Questions about veneering

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I have been reading up on veneering in anticipation of my first project and I have gotten many conflicting stories.

First off many DIY speaker builders use either yellow glue and an iron, or contact cement, but the woodworkers guides all frown on both of these methods.

Many suggest cold press glues but I do not have a vacuum press or a clamping system as elaborate as what they recommend.

Also I want to veneer the cabinet AFTER it is built so a vacuum press seems to be out of the question.

There is the method of hide glue which there seems to be less detailed instruction on, how much pressure does this need and is it the best option? Where do you get hide glue?

Any help with these questions is greatly appreciated.

Sam
 
As a cabinetmaker for many years (more than I like to admit), I can tell you firsthand that every cabinet shop I've ever seen used contact cement. The main difference is that we spray it on.

I have also done the yellow glue/ iron method for years on some projects and can also vouch for it's effectiveness and ease.

Here's a step by step I wrote up after answering the first hundred questions about the procedure. :)

As an alternative to contact cement, try ironing on with yellow glue.
1. Prep substrate (should be perfectly flat and clean).
2. Cut veneer 1/2"-1" oversize.
3. With a foam roller cover, apply coat of yellow glue mixed with a little water (to let it roll on easier) to the substrate (I usually just pour a little glue on the suface and roll it around)
4. Roll on a coat to back of veneer using push-pins or tape to hold it down flat. Make sure no glue gets on face of veneer!
5. Substrate may need second coat, especially edges. You want the material to be built up on the
surface.
6. Let dry.
7. Position veneer on substrate (it will not adhere without heat).
8. Using household iron set at high, proceed to iron on the veneer, starting at center and working out. Keep the iron moving slowly so as not to burn the veneer. (trial piece good idea to get the feel for it). Use edge of wood block to keep pressure on it as you iron.
9. Trim as usual.
10. Before glueing adjacent sides, apply masking tape to the edge of the veneered side where it
meets the raw face that will be getting glue next. Again, make sure no glue gets on the face of any of the veneer!!! (this applies to using contact cement also)

A couple of big advantages are:
Bond strength.
Ability to position veneer.
Surface will be FLAT when you're done. Contact cement is much more difficult to control, and really isn't recommended for unbacked veneer.

Pete
 
yellow glue is PVA glue. the reason I prefer the contact cements is that they don't cause the fiber to expand, but I will defer to Peter with his professional experience.

Below is a veneer saw and a veneer roller which I bought from Constantines when they were in the Bronx.
 

Attachments

  • saw.jpg
    saw.jpg
    36.8 KB · Views: 1,588
I'm in the middle of a complex veneering job using unbacked veneer. I can vouch for Pete's thorough description of the process, to which i will add the following:

1. Titebond (yellow glue) works well.

2. Pick up a ShurLine 3 inch trim roller (sold at Home Despot). Works very well with the titebond (no thinning necessary).

3. Consider using a veneer softener with glue content if you are using unbacked, figured veneers. The softener helps reduce cracking of brittle veneer and the glue content sizes porous wood to prevent bleed-through.

4. Exacto knives work great for trimming. Change the blade often.

5. Use care and common sense when veneering over large driver cutouts on the front baffle. You want to avoid working around the hole only to find a big bump in the veneer once you reach the other side. I made this mistake once (ouch).
 
they don't cause the fiber to expand

But the veneer is so thin, it won't react on the substrate like solid wood. Once it's glued down, it doesn't have enough internal stress or strength to affect the work.

The worst part of this process is keeping the veneer flat while applying glue. I should have updated it to include:

2a) You can apply the glue to an entire sheet of veneer, let dry and then cut to size.

Pete
 
I think applying the veneer before doing the cutouts would be easier in general, but you would have to be very careful in doing the cutouts not to mar the surface.

A couple of more things my recent experiences have taught me.

1. Always put two coats of glue on the substrate. It's difficult to ensure complete coverage in a single pass. I found that very (VERY!) light sanding with 220 grit after the base coat gives a nice smooth surface for the second coat.

2. Applying glue to the back of the veneer is the best way to do iron on, but not if you are veneering large surfaces. Veneer will tend to wrinkle with the added moisture of the glue. Ironing small pieces flat shouldn't be a problem, but it can be real challenging with large surfaces.

For large surfaces, I apply three coats of glue to the substrate and only apply glue to the outer edges of the veneer (allowing for the overhang). You want the edges to be real tight if you want your handywork to become a family heirloom.

You will have the linger with the iron a bit longer, but it will work.
 
Guss asked:
could you refer me to a good place where I could buy some mahogany veneer online ?

The classic veneer shop is Constantines. They have been in business since God knows when and have been know for high quality stuff. The old man closed down the shop in Brooklyn years ago but I understand his son carries on the tradition from a shop in Florida.


http://www.constantines.com/

I have purchased some very nice raw veneers from an Ebay user named "thouge", but I haven't seen her around much recently.
]
 
One more thought

On the subject ofglueing down veneer use a small paint roller to spread out the glue. Pour a small amount in the middle of the cabinet surface ( or veneer surface ) and spread it out in a thin even coat. Two thin coats are much better than one thick one. It may take longer but it will actually dry faster and ensure a more even coverage of the suface. Oh yeh coat one way and after it dries coat at 90 degrees to the first way. More even coverage and less possibility of creating glue lines.

