# Black light fluorescent tubes



## rockersuk (Feb 2, 2009)

Black light fluorescent tubes were can i buy them in the uk as im thinking of building my own screen exposure unit

thanks for looking in


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## Dyfrig (Jul 26, 2008)

I built one about a year ago. I can't remember where I bought the lights - I think it was from a local shop. I think you can only buy 20w bulbs for the size I made (around two foot) but you will have to buy 18w fittings.

These look ike the correct ones: 

F20T12BL350 2ft 20W UV Tube - Linear tubes - Ultra-Violet & Infra-Red — (UK) Light bulbs, halogen lamps, spot lights and tubes by mail order in the UK

It can take a while to expose with these.

Let me know if you need any more help.

Dyf


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## RichardGreaves (Nov 7, 2006)

*Try*
"BL" blacklight type fluorescent lamps emit both visible light and UV but are formulated to be rich in UV-A output. Please don't buy 15 & 20 watt lamps when 40 watts are available.


*Homework - Top Bulb a USA company*
Blacklights

You have to put UV in the search box
http://www.topbulb.com/find/prod_list.asp_Q_intSubCategory_E_771



*GE*
GE Consumer & Industrial Lighting: Ask Us: FAQs - Other Lighting Information


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## ShirlandDesign (Nov 29, 2009)

I built my own exposure unit after a supply rep accidentally said I could replace the bulbs (on their unit) with lizard lights. On this side of the pond Pet Smart has T4 20w florescent UV tubes for about 20 bucks apiece. I put a bookcase on its back, got the electrical fittings and switches from home depot, poped in a piece of table glass and it works great. The only trick was wiring preheat switches from scratch. If you need a wiring diagram for preheat just let me know.


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## BroJames (Jul 8, 2008)

The UV florescent lamps we can find here are BLB type or those black colored lamps. I think exposure will take longer compared to those BL UV-A lamps. Has anyone used these BLB lamps?


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## RichardGreaves (Nov 7, 2006)

*Homework*

BLB lamps filter white light and cost more than BL lamps. If you look at the spectrum graphs you will see they have the same basic output.
Blacklights

In post#3 at the GE link:

_*What's the difference between a blacklight and a blacklight-blue bulb?*
Blacklights are bulbs made with a special glass that filters out most visible light; instead, they emit a specific type of ultraviolet light called UVA. Blacklights are good for making certain substances glow that would normally be invisible. For example, you may have had your hand stamped at an amusement park with an invisible ink that, when viewed under a blacklight, glowed a bright neon color. Blacklights are available in Fluorescent and Incandescent. Fluorescent Blacklights are great to use for a party or blacklight poster; Incandescent Blacklights are an inexpensive way to create a party atmosphere._

_Blacklight-blue bulbs are designed with a special deep-blue glass that does a better job of filtering out visible light than regular blacklights, producing the maximum amount of ultraviolet light possible. If you're looking for a blacklight that produces the minimum amount of visible light for an especially sensitive area, blacklight-blue bulbs are an ideal choice._


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## BroJames (Jul 8, 2008)

RichardGreaves said:


> *Homework*
> 
> BLB lamps filter white light and cost more than BL lamps. If you look at the spectrum graphs you will see they have the same basic output.
> Blacklights
> ...


I've googled before but failed to get the information you posted (link) - only BLB's are not the right type. BTW, I use halogen.

So, having the same UV wavelength, BL and BLB lamps should practically be the same for exposure purposes (aside from cost variation) if not better (quote in blue). ???


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## RichardGreaves (Nov 7, 2006)

_"only BLB's are not the right type. BTW, I use halogen."_

OK, but you asked about fluorescent lamps in post#5
What do you mean by the right type?*



Homework*

BLB lamps filter white light and *cost more than BL lamps*. 

If you look at the spectrum graphs you will see *they have the same basic output.*

Blacklights


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## BroJames (Jul 8, 2008)

While googling sometime back, I read from a number of sources that BLB's are not the right UV lamps for exposure units. I am not sure what was meant as no further information was given. Maybe it was due to its higher cost but I was then thinking that maybe BLB's have a different wavelength. 

What I was thinking of is that it has a lower wavelength because I was not able to find any information on the wavelength of these BLB (until I read your link). I did learn that UV lamps are generally classified into 4 types (UV A-D).

I also came across some info that actinic 03 blue lamps (or something like that) are "nice" for exposure units.


