I am having problems with veneering my cabinet gables. I build the box from 5/8 melamine, then roll contact cement on the gable and the paper backed veneer that has been finished with lacquer. I don't have a spray system. I use a handheld J-roller to press. It looks great for a while, then some bubbling occurs (this may take a week or a year). A hot iron over cloth does not flatten the bubble. I've had this happen with water base and solvent base. Anyone else use this method?
Did you rough up the melamine prior to gluing to give the glue some tooth? Was your contact application 100% and fairly even? Was the contact completely dry prior to lamination?
It sounds like a de-lam but could be from gassing of either the unreleased H2O or solvent or possibly the MDF-based melamine.
Following their instructions I've not had any failures and some of these have been in the field for at least 10 years. Lacquer caused no problems.
With melamine, a sand-over to break the shine does the trick. You will need to remove the melamine dust from the surface with a damp cloth. Get all the dust or the bond will probably fail from that.
As far as unbalanced panels are concerned, the veneer has no tensile properties across the grain in such a thin sheet. Along the length of the grain there is miniscule expansion and contraction - not enough to break a good bond. The paper backer is homogeneous and shouldn't cause a bond loss.
Yes, cold pressed adhesives will make an outstanding bond. So will the contact cement if the instructions are followed. Oh, and forget about vacuum bags for contact cement in this application. You will get only about 15 lbs./sq. inch of pressure. With a scraper you can get several hundred pounds/sq. inch.
This method is specifically for paper-backed veneers - species doesn't matter since the paper/veneer bond was accomplished by the manufacturer.
I only use paper-backed veneers and then only to deal with a special situation such as covering melamine cabinet ends.
A vacuum bag can't provide enough pressure per square inch to bond contact cement - less than 15 lbs. Use vacuum bags for adhesives that cure and form a rigid glue-line.
I have used your method and I would not recommend it. I have heard that water base is better for wood. But I would recommend the phenolic backed product.
I'm currently in the process of re-veneering a bunch of maple Nbl that was applied with the method you describe. I should also say that Formwood is replacing the veneer at no charge (good company) with a phenolic-backed product they have.
But in the future where possible I'm going to go with the vacuum method. I have not heard of a failure with this method and continue to hear of and experience failures with contact cement.
If you're going to use a glue that cures while under vacuum bag pressure, that will work.
Contact cement fails if not enough is applied to surfaces, surface(s) are dusty or contaminated, it has dried too long, it hasn't dried enough or not enough pressure is applied to create a full bond.
Fastbond 30 has been dependable for me - it has a much higher solids content than the solvent carried cements.
2. *Too much glue* and because of this your thinner base hasn't had near adequate time to evaporate.
3. "Lacquer thinner" (glue) base eeked through the veneer kraft backing, through the veneer and got to your finish causing it to bubble-up (gassing).