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Any new tool that you use requires practice to master it.

Remember when you used a spray gun the first time.  The use of the liquid mask in a spray gun will require practice to reach the proper thickness (5-6 MILS wet).

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Do not use additives.

Do not use on stained glass, frosted glass, etched glass, textured glass, tinted glass, any coated glass, plastic glass or Plexiglas™.

Do not topcoat or cover with lacquers, primers or paints containing ketones or alchols.

Do not topcoat with alkyd or oil base paint unless thoroughly dry.


Do ask about the glass to make sure that it is plain glass with no coating.

Do test the glass if not sure.

Do check the glass for prior cuts or scraps so that you can point out these problem areas before you start the job.   Note on your contract where the damaged windows are and have the owner initial the contract at the portion of the contract dealing with the damage (cuts, scraps).

Do prime steel frames before coating with the liquid mask.


Leaving the liquid mask long enough to fully dry and cure is extremely important.  It is best to let the liquid mask dry over night before topcoating with paint. Put the mask on early in the job and do other parts of the job while the liquid mask dries.

If the mask is not fully dry when it is topcoated with paint, the moisture and other volatiles in the liquid mask may cause the topcoat or paint to crack.  This is especially true for alkyd or oil based paints used as the topcoat.  If the humidity is high, the liquid mask will take longer to dry and cure.  For example, if you are painting indoors and the wallboard seams have just been spackled, the humidity will remain high for over a day, and the liquid mask should be allowed to dry for over a day.


Alligatoring can be a problem if the liquid mask is topcoated before it dries.  It is very important to follow the instructions on the container to avoid this problem.  Alligatoring is caused by painting over the liquid mask before it is completely dry and cured.  Let the liquid mask dry overnight when possible.  If the humidity is high, such as before or after a rain or in the morning, let the liquid mask dry for several hours.  Error on the side of waiting too long. 


The liquid mask can be applied over an alkyd or oil based paint after normal preparation of the oil based paint surface for painting, such as sanding of rough spots, removal of dirt, etc..

An oil-based paint can be used to topcoat the liquid mask, but the mask must be completely dry before topcoating the liquid mask.  The same is true for latex paints.  You should test first under the conditions that will be experienced at the job.


The liquid mask can be sprayed using a conventional, an airless or a HVLP sprayer.  Below are some suggestions that may be of help.  However, testing / practicing is always recommended to make sure that you have the correct set-up.

A conventional sprayer should use the set-up recommended for a thick latex paint.

An airless sprayer should be operated at approximately 2,500 psi with a 411-513 tip.

A HVLP sprayer should use the set-up recommended for a thick latex paint.  Pressurize the cup or pot if possible. 


Spray on a light coat using a horizontal path across some of the panes and then spray the panes using a vertical path.

If running or sagging occurs, immediately smooth out the area with a brush.


The mask should be cut very carefully.  Glass is more tender than you think and can be easily cut or scraped.

Low humidity, hot and dry conditions or sunny days can cause the mask to be difficult to remove. The removal can be helped by wetting the mask with water on a sponge or cloth.  However, the easiest method is to remove the mask in the morning before the sun dries out the mask on the glass.

If the mask does not peel off in one piece, the mask is too thin.  A second coat of mask should be sprayed over the first coat to increase its thickness and strength. 

The more humid that the climate is; the thinner the mask can be.  Practice will show you what thickness is needed.  Usually, a thickness of 4-5 MILS when wet will do.