# Homemade exposure unit suggestions!



## brianmot (Dec 24, 2008)

Hey guys,

I have a few questions for you experienced screen printers out there. I outsource the bulk of my screen printing but i have recently picked up a bundle of screen printing supplies for cheap. I will mainly be using them to print small run shirts, sleeve prints and posters. I wont be doing much half toning but would like the option to. My expertise is in preparing files for printing and not printing so i hope you guys can help 

Note: I will mainly be burning 20 x 24 inch frames. I am also only burning a few frames a month. water based inks.

*Main question:* 
a.) Should I go with the single source 400/600 watt halide light from 36" away? (a bit more expensive)

b.) can i get away with one or two 500watt halogen? (like seen here Exposure Unit)

c.) or should i go with the 8 rows of 20watt UV Blacklight Fluorescent bulbs from 2" away?

Keep in mind that I am not doing this for production so i don't necessarily need 30 second burn times.

Should i get a vacuum unit? I hear all it takes is some pond liner and a shop vac. or will some foam and a few bricks work?

I read that Ulano RLX Dual Cure Diazo is a good emulsion to use. What are the differences in the brands? do some hold up better? expose quicker? last longer? apply thinner? how is it different from QX-1?

Any suggestions are tips appreciated.


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## brianmot (Dec 24, 2008)

Do you always get undercutting from option c)?


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## thutch15 (Sep 8, 2008)

brianmot said:


> Do you always get undercutting from option c)?


The key to undercutting is to have no space between the emulsion and the transparency, but with mutli point lighting units you could never clear up 100% of the undercutting. 

For basic jobs with good contact between transparency and emulsion you should not have to many problems. Halftones can even be don't with something like you "C" option. Just a little tougher and not perfect.

Assuming you don't have unlimited funds I would suggest starting basic and working your way up slow. I started with a 500 w light and then went to a mutli bulb UV light and now I am building a 1000 watt MH light unit.

With a good dark transparency and good contact with emulsion I don't see how a 500 halogen and 1000 MH would differ other than time.


http://www.t-shirtforums.com/t-shirt-articles/t108270.html


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## iwhdesigns (May 29, 2010)

I was recently asking the same question and for me I found the best was to go right for the metal halide light. The thought was if your going to do it do it right first.


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## brianmot (Dec 24, 2008)

I am going to build the unit like seen in B.) and exchange the 500w halogen lamp for the halide when i pick one up. Ill post pictures when its up and ready. thanks.


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## texasagswife (Sep 28, 2010)

Brian, I made a homemade unit. No vacuum blanket. 1000W Metal Halide light bought from an online company that sells lights for hydroponic or indoor plant growing. I made mine for less than $300 (and most of that cost was in the light). I used a simple 2x4 frame with tempered glass top (to take the heat).

I calculated the distance based on the size of glass top, so I would not have any underlap. It burns a screen in 10 seconds (I use Chromablue emulsion).

Here are some pics. It actually is for sale right now, but I don't know if it's exactly what you are looking for...but, maybe it can give you some ideas.


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## brianmot (Dec 24, 2008)

texasagswife,

Thanks for the pictures! 

-Brian


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## cv.graphink (Nov 25, 2010)

here's plans for a 500 watt exposure unit. thats what i use.
How to Make an Exposure Unit | Printwear


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## brianmot (Dec 24, 2008)

Thanks Chris. I already bought the wood to build something like this next saturday.


How long does it take you to expose a screen? what emulsion are you using? how far is the bulb from the glass? 

also, where did you get your 500w halogen bulb from? home depot or a similar store?

I just bought a stouffer 21 step wedge transparency so i can make sure my screens are spot on. just curious though. Thanks.


