Identifying Grills

Does anyone have an easy way to identify grills on used 19th century stamps on cover? I just bought a bunch of supposedly #94 on cover and I have a tough time finding the grills on most of these. Some just "pop", others I am really struggling with. I have tried up to a 20X magnifier. I have also tried scanning and blowing the image up. I have tried the retroreveal tool. I have even tried putting them under a microscope at 120X. My eyes are not what they used to be for fly specking and I was hoping someone had a better idea for me. I looked for this as an existing topic and I could not find anything.

http://www.jamesdire.net/grill.html

Try here, also you can use the pencil lead trick. Vigorously scribble on a piece of paper with a #2 Pencil and try to compile a small pile of lead. With your fingertip gently rub the pencil lead over the back of the stamp and it should reveal the Grill.

Stallzer,
While that link makes for great reference material. It does not help me in seeing the grills any better. Their example is a blown up image on the scanner, so maybe that is the most effective. It is just a slow process. They do note that the later issues, like the 94's I am looking into, were grilled multiple sheets at a time and the grills are points down. Those two factors can make them very faint and incomplete. So my guess is, there is no easy way for 55 year old eyes to see faint grills on 150 year old grilled covers.

Stallzer,
I don't want to remove the stamps from the covers, so the pencil idea is not an option. Great idea for loose stamps. I can usually find the grills on loose stamps. It is on cover where I need help.
Pat

You have picked the hardest thing to do with tired old eyes. What I do is find the grill marks on the four corners. I make a small mark wit a #2 pencil. I then measure the distances between. You can use a white eraser to remove the marks when finished. If you can't find enough of the grill marks then move on to the next cover.

Sorry PJS, I read right past the part where you stated they were on cover, my bad.

Turn off the lights and then shine only side light at a low, oblique angle. The shadows on one side of the grill point impression coupled with light hitting the other side will bring out each point out so that you can see and count them.

Lots of great input. The "lights out" trick did help and that link was good information to have. It was much more detailed then what I already had.
Thanks Guys,
Pat