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## MotoskinGraphix (Apr 28, 2006)

Yes...Richard you are confusing me as well. Everything I have read says BL over BLB. BLB tubes are everywhere, BL tubes can be hard to find.

I need 12 new tubes and was about to order a case of BL. I would certainly not buy $20 lizard lights from the pet store. 

What do I purchase BL or BLB tubes?


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## ShirlandDesign (Nov 29, 2009)

Yeah, using lizard lights doesn't sound very sophisticated compared to the UV-ABCD debate. But by the same token, while your splitting UV hairs, I've been burning pretty much perfect stencils, and then.... oh, yeah actually printing shirts.


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## MotoskinGraphix (Apr 28, 2006)

A $20 tube compared to an $8 tube is simple math. I didnt say the light isnt sophisticated but the price is stupid. I need 12 so you compare $240 or $96 bucks.


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## RichardGreaves (Nov 7, 2006)

RichardGreaves said:


> *
> Homework*
> BLB lamps filter white light and *cost more than BL lamps*.
> 
> ...


BroJames asked about fluorescent lamps.

The target for screen exposure is invisible UV-A.

BroJames told a story about a mystery Internet search that said "BLB's are not the right UV lamps for exposure units."

I answered with 2 specific reference links that explain the difference between BL & BLB lamps. A known brick and mortar vendor and lamp manufacturer General Electric.

If you look at the spectrum graphs you will see *they have the same basic output.* For screen making they perform the same. BLB filter visible light, so there is no visible reassurance that they are working. BL has plenty of useless, (but free), visible energy. They perform the same. If the price is different, that is not a performance choice.

This site caters to many novice users, all over the world, that buy 15 watt grow lamps, not 40 BL watt lamps, (the poster above is going to go with 18 watt lamps), so I try not to presume to "tell" screen makers what to buy, but screen printing facts so people can understand what there choice actually is. 

Everything Ive written also says BL over BLB. 

In the fluorescent range, I suggest 40 watt BL lamps, 4" from the glass. BL is a specific lamp type, compared to "gro-lights". In the USA, I suggest Top Bulb, located in the middle of the country. Price is relative on a lamp that useful for 10,000 hours. 10 years at 4 hours of exposure per work day.

MotoskinGraphix is lucky, he can buy from Top Bulb, BroJames, not so much. If BL tubes can be hard to find in your area, you're forced to choose the more expensive BLB.


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## RichardGreaves (Nov 7, 2006)

MotoskinGraphix said:


> A $20 tube compared to an $8 tube is simple math. I didnt say the light isnt sophisticated but the price is stupid. I need 12 so you compare $240 or $96 bucks.


What's the UV output of the "lizard lamps"? IF, there is little invisible UV-A energy, it's not actually a bargain. I'm very interested in any lamps UV output graph. [email protected]

Now, IF you buy one of each, you can actually test the lamp power to cure your actual emulsion.


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## MotoskinGraphix (Apr 28, 2006)

Or lightbulbsdirect.com


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## MotoskinGraphix (Apr 28, 2006)

I am pretty sure reptiles enjoy uv-b light.


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## RichardGreaves (Nov 7, 2006)

UV-B (320–280 nm) is below the usual range (365 nm) that is useful to screen makers, but there will probably be some usable UV energy for screen making.

UV-B does much more harm to eyes & skin than UV-A which is why it's used for germicidal treatments. Wear eye protection.

If it works, it works. That's why some people use photo floods that can take 45 minutes to expose a stencil.


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## BroJames (Jul 8, 2008)

RichardGreaves said:


> BroJames asked about fluorescent lamps.
> 
> The target for screen exposure is invisible UV-A.
> 
> ...


It is not a mystery and definitely not a story. I have encountered a few phrases something like "use the white and not the black one". 

By releasing more energy do BL lights generate more heat?


The data below, lists the peak of BL at 352nm and BLB at 352nm or 368nm. is there more than type of BLB?

Just thinking out loud: Since output is the same, I wonder why they recommend BL for _photosensitization and photochemical reaction applications and not have the same recommendation for BLB? Is cost difference the reason? _

*Does anyone have information, or can anyone make an informed guess, on what the UV reading would be at 3", 12", etc?*


*Blacklight Bulbs
*Low-Pressure Mercury Arc Lamps

UVA wavelength range: 315nm - 400nm
Peak: *352nm*
Used for: photosensitization and photochemical reaction applications and insect traps. Output includes visible light.
