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## cv.graphink (Nov 25, 2010)

12-13 mins with one 500 watt and then i cut that time down by using two. i had some home depot 500 watt lights that had a stand. i got them from someone else who bought them and had them in their garage. emulsion? aqualsol hv screen printing emulsion. however i wouldn't trip too much about that. i've tried others and didn't have any big problems. my lights are 24" from the screen. i place the screen on the bottom of the stand, place my film on top, next i place a piece of glass on top to firmly hold down the film to the screen, and finally when i'm ready to expose i turn on my lights. bam.


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## brianmot (Dec 24, 2008)

Awesome. I was worried that the 500watt halogens were going to take 30-45 mins to burn a screen. doing emulsion tests would take forever. 10-15 minutes is fine.

from your description it seems like you have the screen on the ground, positive and glass on top and light shining down on it? is that right?


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## cv.graphink (Nov 25, 2010)

that's exactly how i have everything. your welcome.


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## tpitman (Jul 30, 2007)

Heat is also an issue with both metal halide and halogens, but the halogens are so slow that it's one of the bigger problems, with, in my experience, film sticking to the emulsion. Use a fast SBQ emulsion like QTX or Satti Textil PV and get your exposure times dialed in. Also, probably the best thing you can do for an exposure unit of any kind is to make a vacuum blanket. I've made two out of pond liner, and with a small shop vac and sufficient slack in it, it'll pull your screen/film/glass into such intimate contact that it should get arrested as an unnatural act in a threesome. The vacuum blanket is the singular feature that will make your stencils great as opposed to adequate.


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## SoloStampede (Aug 4, 2007)

My exposure unit consists of 8 undercabinet lights with uv bulbs. and the storage is made out of 24" x 7-1/2" bookshelves with an acrylic sheet over the top.


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## marcelolopez (Jul 16, 2007)

tpitman said:


> I've made two out of pond liner, and with a small shop vac and sufficient slack in it, it'll pull your screen/film/glass into such intimate contact that it should get arrested as an unnatural act in a threesome.


Lol..
however I have used a small fan on the side of my box, to dissipate the heat. It isn't an issue anymore, in my case.
It isn't a very elaborated setup, but it works.


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## tpitman (Jul 30, 2007)

The homemade ones I built used the unfiltered blacklights, mainly because I'm lazy and wanted to use a darkroom timer to control exposures. You can use a timer with a quartz halogen rig too, but with most homemade metal halide units, you have to let the bulb warm up before exposing the screen, and leave it on if you've got more than one screen to shoot, and incorporate some kind of a shutter to control it. I've since bought an Amergraph 150 exposure unit, and while it wasn't exactly a giveaway, I have to say it was worth the money. It measures exposures by light units, as opposed to time, and incorporates an integrator that will increase time as needed to reach the correct number of light units for proper exposure as the bulb ages and light intensity decreases.


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## Jsaladin (May 23, 2010)

Here is my new baby, did have a 1000 watt metal halide bulb and balast in it and now it has a 1500 watt metal halide bulb and ballast. Complete with a vacume hold down and pin hole lights. I burn two screens at once in 2 minutes 5 seconds with this baby. I have a built in shutter set up on a spring loaded hinge so I am not pulling a 40x60 inch peice of plywood out of the thing every time i need to expose a screen. I also put a exhaust fan in for the light, almost a must have when you have something inclosed like this!!! BUILD BIG OR GO HOME! I have an exposure area of 38x60 inches


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## buttton (Jul 27, 2009)

I made the same homemade unit w/ 500w, the only difference is I installed a small fan blowing up to the bottom of the glass to cool it. Works good.


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## BroJames (Jul 8, 2008)

brianmot said:


> Awesome. I was worried that the 500watt halogens were going to take 30-45 mins to burn a screen. doing emulsion tests would take forever. 10-15 minutes is fine....


10-15 minutes with a 500w lamp may not be a problem but why not try something that cost just a fraction more, exposes at about 1/8th-1/10th of the time, and with only half the electric consumption? I am talking about a 250w mercury vapor lamp.


