Materials Tools & Equipment: Part 1 Resist

Hi

In this section MATERIALS we are going to look at the main materials required to get up and running in your etching pursuits.

Possibly the most indispensable material is the resist, this has a number of functions and using the correct resist for your project is important and knowing the correct thickness of the resist you require for each individual technique will make your task easier and definitely save you money.

Resists comes in a number of materials from air brush mask, Fablon, (known as sticky backed plastic from Blue Peter)  vinyl used in sign making, PVC, rubber and for fine detail and photographic imagery there is photo resist, which I will look at in a separate post.

Rapid mask photo resist

It comes in a variety of sizes from A4 sheets to rolls of 1200mm wide and every size in between and no doubt wider.

It can come in ready made patterns of cut vinyl or ready exposed photo resist reusable stencils

Pre-exposed stencils.

and of course just plain old resist on a roll.

The first resist I bought was called Buttercut or Butternut (can't quite remember) I ordered around 600mm wide by 2m long, it came from a large stained glass supplier and it arrived folded into a tight parcel to fit into a jiffy bag, this was very expensive resist and was now useless for what I required it for. They did replace but do be careful with your resist as it needs to be perfectly stuck to your glass to prevent blow through which is what may happen with creases and bubbles in it.

Vinyl, PVC and rubberised resists come in a variety of thickness and understanding the thickness can be a little difficult because it is not measured in what for the majority of people are recognized measurements.

Take a look at the these pages from MDP; 

The thickness is measured in mils or microns or the symbol µm.

What does it mean;-

1 Micron = 1µm  =0.001mm or 1000th of a mm

80 µm     = 0.08mm      Light duty for glass from 2.50 per metre

180µm    = 0.18mm       Medium duty for glass from 3.00 per metre

330µm   =0.33mm         For heavy duty for stone, metal from 7.50 per metre

So a basic understanding is that the bigger the number the thicker the resist, the thicker the resist the higher the cost, the higher the cost the more you might look for a cheaper alternative when depth of the etching / carving is not an issue.

Of course this is just one way of a company displaying the thickness.
Some companies display in 1000th of a inch or thou an older measurement that is still used in the engineering world (not by me) which since decimalisation has largely disappeared but the conversion I use at work is 40 thou = approx 1mm.
1 thou = approx 25µm so from the above 80µm is approx 3 thou  180µm is approx 7 thou and 330µm is approx 13 thou.

It is not only the thickness of the material that effects the resistance to attack by the media at what can be a hugely concentrated pressures, some sticky backed plastic can be thicker than resist yet not have the resilient qualities designed into quality resist also the adhesive used plays a major part. The adhesive is designed to resist movement yet also have the ability to be easily removed, a difficult combination to achieve. 
The technical data sheet above it tells you the value's of the adhesive used.


Getting bored yet.

Knowing the alternatives and how far you can push them is an important part of the learning curve, this is where testing and practise comes in. 
I started on sticky backed plastic which is sold in Wilkinson's and other types of General stores then when I bought my 2nd used cutting machine it came with around 6 full rolls of vinyl which would have cost more than the cutter to buy. I then after practising with these cheaper resists moved onto the more expensive materials, even now I shall use cheaper / thinner resists for light etching work. Vinyl is around 50 to 70µm.

Unfortunately vinyl does have one major drawback compared with proper resist in that it is designed to stay on what it is stuck on. Ha! as we say in England "it's a bugger to get off"

Have a read, these people know what they are talking about.

Etchmaster - Understanding resist

Etchmaster - Basics of resist

Norm Dobbins - Resist

MDP Supplies UK - Prices


Application Tape

Things that go hand in hand, 
Gin & Tonic, Fish & Chips, Resist & Application Tape.

When a cut pattern of resist is transferred to a piece of glass then application tape is used to apply it to the glass hence the name application. (also called Transfer tape)
Alternatively the resist can be stuck directly to the glass, the pattern then drawn on and cut directly into the resist in this case no application tape is required.

Application tape comes in 2 different forms and many different width's 

Paper tape

Clear tape

I use both the paper type and the clear, the clear is a little more expensive and I use for the smaller jobs such as glasses or small panels where centering is important. The paper tape I use for larger flat panels where the edges require lining up and not centering.

Resist consists of 2 layers, the resist on the top and a silicone base card which it is lightly stuck too, the silicone acts as a release agent for the resist glue so it is easily removed but makes the two layers act as one for easy handling and machine cutting.
The resist pattern can either be cut by hand or machine, but once cut you need to transfer the cut pattern to the glass removing the backing card at the same time, without some means of holding the pattern together it would end up as a mess on the glass (done it).

Paper tape being applied, a application roller is not necessary but for larger pieces can be very helpful. 

No bubbles, smooth application is important and care should be taken to smooth evenly.