*Blacklight Blue Bulbs
* Low-Pressure Mercury Arc Lamps

UVA wavelength range: 315nm - 400nm
Peak: *352nm or 368nm* 
Used for: tests, inspections, examinations, stage illumination. 
Deep blue filter glass absorbs visible light, transmits near UV.


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## RichardGreaves (Nov 7, 2006)

Your searches were a 'mystery' because you didn't list Internet reference links like MotoskinGraphix and I did.

"use the white and not the black one" is helpful, but a quote without a reference. Your references above link back to Top Bulb.

Your reference for my statements is SGIA Academy Member Richard Greaves who puts his phone number and email in his profile.









BL lamps do not release more UV-A energy. 

*Heat*
Fluorescent lamps do not generate heat like incandescent lamps. You can touch one. Electricity running through a tungsten filament heats the filament to about 1,000 degrees F. Don't touch one.

*Inverse Square Law*
There is a principle in physics called the inverse square law. Sound and electromagnetic radiation like UV and IR energy all follow this law. Energy diminishes by the square of the distance.

The source doesn't change it's intensity, so the same amount of energy has to be spread over a larger area. Imagine you have one apple pie for yourself. Now imagine 3 friends visit. Same amount of pie, but it is used in 4 times the area. 1/4 per person. 

If you measure the energy at a known distance, then double the distance, the surface will receive 1/4 the original measure. 

The square root of 2 is 4. The inverse of 4 (4/1) is 1/4.

Remember that watts of electricity in, has little to do with the watts of invisible UV-A energy out.


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## BroJames (Jul 8, 2008)

Sources and links were not listed because I did not bother to bookmark them and it was more than a month ago. Anyway, I am sure it will pop up somewhere and I'll link them. But it probably won't be of much use since I don't recall them to be scientific data but more of statements which is why I sought clarification here.

As to science let's just say I fared poorly in school. When you say BLB has a blue coating that filters visible light I was thinking of the "blue" in the a curtain or shade blocks light and reduces heat.

The inverse squares law is easy to understand though.


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## RichardGreaves (Nov 7, 2006)

Let's just say, you can come to this forum and get plenty of help. Even in your own language. I only write in English.


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## MotoskinGraphix (Apr 28, 2006)

I would have to agree with BroJames in that everything I've read said BL over BLB. I will also mention nothing scientific was ever posted or mentioned but if the wavelengths are the same no problem.

Thanks Richard for clearing up the question with reasonable and understandable info.

So there you have it kiddos...straight from the man that killed rubylith.


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## RichardGreaves (Nov 7, 2006)

Not Rubylith, but Amberlith. LOL. Thanks for remembering......

Everything I've written promotes BL over BLB and I posted the GE & Top Bulb specs as tech data.


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## BroJames (Jul 8, 2008)

Thanks

You all have been very helpful especially the link of Mr Greaves providing info that the UV output of BL and BLB are actually the same.


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## BroJames (Jul 8, 2008)

Mr Reeves,

The following is one of those pieces of information I come across from time to time that says BLB (as I understood blacklights refer to)is not the right type for exposure although, as can be seen in the link you provided, that it has the same wavelength as BL lamps.



jeffie said:


> Hey, Im new to this fourm... however i followed a link from our emulsen (i know my spelling)supplier that led me to so called black lights. our unit holds 12ea 40 watt floresent bulbs I got from a lighting supplier exposure time went from 25 min to 5-6 min. (black light vs regular "soft white "post back and i'll provide more details...jeff


You've been very helpful and I hope you can help shed further info.

Regards


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## RichardGreaves (Nov 7, 2006)

Any lamp with the descriptor "white" in it, are intended to illuminate living and work areas with a "natural" light. "Soft" White is the most pedestrian white light used for general or unimportant room light, compared to premium lighting.

Black light is rich in the invisible UV-A energy that stimulates sensitizers. "jeffie" just mentions the generic term for UV-A energy.

It's no surprise that his exposure takes less time when he uses blacklight compared to when he used soft white lamps, just like I wouldn't be surprised if he told me a fire hose filled a 5 gallon pail faster than a medicine dropper.


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## BroJames (Jul 8, 2008)

RichardGreaves said:


> Any lamp with the descriptor "white" in it, are intended to illuminate living and work areas with a "natural" light. "Soft" White is the most pedestrian white light used for general or unimportant room light, compared to premium lighting.
> 
> Black light is rich in the invisible UV-A energy that stimulates sensitizers. "jeffie" just mentions the generic term for UV-A energy.
> 
> It's no surprise that his exposure takes less time when he uses blacklight compared to when he used soft white lamps, just like I wouldn't be surprised if he told me a fire hose filled a 5 gallon pail faster than a medicine dropper.