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## brianmot (Dec 24, 2008)

Wow, awesome exposure units guys. I built mine this weekend and just finished the last coat of black paint (i hear if its white it sometimes reflects the light and has potential undercutting) It was SOOO inexpensive. I went to home depot with my plans, expecting to buy the 2x4s and the come home and cut them. They were glad to cut them at the store though. Exact size. (5) 8 foot 2x4 at $2.13 a piece + a $18 dollar 500watt halogen bulb, wood screws and a level came out to around $40. incredible. They didn't have the glass though. especially at my awkward size. I suggest building your exposure unit around a typical glass size, it will save you some money. Wood is cheap, custom glass is a bit more expensive.

I have all the supplies except for emulsion, degreaser and a dry rack. I hope to build the dry rack a bit later this week and get printing by the weekend. Ill be sure to take pictures.


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## 13Graphics (Jul 20, 2009)

Jsaladin said:


> Here is my new baby, did have a 1000 watt metal halide bulb and balast in it and now it has a 1500 watt metal halide bulb and ballast. Complete with a vacume hold down and pin hole lights. I burn two screens at once in 2 minutes 5 seconds with this baby. I have a built in shutter set up on a spring loaded hinge so I am not pulling a 40x60 inch peice of plywood out of the thing every time i need to expose a screen. I also put a exhaust fan in for the light, almost a must have when you have something inclosed like this!!! BUILD BIG OR GO HOME! I have an exposure area of 38x60 inches



Any more pics of it? Specifically your shutter setup...

I've got my glass, and just picked up a couple 400W MH units today. Have some rubber roofing material for the vacuum blanket, and will build the rest out of steel, and sheet metal. I have a couple ideas for a shutter, but nothing that's as elegant as I would like while still being cheap.

I'm hoping to build it with a 400w light, then if I come across a 1000 in the future I'll make the jump.


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## BroJames (Jul 8, 2008)

A couple of 400w?


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## MadMade (Nov 3, 2010)

ok listen up this will help ya out and Ive been doing it for years and it works great!
first off a vacuum is essential so yes
and go to walmart get 4 ft shop lights about six of em 10 bucks each
at walmart get plant aquarium light bulbs 2-pack 5 bucks each
plywood and go get a piece of tempered glass from a glass company with 2 1/4 inch holes in it depending draw the vacuum through the glass ( much better)on how big your exposure unit is about 200.00
rubber blanket can be made from pond liner from home depot works great

I built an exposure unit with these items and built it for around $450.00 and I can expose 4 screens 20"x20"
using ulano qx-1 in 1 minute 45 seconds spot prints and 1 minute 20 seconds for halftone and they come out nice tight and crisp!!
take my word for it WORKS GREAT nice size can burn 4 screens at once and cheap $400.00 total


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## 13Graphics (Jul 20, 2009)

BroJames said:


> A couple of 400w?


Yeah, for the price I paid it was worth it to by 2. This way if one ever goes bad I have everything to replace it.

I'll only be using 1 at a time.


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## Jsaladin (May 23, 2010)

my light is actually in a metal box. as you can see from the picture. what you cant see is that with the shutter.

Its just a lid for the box. I have 3 hinges for it to open and close nicely. 2 on the hinges are spring loaded. When you pull open the lid through the front of the box via the cable you are exposing the screens. When you are done and need to switch your screens out all you do is let go of the cable and the spring loaded hinges take care of the rest.


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## MadMade (Nov 3, 2010)

built this one out of steel with tempered glass and vacuum system
and its powder coated
lights fixtures glass steel vacuum blanket vacuum pump and powder coated with digital timer integrated 
flip a switch for vacuum hit timer wait for it to shut off done!
built my last one out of 1x2's and plywood just like this one for $379.00
built this one for 568.00
that includes everything!!!
will expose 4 screens at once in 1 minute 30 seconds using qx1

you can lead a horse to water but you can't make him drink!!!


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## marcelolopez (Jul 16, 2007)

Wow, I feel ashamed I posted the picture of my box after seen yours, guys those are professional exposure units !!!