A hard plastic vinyl squeegees are readily available on ebay for a few pound.

The application tape is used as a third layer, base card - resist - tape, a resist sandwich so to speak. 
This resist now has adhesive to both sides so the base card can be removed without a big mess being made. 

Weeded stencil applied 

Backing base removal

Tape being removed

Off course there is are a number of techniques to achieve this which shall be looked at in a later post.

Paul

What do I need to start Part 6 Extraction.

Hi

Quite possibly the most important piece of equipment to go with your cabinet is the dust extraction system and needs to be one of your first thoughts when buying and setting up your cabinet and compressor.

The dust that is produced when blasting is broken into 2 categories.

a, Dangerous;   

This by it's categorisation is bad for your health and comes from the silica in normal sand and as I have mention in other posts should be avoided at all costs. If for some reason; maybe, ready availability, cost of more suitable materials or you just don't care, then ensure that you do have a good extraction system that collects the dust and not a blower that blows it into the outside air where anyone human or animal can breath it. O yes, don't forget you also have powdered glass in the mix.

A basic mask is better than nothing.

But a filter mask is better.

I have a couple of these and my last cost around £20 from a car paint suppliers.

b,  Nuisance;

This is the non-dangerous dust created from the use of Aluminium oxide and Silicon carbide, non-dangerous in that it does not cause Silicosis of the lungs, although it still contains powdered glass. So if you have your head in the cabinet with this dust then please wear a mask. 

The nuisance part comes in because you can't see what you are trying to achieve in your cabinet so it has to go, and there are a number of ways of achieving this.

These days a lot of the cabinets come with the extractor bolted on the back and all come with the provision to plug in some kind of vacuum system, these rely on your ingenuity of what to plug in and sometimes the wrong decision is made so getting it right the first time saves a lot of bother in the future.

Ready Fitted

These are the more expensive cabinets although you can buy the same cabinet with the extractor not fitted but provision is made to bolt on when you acquire the extractor.

This cabinet is approx £740 with delivery.

These are large extractors 78cm x 30cm x 32cm and weigh around 10kgs, they also take up a lot of space at the back of the cabinet so no use in a small shed and cost around £150 with delivery.

The extractor is motor driven and sucks the air from the cabinet passes it through a filter and out of the top cowling cover.

The filters can be removed for cleaning and exchange filters are available for around £40 each.

If for some reason the motors should burn out (hopefully not) then there is even a spare motor available for £70.

You can also buy floor mounted units that are designed for dust and have bags for collection and easy removal. These are around £300 with delivery

This type sits along side your cabinet for easy hose connection and start stop.

This Glastar system gets is suction from a vacuum and has a cyclonic separator to prevent the vacuum getting blocked..

This type of system is easily achieved for the DIYer and is what I have fitted to my cabinet and it works very well

The separator is fitted in line between the suction and the cabinet, this help to prevent dust getting to the vacuum, all vacuums have a variety of filters fitted to prevent dust getting in and damaging the motor, once these start blocking up then performance drops considerably.

The Internet is filled with homemade solutions to this problem and most work by using cyclonic separation either using or in a sealed air tight drum, I have linked a number of home made ideas from Pinterest.
Pinterest on DIY extraction

Most of these designs were developed for woodworking dust and chip removal but work equally as well for cabinet dust with many ingenious designs.

I have gone a similar route but have bought the cyclonic unit.

These are made of plastic and are designed to bolt onto an airtight drum and the vacuum is plugged into the top. The side inlet is plumbed into the cabinet and when switched on creates a cyclone in the chamber and sucks everything into the drum without it ever reaching the vacuum filters.

There are a lot of different manufactures out there and the first (i believe) was called the Dust Mite

but they all work on the same principle, I went for the Omni as it was the only British made one I could find.
This is mine, around £34 for the cyclone and around £15 for the drum, a used industrial vacuum was £50 plus a Dyson hose at £9 just under £110.

The connections in ready built cabinets may be a hole in the side or back but as mine is home made and large I have fitted two outlets and have used 1 1/2" plastic pipe to plumb them in.

I plumbed mine into the top corners of the cabinet as that seems to be where the bought cabinets have them positioned, maybe right maybe wrong but seems to work. I have also made deflector plates from sheet metal to prevent any direct entrance to the pipe.

This system seems to work very well and if you don't wish to go to the trouble of making one of these your self they are available for around £800.

Of course this is not the only method.

This one sucks directly into the vacuum, will do the job but the filters will get clogged very quickly.

This one uses and industrial fan but where does the dust go.

This is a home made cyclone, generally with a few inches of water in the bottom to collect the dust.

Another fancy system, not sure what the down pipes are for but looks like it goes directly into the vacuum

And last but not least another cyclone like the route I decided on.

So there are many ways of removing the dust to see what you are doing and of course so as you don't breath any in, the choice is yours.

Paul