Sorry I misread that post. It did say from 25min to (down to) 5-6 min


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## BroJames (Jul 8, 2008)

RichardGreaves said:


> BroJames asked about fluorescent lamps.
> ...
> MotoskinGraphix is lucky, he can buy from Top Bulb, BroJames, not so much. If BL tubes can be hard to find in your area, you're forced to choose the more expensive BLB.


Just an update. Finally, and this has been the case for about 4-6 months now, UV fluorescent is available at hardware chains here in the Philippines. An 18w UV fluorescent cost about US$4.20 a piece. So far, only 1 brand(Toshiba blue) is available at these hardware chains.


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## RichCustom (Jun 13, 2010)

I too have been doing some research and considering using GE F40T12/BLB bulbs which are readily available at local big box building supply stores over the more often recommended GE F40T12/BL (white) bulbs. As has been mentioned here several times the wavelength is nearly identical for both bulbs but the irradiance or "Spectral power" of the BLB bulb is much lower than the BL (white) bulb. 

Not having done any tests and limited research indicates that the the higher output of the F40T12/BL bulb should be the better choice unless I am still missing something. Perhaps the only difference is that the BLB bulbs will perform just as well but will probably take a bit longer exposure time than the higher output of the BL bulbs. Maybe someone more experienced can confirm my thinking.

https://www.interlight.biz/Catalogs/*GE*/*GE*_*UVA*_Bulbs.pdf


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## BroJames (Jul 8, 2008)

A colleague here uses the BLB and his exposure is 2-1/2 minutes 6" distance. That should make BL and BLB practically the same(I think) in terms of exposure time. The obvious difference (or the major difference) seems to be the cost.

In the US, wouldn't shipping from other states be cheaper than the premium of BLBs?


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## RichardGreaves (Nov 7, 2006)

In general terms, Blacklight (BL) & Black Light Blue (BLB), lamps are both low pressure mercury arc lamps with UV output in the same 315-410 (UV-A), nanometer range.

BL lamps emit visible light but BLB lamps use blue glass that absorbs/filters visible light, but transmits the invisible UV energy that causes a reaction with sensitizers.

BLB lamps often cost twice as much as BL lamps.

A 40 watt fluorescent lamp emits less than 9 watts of diffused UV energy. A multi-lamp, low energy, fluorescent exposure unit is suited to large area, low resolution images like signs. Low resolution textile printers buy them because the are the least expensive.


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## RichCustom (Jun 13, 2010)

Thanks for the responses from you both. here in Denver I can get the BLB bulbs from the local big box building supply stores for about half of what BL bulbs cost at the specialty lighting companies. My specific exposure unit is a National XP-5000 that uses two F40T12 bulbs in addition to a single 1000W quartz. The BL bulbs are shot so I am planning to replace them with the readily available BLB ones.


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## RichardGreaves (Nov 7, 2006)

*Re: Blacklight fluorescent tubes*



RichCustom said:


> here in Denver I can get the BLB bulbs from the local big box building supply stores for about half of what BL bulbs cost at the specialty lighting companies.
> 
> My specific exposure unit is a National XP-5000 that uses two F40T12 bulbs in addition to a single 1000W quartz. The BL bulbs are shot so I am planning to replace them with the readily available BLB ones.


Could you be more specific for our forum friends reading at home. Which big box store? What lamp prices?


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## BroJames (Jul 8, 2008)

Greaves, thanks for recommending the stouffer at every chance you got. I had a printing lull the past months, but recently switched to a 500w mercury from 250w and found the stouffer really helpful. Will try another emulsion brand, and trying an exposure setup with a separate vertical "top", so I still have to determine the "best" exposure time for my final setup and emulsion.

Back to topic. 

The 9w diffused UV is for a 40w UV fluorescent? Would you have information on the UV-A radiated by other type of lamps? I think I read some time ago that an incandescent bulb emit a little less than 1% UV. 

Regarding the dual-lamp exposure unit that kevin has, that uses a main 1000w bulb plus a few UV lamps on the sides, would you have more info on this? 

I used to use a 500w halogen, a 250w mercury, and a 500w mercury recently, all single point UV systems, but the main problem is expsosing taped transparencies. 