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## brianmot (Dec 24, 2008)

How did you guys seal your vacuum blanket? 

It looks like MadMade has a made a separate top that hinges and clamps over his frames. is that how most of you guys do it? What kinda foam/sealer is that on the bottom (on top of the glass)? also, where does your pump plug into the sealer?


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## MadMade (Nov 3, 2010)

you roll the vacuum blanket under and screw it to the outside with thin strips the vacuum draws through the glass the foam seal is between the top second level top and box you lift the btwo top lids to change bulbs the foam is high density foam weatherstripping from lowes
I could post quickie blue prints if you guys would like me to!
I dont understand another thing why is your exposures taking so long I expose with plant aquarium bulbs and they arent even as powerful as un filtered black lights.
are you guys coating the screen a lot with the emulsion?
if so how many times?


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## brianmot (Dec 24, 2008)

I understand now. 

This thread was very helpful.

http://www.t-shirtforums.com/screen-printing-equipment/t123215.html

specifically this picture:









I am planning on using a shopvac for the vacuum system. I'm going to have to look for a very small nozzel attachment for it. or make one.

Im going out to buy the wood for the drying rack and the rest of the supplies for the vacuum unit.

Thanks again guys!


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## BroJames (Jul 8, 2008)

marcelolopez said:


> Wow, I feel ashamed I posted the picture of my box after seen yours, guys those are professional exposure units !!!


The most important thing is that it works.




MadMade said:


> ...
> I could post quickie blue prints if you guys would like me to!
> I dont understand another thing why is your exposures taking so long I expose with plant aquarium bulbs and they arent even as powerful as un filtered black lights.
> are you guys coating the screen a lot with the emulsion?
> if so how many times?


Why not post the blueprint? 

Coating and type of emulsion may be a factor. But even if they are the same, exposure times can still 2-3 folds both resulting in a usable washout.


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## 13Graphics (Jul 20, 2009)

I'll also ask... what are you guys using for a vacuum pump? I mean what type, how much vacuum, etc?

I have my vac pump for HVAC work, but #1 I'd rather not use it, #2 I'm afraid it will break the glass.


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## Jsaladin (May 23, 2010)

all I use is a shop vacume


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## MadMade (Nov 3, 2010)

I use a Thomas vacuum pump its probably more powerful the the hvac ones but mine draws though the glass so no worries on breaking it........prints and more pics coming soon been real busy lately

oh and I use ulano qx1 emulsion coat 1 ONE time on the print side and let it dry in my heated dry box print side down!
been printing like this for about 10 years now and Ive never had any problems.
just be sure and degrease your screens prior to coating . That prevents any chance of pinholes
hop this helps will try and draw up blueprints in the next day or so...gotta get back to work.
I love printing all night in the winter


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## brianmot (Dec 24, 2008)

Jsaladin said:


> all I use is a shop vacume


what kind of nozzle do you use at the end of the hose? Is it a standard one that comes with the vac or a custom? 

I only ask because ive seen pictures of vacuum pumps having very small hose/nozzles.

Thanks.


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## tpitman (Jul 30, 2007)

The only way your vacuum will break the glass is if the frame isn't flat. The parts of a frame that isn't flat that come in contact with the glass will exert more pressure on the glass as the blanket tries to pull the frame down. From what I've read, the pressure of the blanket against the mesh and glass is offset equally by air pressure on the other side. Sounds weird but I think it's true. Might make a difference if the seal around the frame holding the blanket didn't seal against the glass itself but against the framework the glass sits in to where there was a possibility of movement between the glass and the framework around it, if that makes sense, but I'm speculating here.


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## Jsaladin (May 23, 2010)

I have a regular shop vacume hose and then on the end I have PVC fittings to reduce the size down to 1/2 inch. Works out pretty good for me.


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## brianmot (Dec 24, 2008)

Awesome! that is exactly what i was wondering. Thanks a lot!


