Screen printing painted wood

[jeff]

Hey all. Just wondering if anyone has ever done screen printing on painted wood. We produce semi-large volumes of signs, some carved,some not...we have previously used a vinyl cutter, but slow-go! Any advice on this would be greatly appreciated!

[rb99]

What sort of volume are you looking at?

How many colours?

Size?

RIB

[jeff]

volume varies depending on time of year.. probably anywhere between 100 and 200 pieces of about 20 inch squares, 300 or so 10 x 24 inch signs, etc... usually use only one color at a time.. black on some, brown, or cream.. thanks for any advice

[njandpa]

I can answer any questions you have. Can you narrow such an open ended question a little?

[dakers]

we do screen printing on painted mdo.
usually 32''x48'' three color two sides using nazdar 5900 enamel with all their recommended reducers, etc for the 5900. We prime the mdo with xim 400w then a high quality oil base enamel.
we use a one man squeegee to print with using a sharp medium durometer squeegee. have been doing these since the 1970's with good results. These are for real estate auction signs that we hand letter the middle sections. they never seem to wear out. we use an indirect stencils and direct stencil or the ulano laquer stencil the enamel does not eat the laquer stencils as long as we are careful about the thinnners.so we can use about anything with the 5900 nazdar. i have used hand cut paper stencils as well.

[dakers]

I forgot to mention. lately we have switched to hdo because the mdo has not had the same quality it had in the 70's and 80's it comes to us with a bow so it does not lay flat on the screen table. the hdo seems to come flat. but you are doing smaller pieces so that may not be a problem. we were using the 3/8'' HDO. I think they were winding up around $90. each in quantities of 100. We used two coats of primer and two coats of enamel.
smooth and flat were the main ingredients we were looking for.

[rb99]

It would be nice to know your volume. The process can be used, but it is also not very pleasant in my opinion.

There is the purchase of the equipment and screens and inks, films, thinners, additives, and other supplies.

The process is fast when printing, but takes time to set up, resister and get started, and clean up.

You would need a clean area, no dust. Also professional ventilation is a must. If you make your own images on the screens, you will need a darkroom, some expensive exposure equipment, and a large sink to rinse the images. You can go direct or indirect when making the screens. Direct is coating the screen with a light sensitive liquid. You then need the image on a clear film in an opaque medium that will not let the intense UV light penetrate the dried coating underneath it. You place the image on the screen where you want it, and expose the screen to uv lights. A vacuum is required to get a sharp image. Then you rinse the screen and the film that was not exposed under the image on the clear film gets rinsed away. The UV cured areas remain. Indirect is very similar, but the coating on the screen is replaced with a roll of film that you cut to size, expose, rinse, then apply to the screen and dry. When it is dry the clear plastic carrier is remove, and the screen image is made.
Then the screen needs to be blocked out around the edges and some touch up may be required.

Printing can be very toxic. Then there is the clean-up. All ink must be 100% removed from the screen with thinners and rags. I always wore those canister style airs masks. I remember I also always had a sore nose. It was always raw on the inside and when I quit that problem went away.

Racks are required to stack the pieces for drying. You can buy nice ones or make your own. Either way they take up space. When the signs are drying they also give off fumes...I had a large automotive spray booth that I wheeled the loaded racks into and could close the doors and vent them.

Static electricity can be a problem as well. You will need to factor lost material and over-runs as you cannot make exactly the number required due to printing error etc.

I don't want to deter you from it, but let you understand the scope of what you are getting into.

You may find a good deal on all the equipment as many screen printers are getting out of it and going digital, or their markets have dried up due to digital.

I would source out a printer and get them to quote on the printing. Depending on your market they may be very competitive, and save you the troubles I have described above.

Others may have different methods and viewpoints so take what I have said as only one opinion please.

Hope this helps.

RIB

[dakers]

here is a bad jpg of a cheap drying rack we used for 18x24 signs. it was just plywood with notches. this just sat on floor and the signs just fit loosely in notches at an angle but notches not deep enough to touch the screen print. we could print one color both sides before racking
50279.jpg

[dakers]

side note. we used to buy 12xx silk for silk screen printing and use hand cut indirect water sol ulano stencils.
the water sol stencil would stick so good to silk because the silk abosorbed moisture. then they came out with the mono and multi polys which did not absorb moisture so the water stencils did not stick well so they came out with chemicals and abrasive agents to help abrade the poly fabric so the stencil would stick better. I think the last time i used an indirect water soluable photo stencil i just used comet cleanser and some sandpaper to get the adhesion better but it was never good adhesion. I agree with Mr.Bouchard. Screen printing can be technical and daunting today. I sub out the stencil process when we need it done.
Back in the day when we used hand cut paper stencils we screened paper signs for grocery stores and political signs. we would save the stencil and use it about 4 to 5 times. I really do not know how to do screen printing the modern way very well but it was the first job i had in a sign shop in 1967.