I am still using an A4 printer so quite a number of images have to be taped together. With a single point system, the edges of the transparencies sometimes showed up as solid (or opaque) during exposure. Meaning, they seem to block UV rays in varying degrees leaving the edge area unexposed. 

I've had some taped transparencies exposed in a fluorescent unit and these edges are usually "softer". I think it is due to the nature of multipoint UV systems. In such cases and where the image is not detailed, light scatter seems to be have some benefits.

So, how are these dual UV source units used or intended to be used?


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## MotoskinGraphix (Apr 28, 2006)

I think the side bulbs are generally used as a light table source and not for exposure. I could be wrong but I see no need for a single point exposure unit to have bl bulbs on the sides.


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## RichCustom (Jun 13, 2010)

Richard - Lowes here in the Denver metro carries the BLB bulbs and they are about $11/ea. The specialty lighting stores have the BL bulbs and they are $20 - $25 each. 

MotoskinGraphix - I'm not sure of the reason for the additional fluorescent bulbs in the exposure unit either unless it is just to get more UV. They are definitely not used for the light table as there are two other fluorescent bulbs in it for that purpose and they are both covered with a yellow guard.


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## BroJames (Jul 8, 2008)

Kevin, I think that the unit i googled months back uses halogen as the main lamp with 2 UV lamps. I also vaguely recall that the second UV source is claimed to lower exposure time.


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## pakala (Sep 7, 2011)

I have read all the comments but I'm still in considerable doubts as all the infos/terms wouldn't fit into bird size brain 
I am about to build an exposing unit but I could only find "F18t8/BLB tubes". Will be using five or six BLB tubes, 6" or 9" between the tubes and glass on top. Will it work? Time is not a factor. New to screen printing...plz help.


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## pakala (Sep 7, 2011)

I have read all the comments but I'm still in considerable doubts as all the infos/terms wouldn't fit into bird size brain 
I am about to build an exposing unit but I could only find "F18t8/BLB tubes". Will be using five or six BLB tubes, 6" or 9" between the tubes and glass on top. Will it work? Time is not a factor. New to screen printing...plz help.


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## MotoskinGraphix (Apr 28, 2006)

Put the bulbs right next to each other. 
Check out lightingsupply.com


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## BroJames (Jul 8, 2008)

pakala said:


> I have read all the comments but I'm still in considerable doubts as all the infos/terms wouldn't fit into bird size brain
> I am about to build an exposing unit but I could only find "F18t8/BLB tubes". Will be using five or six BLB tubes, 6" or 9" between the tubes and glass on top. Will it work? Time is not a factor. New to screen printing...plz help.


They'll work. BLBs are just more expensive


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## pakala (Sep 7, 2011)

BroJames said:


> They'll work. BLBs are just more expensive


Thank you...brojames


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## RichardGreaves (Nov 7, 2006)

*Re: Black light fluorescent tubes SPACING*



pakala said:


> I am about to build an exposing unit but I could only find "F18t8/BLB tubes".
> 
> Will be using five or six BLB tubes, 6" or 9" between the tubes and glass on top.
> 
> ...





pakala said:


> I am about to build an exposing unit but I could only find "F18t8/BLB tubes".
> 
> Will be using five or six BLB tubes, 6" or 9" between the tubes and glass on top.
> 
> ...


Yes, it will work - especially if _*time *_isn't a factor. As I wrote in posts above, BLB lamps use blue glass that absorbs/filters visible light. This blue glass costs more than clear glass.

As *MotoskinGraphix* wrote, closer together will give you an even coverage of UV energy. Spacing wider than 6" will give you high & low concentrations of energy - washboard effect.









Typical spacing in a commercial unit.


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## pakala (Sep 7, 2011)

Thank you. I'm thinking of leaving 2"-3" space between the tubes. 6" from tube to glass. Does that sound ok?


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## BroJames (Jul 8, 2008)

I am sure there is no hard and fast rules but the commercial units I've seen has a spacing more like 3-1/2" to 3-3/4" CTC or measured from center to center. It measures the same if you measure it from left edge to left edge or right to right.


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## RichardGreaves (Nov 7, 2006)

pakala said:


> Thank you. I'm thinking of leaving 2"-3" space between the tubes. 6" from tube to glass. Does that sound ok?


My picture in Post 43 shows my suggested space of a lamp (1 inch), between each lamp. 