Mark

Cabinetmaker untill the f@#$%king ex sold my shop!!!!
 
spreading glue...

When I use the iron on method of veneering I have a plastic glue spreader I like to use. I have a 3" wide plastic putty knife that I cut 3/16" deep notches in, spaced 1/4" (roughly) apart. Made the spreader on my table saw. I push the glue around with that for a while, then I use a plain chip brush to even it out. I have to work fairly quickly but the process works well.

If the veneer wrinkles a bit I mist it down with water (non glue side) before I hit it with the iron. I only mist what I'm about to iron. I think the water helps get the heat to the glue too, because those sections seem to glue down faster.

I've also used some of the cold press glues without a vacuum press by waiting until they get very tacky, then putting the veneer down. I then use a veneer hammer to press the veneer down completely. I have seen some older panels bubble with this method, but those were on speakers that I did right after starting with this method so it could be a lack of practice.

I agree that getting contact cement on flat so that imperfections of the glue don't telegraph through is dificult at best. I wish I had the capability to spray it on well.

Scott
 
I have tried three ways, hide glue, yellow glue and contact cement.
I like contact cement the best. especialy for paperbacked.
Hide glue was recomended to me by a guy at woodcraft. It stinks, takes a long time to dry and doesn't work at all in humid weather.
 
Hi all,

I've just finished veneering some box floorstanding speakers.

Pete Mazz's iron/PVA glue recipe works very well. It has been over a week and there are no bubbles or warping of any kind.
Thanks Pete!

I followed Erik's advice and purchased the Shurline 3" trim roller. It's a touchup/paint roller but works ok for glue. Some of the fibres came off and stuck to the substrate but I could easily pick them out. This made rolling the glue on far easier and faster than a metal glue spreader that I previously used.

I used 2400 mm x 1200 mm x 0.6mm raw Tasmanian Myrtle (Australian) timber veneer. This is a large sheet but on closer inspection it is made of leaves approximately 1100mm long x 170mm wide. Since my speaker panels are wider than 170mm, each veneered sheet is actually 2 leaves.

I used cross-linking PVA glue, which claims to be stronger than normal PVA but the downside is that it sets faster (20min) so you have to work fast! I can also testify that MDF absorbs glue readily- 2 layers is a minimum.

Also I did not iron the veneer directly- instead I ironed over a cotton bedsheet. Any old cotton T-shirt or spare sheets should be fine- I highly recommend this to prevent your veneer from scorching. (my bedsheet was scorched at several spots, thus saving the veneer)

I didn't have sufficient clamps, so I used about 50kg of MDF panels. I followed the glue manufacturers instructions, and only clamped for 30mins, but waited for a few hours to dry before sanding and trimming.

However,

Within a few days of trimming and sanded the edges, I discovered that the veneer had shrunk. Not a lot, but at least ~1mm along my 222mm wide front baffle. Now the veneer does not fully extend to the edges of the MDF. The next time I try veneering I will wait at least a few days after glueing and shrinking before trimming and sanding excess veneer. I had no idea that veneer could shrink! Maybe this is due to the hot iron (expansion/contraction?), or maybe it was due to the glue?

Second, splits along veneer leaves (where the leaves had been book-matched and joined at the factory) developed. These run along the complete length of the veneer. The splits are about 1mm, and is probably due to the same shrinking problem described above. It may also be due to my ironing method- to remove the bubbles and flatten the curled veneer (glue to veneer causes it to curl) I ironed from the centreline towards the edges.

I wonder if this can be remedied by using masking tape to hold the leaves together? Actually I did this but took it off prior to claminping. What on earth was I thinking?
:( . Next time I will leave the tape on for a least a few days.

My only concern is that the glue on the masking take will stain the veneer during the ironing?

Has anyone tried veneering tape?
http://www.woodshopdemos.com/gclk-6.htm

No idea where to buy such a thing, but certainly it seems to be ideal since you leave it on permanently.
 
The split is a fraction of a millimetre, and not visible from a ~1m. However at close range it is clearly visible. In the photo below the shine in the midline is due to the reflection of the camera flash from the dried PVA glue, and shows the approximate width of the split.

Why would this split? And how would I prevent this in future?
 

Attachments

  • front baffle (closeup) #2.jpg
    front baffle (closeup) #2.jpg
    76.1 KB · Views: 854
Similar Result

I built a pair of speakers and veneered unbacked ash using contact cement. Thy both looked fine at first. I left one in the non-heated garage (in winter) and the other inside the house and left for a week around Christmas. Upon coming back, the one in the garage still looked fine, but the one in the house had split at seams, similar to your result. Once I brought the other speaker inside, it also split. I had left the veneer out for about a month prior to get used to the environment, but probably the change in humidity inside from Nov to Dec was significant. I plan to veneer during more constant humidity next time, if possible.

Sandy.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.