Home » Knowledge Base » Knowledge Base Article What's New  |  Site Map 

 

 
   
   
 
 


Today's
Sponsors:


Routech

RouterCAD

Royce Ayr Cutting Tools

RT Machine Co.

Safety Speed Cut

Sand-Rite Manufacturing

Sandman Products

Saw Trax Mfg.

Sawmill and Woodlot Magazine

Schmalz, Inc.

Schultz Forming Products

SCM Group USA, Inc.

SCM Group

SCM

SDN Contracting

Seagrave Coatings Corporation

Sears Trostel Lumber Co.

Shade Dri

Shomaker Lumber Company

ShopBot

SII Dry Kilns

Silvaris

Simantech

SIS Machinery

SK-USA

SketchList

SlipCon USA, Inc.

SnapDragon Associates, LLC

SNX Technologies

South State Machinery

South Texas Moulding

Southeast Tool, Inc.

Specialtytools.com

SprayGunWorld.com

NPO BARS

Nydree Flooring

Nyle Dry Kiln Systems

O'Shea Lumber Company

Old Mississippi Brick and Heart Pine Company

OMGA, Inc.

Omnitech Systems

Onsrud Cutter

Opti-Sand

Original Saw Company

Osolnik Machinery & Supplies

Patton Cabinet Doors

Paul Saws and Systems

People Logic Software Corp.

Pinske Edge

Pioneer Lumber Company

Planit Solutions Inc.

plastiMACH

Plogic Solutions Ltd.

Pond Cove Paint

Porter-Cable

Precision Drive Systems

Precision Saw Sharpeners

Premium Specialty Hardwoods

Pricecutter.com

Prime Estimating and Software Services, LLC

Pro.Woodworker.com

Pro100

Professional Hardware & Supply Co.

Quality VAKuum Products, Inc.

Quick Machinery Company

Quickscrews International Corporation

QuickScribe

QuickWood

QuikDrawers

Quis Machinery

R&R Drummond, Inc.

R.A.W.

R.D. Billhofer Company

Rangate

Rawles-Aden Lumber Corp.

RazorGage

Restoration Specialists

Rex Lumber Company

Riethmiller Lumber

Ritter Manufacturing Inc.

Rockler Woodworking and Hardware

Roger Shaw and Associates

Rose Machinery



WOODWEB DISCLAIMS any and all RESPONSIBILITY and LIABILITY for the accuracy and application of the information below. Readers agree to evaluate the significance and limitations of the information provided, and accept full responsibility for the application of this information. Read More ...

Would you like to add information to this article?
Interested in writing or submitting an article?
Have a question about this article?



Stitches Telegraphing Through Cherry Veneer       Veneer pros help troubleshoot an puzzling bleed-through problem: stitches showing through over time in a Cherry veneer layup. January 11, 2007

Question
Check out the zigzag stitch on the center seam in the picture below. This is F/C fig. cherry with finish. Panels are manufactured as 1 ply cherry face with Kuper Stitch and glued with phenolic glue to 2 plies poplar. Panels are sanded and photographed before shipping to customer with no visible sign of bleed through. After customer applies finish, this bleed through begins to appear, after several months on most panels, during the cabinetmaking stages. All efforts to reduce UV have been taken. We cannot reproduce this in our face veneer before finish. This has also been seen with qtr. Honduran mahogany, aspen and eucalyptus, but mostly cherry. Any ideas?


Click here for higher quality, full size image

Forum Responses
(Veneer Forum)
From contributor C:
If you are making the panels, press them with the glue thread up (outside). If you have a vendor making these, insist they use a Diehl splicer or similar. With thin veneers and a good sanding job, this is a common result using stitchers. For our panel products, we only use stitcher joints for backs or other low quality surfaces.



From contributor R:
What is the material used to make the thread on zigzag stitching of veneer, and will it fill up the sanding belt when the final sanding is done after pressing? I have seen this defect on stock hardwood veneer from my industrial suppliers before, but it seems to be that as I tried to sand it out (thinking it is leftover from factory sanding), what actually happens is that the veneer has been sanded through. To the questioner: could it be that you are sanding too much veneer off after pressing?


From the original questioner:
Thanks. No, I don't believe *we* are sanding off too much face veneer. The customer applies the finish sand and gloss finish to the panels. We only do a pre-sand to remove most of any white veneer tape that may be used. The idea of applying the Kuper Stitch to the face side sounds strange, but I'll talk to others here to see if that sounds possible. I think I'd also question the amount of buildup on the sanding belts the stitch would cause? Also, we manufacture our own panels. We have a glue weld seam splicer that can be used on certain species, but not all customers like it. The glue joint won't accept stain the way the veneer does, so they prefer the stitch. It's only after much time that the stitch begins to appear.