4 inches from glass is normal. 6" would double exposure time. 8" = 4 times as long compared to 4 inches. You, get to choose.

Penetration of UV energy through the stencil isn't 'linear'. This is why the measurement of UV exposure isn't linear. The deeper the UV energy has to penetrate, the longer it takes based on the rule of physics called the "Inverse Square Law". 

If you double a distance energy has to travel, it takes *4 times* the energy - NOT double. 

Many low energy UV lamps may never penetrate thick mesh & stencil.


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## pakala (Sep 7, 2011)

BroJames said:


> I am sure there is no hard and fast rules but the commercial units I've seen has a spacing more like 3-1/2" to 3-3/4" CTC or measured from center to center. It measures the same if you measure it from left edge to left edge or right to right.


Thank you...I appreciate ur help. Wht do you mean center by centrr? Is it oj if I just leave 2" on the edge and start placing the tubes with 3"?
I'm sorry for my ignorance


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## BroJames (Jul 8, 2008)

RichardGreaves said:


> ...
> Many low energy UV lamps may never penetrate thick mesh & stencil.


That is what some people do not understand. Although they equate wattage = higher electric bills, wattage also = better penetration. However, UV lamps should be enough for most people and in most situations.


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## pakala (Sep 7, 2011)

RichardGreaves said:


> My picture in Post 43 shows my suggested space of a lamp (1 inch), between each lamp.
> 
> 4 inches from glass is normal. 6" would double exposure time. 8" = 4 times as long compared to 4 inches. You, get to choose.
> 
> ...


[QUOTE=RichardGreaves;1000281
Thank you so much Richard. Will get to work n the exposure unit. This is something very new to me so a little apprehensive and want to be sure of everything.(as i won't be able to get more uv tubes). I thought screen printing would be a piece of cake but... everything is so new to me and I'm getting nowhere with my T-shirt printing plans. Anyway thanks to people like you and the forum I'll get there! Might take time but I will! You all have to bear with me cos I'm going to be posting stupid questions.


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## RichardGreaves (Nov 7, 2006)

nals,

Why won't you "be able to get more uv tubes" ?


*Buy the book*
Go to:* T-Biz Network Store
and buy "How To Print T-Shirts for Fun and Profit!" the textile screen printer's primer since 1979.


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## BroJames (Jul 8, 2008)

pakala said:


> Thank you so much Richard. Will get to work n the exposure unit. This is something very new to me so a little apprehensive and want to be sure of everything.(as i won't be able to get more uv tubes). I thought screen printing would be a piece of cake but... everything is so new to me and I'm getting nowhere with my T-shirt printing plans. Anyway thanks to people like you and the forum I'll get there! Might take time but I will! You all have to bear with me cos I'm going to be posting stupid questions.


Equipment wise, it is a piece of cake for us.


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## BroJames (Jul 8, 2008)

pakala said:


> Thank you...I appreciate ur help. Wht do you mean center by centrr? Is it oj if I just leave 2" on the edge and start placing the tubes with 3"?
> I'm sorry for my ignorance











UV Exposure Unit Plan - T-Shirt Forums

You will be buying 5-6 UV tubes right? Do as Richard suggested, 1" in-between tubes is fine unless you will be printing on larger fabrics. Actually, for t-shirts 4 tubes is often enough. 5-6 for all over prints.


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## pakala (Sep 7, 2011)

Thank you so much brojames. I have bought the uv tubes (F18t8/blb). I could only only find those.
@Richard, uv tubes aren't available where I live.... had to drive 600 kilometers for it and it rather expensive (around $85 for six tubes with fixture)


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## pakala (Sep 7, 2011)

Thank you so much brojames. I have bought the uv tubes (F18t8/blb). I could only only find those.
@Richard, uv tubes aren't available where I live.... had to drive 600 kilometers for it and it rather expensive (around $85 for six tubes with fixture)


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## mmcmanus (Aug 8, 2011)

I know this question is a little off topic but my question goes along with what Richard Greaves was saying about inverse square law. First off let me say I am a newbie. I am looking to build an exposure unit. I split between florescent uv bulb and a Metal Halide units. I am having trouble sourcing 1000w bulbs for the metal halide. With that said and the principles of the inverse square law could I reduce the distance to the bulb from the screen and say use a 100w or 2 100w metal halide bulbs. In reference I am using Ulano easy film 50. The technical data sheet gives a base screen burn time of 97 seconds with a 1000w metal halide at a distance of 40 inches.


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