There are numerous reasons why you would choose to mask the product prior to laser engraving, and some of these would include the following:

• Color fill or paint filling is required after laser engraving
• Protecting the piece from scratches, handling, smoke/residue damage
• Sandblasting is required
• Determining the location of laser-engraved graphics

Color Filling Or Paint Filling

This is the most common reason for applying a mask prior to laser engraving. Typically, paint is sprayed or applied to the areas where the laser engraving has occurred. Many laser technicians use household spray balms which are available in numerous colors from your local hardware store. In our shop, we always have a solid inventory of gold, silver, white, red, blue and black spray balms.

Here is a small tip: If you plan on paint filling or color filling glass or acrylic, make sure you do not engrave on the reverse face. Because you will be viewing it from the front face, your eyes will have to look through the laser-marked graphics first, which are typically frosted, before they see the painted graphics. And hence, if you color fill on the reverse face, you can expect a dull and milky appearance to your color.

A main reason for using a mask is to allow paint application. Here we use a normal spray balm to apply some color to our laser-engraved plaque.

Removing the mask after laser cutting.

Protecting The Piece

As laser engravers, we strive to take care of all items we engrave, but the normal day to day handling of items can lead to unwanted scratches and marks. It can be hard to protect that beautiful (and expensive) piece of glass. To protect from those unwanted marks and scratches, we will mask even if additional sandblasting or color filling is not required. Even after we have engraved and finished with the product, applying a light mask to the face provides additional protection.

Applying a mask can also serve to protect the item from smoke and residue damage, which is often the result of laser engraving.

Sandblasting Is Required

Glass products will often require sandblasting to provide that professional look, appearance and depth. There is nothing like a piece of glass which has been elegantly sandblasted. There are two main techniques for preparing an item for sandblasting. The traditional method involves creating, preparing and then applying the mask onto the intended item. The other method is to laser engrave the graphics through the mask and then sandblast. Every engraver has their preference as to which method they utilize. The shape and size of the item may lend itself better to one method over another.

In some cases, it is quicker to laser engrave the masked item and then complete the sandblasting stage instead of prepping, creating, and mounting the photo-resist mask. Of course, this will depend on your personal preferences.

Determining The Location

Even with the use of the red diodes which show where the engraved graphics will be positioned, you still may want to know for certain the location and appearance of your graphics. Here you can apply a low-adhesive paper mask and apply dark paint or boot polish. Then you just laser engrave the blackened paper mask with a very low-power setting to show your graphics. You are essentially using this low-power setting to remove the ink and to illustrate the graphics.

Now I would like to discuss the products and techniques for masking products. There are several types of products available to the laser technician to use.

Paper Mask

This paper product, which contains a very light adhesive, is known as premask or transfer tape. It is readily available from any sign supply company. The advantages of this product are that it is inexpensive, easy to apply, and easy to clean off. In addition, when color filling or paint filling, it can handle a fair amount of paint without the risk of paint seeping through. Some people even use it as a very light sandblast mask, but you have to be very careful as it does not take much to blast off the mask.

When doing really detailed and small graphics, this product can create some challenges. For tiny letters, it can be a bit difficult; occasionally, you have to laser engrave over the item for a second pass. Make sure you test before using transfer tape and attempting to laser engrave very small graphics.

Vinyl Mask

First, you need to be aware that the majority of vinyls contain PVC, which can actually damage your laser optics when engraving. Second, if you choose to ignore this warning, your ventilation system better be operating properly. Now that I have mentioned that, vinyl mask does have some great advantages. The biggest advantage is that this cost-effective mask applies easily, and it has a very aggressive adhesive, allowing for it to be used as a sandblast mask. The biggest disadvantage of this product is the same as its advantages‚ the aggressive adhesive. Removing the mask can be somewhat of a challenge. If you are not color or paint filling the item, simply soak the item in warm water for a few minutes to help release the adhesive.

In addition, there are thick vinyl masks which can be used for deep etching. Using this type of product would involve vector cutting the graphics. If you are after real fine graphics, using a thick vinyl mask will certainly not work. In fact, I would discourage you using this thick vinyl mask for letter heights which are smaller than 3/4" tall.

Dish Soap

Yes, I said soap! While we have not used this technique for some time, in its day, it was very effective. In the past, we would smear a drop or two of household dish soap on acrylic or glass over the intended engraved area. This offered great protection from smoke and residue damage. One real advantage of using dish soap is that you just rinse off the product with warm water to clean after laser engraving. Who knows, maybe you will even have soft skin after this!

LiquaMask

"Brush on.... peel off", is how this product is advertised. This laser-safe product creates a durable mask on wood, plastic, acrylic, glass, marble, leather, painted metal and other materials. By rolling or brushing this liquid mask, you can now protect even non-coated products. Because this product was just released earlier this year, I have not had much experience with the product. Our initial tests resulted in a few general comments. First, the product takes about an hour to air dry. Second, removal was a bit trickier than I thought. I can see this product being very well suited for non-coated products, which the paper and vinyl masks do not tend to work well on. That being said, I think a more in-depth test will result in more favourable results. Keep an eye on an upcoming article, as I plan on putting this product through some more intense tests.

A main reason for using a mask is to allow paint application. Here we use a normal spray balm to apply some color to our laser-engraved plaque.

Removing the mask after laser cutting.

Once the laser-engraving and color-filling steps are completed, removal of the mask is the next step.

By using a mask, smoke damage is minimized.

In summary, to mask or not to mask is the question. By looking at the different techniques and products which are available for the laser technician, you can decide how to properly answer this question.