out and iron down the bubble that it left behind. This will force the seam tight. This technique requires a bit of practice but it does work well.

Still have questions?
The Heat Lock FAQ is available by clicking here.

 

 

Click on the Pictures
for Larger View

Apply Glue
Glue applied to substrate

Apply Heat Lock
Application of glue to veneer

Glue Drying
Glue drying on veneer

Trim the Veneer
Cut off the veneer edges

Iron the Veneer
Iron the veneer face

Check for Bond
Check for a good bond

Completed Bird Eye Maple Veneer Panel
Completed panel

 

 

 

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