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## jiarby (Feb 8, 2007)

here is the shop vac connection someone posted yesterday somewhere...


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## MadMade (Nov 3, 2010)

here ya go guys no blueprint but photos
I'll try to explain the best I can if ya got questions ask

1st) the unit

2nd) the timer and vacuum switch ( note I made to power control box out of a brinks money box from wally world sorry for the blurred image but ya get the idea)

3rd) the lights(wally world just cheap shop lights and grow/aquarium bulbs) I wired them all together in the metal box (from Loews)

4th) hose connections to vacuum pump (note:holes in glass vacuum pulls from underneath

5th) vacuume pump purchased off ebay $225.00 pump for $26.00

6th) first and second top first top(bottom one with 2x4 block has glass mounted on top you lift this to change bulbs this is the one you secure to the unit with hinges)

7th) first and second top second top(vacuum blanket this one you secure to the bottom--the glass frame lid)

bought the light fixtures and bulbs at wally world 
total cost approx. $80.00
steel box but can be built out of wood for like $30.00
2x4's and plywood
glass ordered from glass co. tempered 1/4" thick with two holes in glass (could be just one hole) cost approx $200.00 (wouldn't be that much but I wanted to burn four screens at once, smaller would be cheaper)
vacuum pump and timer was purchased off ebay I got the pump for $26.00 and the timer was like $15.00 I think
misc.parts-----air hose, fittings,plugs and wire, wiring box silicone to secure glass,high density foam weather stripping to seal around first and second top
All for around $30.00

total cost would be around $381.00 give or take:
can burn 4 screens at once!
been using mine (the one you see) for over 4 years now and haven't even had to replace a bulb yet!
have any questions let me know I will try to help all I can

and remember it doesn't have to be just like this just how I built mine It doesn't have to be pretty or professional looking just my preference
build one if it works and gets the job done and you didn't have to spend a fortune for it then you should be proud of your self!!!


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## Florafreak (Sep 22, 2010)

jiarby said:


> here is the shop vac connection someone posted yesterday somewhere...


I posted that, and I also have progress photos of my build through out the whole build. 

here, hope it helps. 

Exposure unit build | Facebook


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## scubadan (Jul 14, 2010)

Justin!!! Great design! Do you have the plans available?


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## scubadan (Jul 14, 2010)

Man How I didn't see the above post is beyond me!!! But I still have a question... THe grow lights from wally world... what is the distance apart nad how far from the glass? Thanks


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## Dkenzie1 (Sep 22, 2011)

I use 6 uv florescent bulbs placed 3" from the glass. exposure time right about 15 min. Don't ask me how but I can expose halftones up to 60 lpi. Everything that I read says that I should not be able to do this without a vacuum. with the halogen and metal halide definitely keep in mind the heat factor the last thing you want is to hear a crack when you are in the middle of exposing a screen. built mine for under $175.


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## edward1210 (Nov 7, 2009)

i know this is an old thread, but can you tell me the high and wide of your box?
Thank you


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## BroJames (Jul 8, 2008)

The height of UV units is usually 6-10inches but I've seen higher and lower units. The spacing is usually between lamps is 2-1/2" to 3".




Dkenzie1 said:


> I use 6 uv florescent bulbs placed 3" from the glass. exposure time right about 15 min. Don't ask me how but I can expose halftones up to 60 lpi. Everything that I read says that I should not be able to do this without a vacuum. with the halogen and metal halide definitely keep in mind the heat factor the last thing you want is to hear a crack when you are in the middle of exposing a screen. built mine for under $175.


The advantages of the vacuum top is exaggerated. I've tried a DIY vacuum top but went back to the "weight" thing. I just figured out that I'd rather do without the vacuum noise. As to halogen and MH, I've used both. Glasses won;t crack if the unit is well ventilated.


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## MadMade (Nov 3, 2010)

4ft.X5ft.X12in. Exactly


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## MadMade (Nov 3, 2010)

Distance between double light fixtures is 1.75 inches


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