From contributor C:
Quick reply:
1-Nylon thread with a hot melt type of glue.
2-Will clog belts. Could remove after pressing with a hot iron and plastic scraper.
3-Of course it is sanded too much, but you should be able to sand 50% of the veneer away if needed. Light woods will telegraph the thread.

There are many people, especially in Europe, that use these machines. I would rather not have this as a potential problem. It could be more heat and pressure is needed in the press you are using. Have to experiment. Maybe you should just buy faces spliced with an edge gluer.



From contributor C:
If you are getting glue marks after staining with your edge gluer, you are doing something wrong. We do many hundreds of panels a week and rarely have that problem. Even with dark finish on cherry, etc. (notice I said rarely).


From John Van Brussel, forum technical advisor:
What was the thickness of the cherry veneer? How much veneer was removed in sanding? Does the customer sand further? Was the glue thread clear or a dark color when applied to the veneer? Which glue thread are you using? 1220 or 2210? What type of glue was used for pressing? What pressure, temperature and time were used for pressing?


From the original questioner:
The raw veneer is .0195-.205" thick. We remove a max of .003-.004" from the face side of panel. Our customer definitely applies a finish sand - can't tell you how much they remove? Our current thread is a clear 1220 - we've used this for years. We recently got a sample of 1210 and are considering switching - we understand it has half the glue. We use a PGF glue for pressing our face veneers. For a 4x8 panel - 280 psi, 300 degrees, at 4.5-5 minutes press time.


From contributor C:
Wow! 280 PSI - is that correct? What kind of press is that? That would be 1,290,240 lbs pressure on a 4x8 or 640 tons of hydraulic pressure.


From the original questioner:
My bad - we have 2 types of pressure gauges on our presses. It is 280 bars. Does that make more sense?


From John Van Brussel, forum technical advisor:
I am assuming PGF is phenolic glue film. What type of press do you have? 280 bar would be 280 x 14 = 3920psi. You would need a mammoth frame to withstand the torsional forces for this amount of pressure. Do you have a chart on your press to determine the correct pressure settings for different sizes?


From the original questioner:
PFG - correct. On one press, the platen is 5x10, with 3 different cylinder settings (8,10,12) depending on length of load. For a typical 4x8, we use 8 cylinders and the manometer (bars) is set for 260-280 per the charts provided based on square inches. The chart for PGF is a 200 PSI chart. Does this make sense? We've pressed this way for years.


From contributor M:
The delayed exposure of your stitcher thread may be due to the residual glue left by the thread, which has deposited adhesive in the pores of the cherry veneer. The delayed "revealing" of this condition could be caused by the photo reactivity of cherry. That is, as the cherry darkens, the stitch pattern is revealed because the glue is blocking, masking or "clogging" the cherry and preventing it from changing color.


From the original questioner:
Yes, that's the opinion we're leaning towards also. Our recent decision is to try the same thread with half the glue on it. We'll be trying that in the next few weeks to see how it handles, if it holds the seams as well, etc.
Have you reviewed the related Knowledge Base areas below?
  • KnowledgeBase: Knowledge Base

  • KnowledgeBase: Veneer

  • KnowledgeBase: Veneer: Processing And Manufacturing




    Would you like to add information to this article? ... Click Here

    If you have a question regarding a Knowledge Base article, your best chance at uncovering an answer is to search the entire Knowledge Base for related articles or to post your question at the appropriate WOODWEB Forum. Before posting your message, be sure to
    review our Forum Guidelines.

    Questions entered in the Knowledge Base Article comment form will not generate responses! A list of WOODWEB Forums can be found at WOODWEB's Site Map.

    When you post your question at the Forum, be sure to include references to the Knowledge Base article that inspired your question. The more information you provide with your question, the better your chances are of receiving responses.

    Return to beginning of article.



    Refer a Friend || Read This Important Information || Site Map || Privacy Policy

    Letters, questions or comments? E-Mail us and let us know what you think. Be sure to review our Frequently Asked Questions page.

    Contact us to discuss advertising or to report problems with this site.

    To report a problem, send an e-mail to our Webmaster

    Copyright © 1996-2008 - WOODWEB ® Inc.
    All rights reserved. No part of this publication may be reproduced in any manner without permission of the Editor.
    Review WOODWEB's Copyright Policy.

    The editors, writers, and staff at WOODWEB try to promote safe practices. What is safe for one woodworker under certain conditions may not be safe for others in different circumstances. Readers should undertake the use of materials and methods discussed at WOODWEB after considerate evaluation, and at their own risk.

    WOODWEB, Inc.
    RR4 Box 265A
    Montrose, PA 18801

    Contact WOODWEB